FDA Label for Dorzolamide Hydrochloride And Timolol Maleate Ophthalmic Solution

Indications And Usage

  Dorzolamide hydrochloride and timolol maleate ophthalmic solution is indicated for the reduction of elevated intraocular pressure (IOP) in patients with open -angle glaucoma or ocular hypertension who are insufficiently responsive to bet a-blockers (failed to achieve target IOP determined after multiple measurements over time). The IOP-lowering of dorzolamide hydrochloride and timolol maleate ophthalmic solution ad ministered twice a day was slightly less than that seen with the concomitant administration of 0.5% ti molol administered twice a day and 2% dorzola mide administered three times a day [see Clinical Studies ( 14)].

Dosage And Administration

The dose is one drop of dorzolamide hydrochloride and timolol maleate ophthalmic solution in the affected eye(s) two times daily.

If more than one topical ophthalmic drug is being used, the drugs should be administered at least five minutes apart [see Drug Interactions ( 7.3)].

Dosage Forms And Strengths

Solution containing 20 mg/mL dorzolamide (22.26 mg of dorzolamide hydrochloride) and 5 mg /mL ti molol (6.83 mg ti molol maleate).

4.1 Asthma, Copd

Dorzolamide Dorzolamide hydrochloride and timolol maleate ophthalmic solution is contraindicated in patients with bronchial asthma, a histo ry of bronchial asthma, or severe chronic obstructive pulmonary disease [see Warnings and Precautions ( 5.1)] .

4.2 Sinus Bradycardia, Av Block, Cardiac Failure, Cardiogenic Shock

Dorzolamide Dorzolamide hydrochloride and timolol maleate ophthalmic solution is contraindicated in patients with sinus bradycardia, second or third degree atrioventricular block, overt cardiac failure, and cardiogenic shock [see Warnings and Precautions ( 5.2)] .

4.3 Hypersensitivity

Dorzolamide hydrochloride and timolol maleate ophthalmic solution is contraindicated in patients who are hypersensitive to any component of this product [see Warnings and Precautions ( 5.3)] .

5.1 Potentiation Of Respiratory Reactions Including Asthma

Dorzolamide hydrochloride and timolol maleate ophthalmic solution contains timolol maleate, a be ta -adrenergic blocking agent; and although administered topically, is absorbed s y stemically. Therefore, the same types of adverse reactions that are attributable to s ystemic administration of beta-adrenergic blocking agents may occur with topical administr ation. For example, severe respiratory reactions, including death due to bronchospasm in patients with asthma, and rarely death in association with cardiac failure, have been reported following s y stemic or ophthalmic ad ministration of timolol maleate [see Contraindications ( 4.1) and Patient Counseling Information ( 17.1)].

5.2 Cardiac Failure

S y mpathetic stimulation may be essential for support of the circulation in individuals with di minished m yocardial contractility, and its inhibition by beta-adrenergic receptor blockade may precipitate more severe failure.

In patients without a histo ry of cardiac failure continued depression of the m yocardium with beta- blocking agents over a period of time can, in some cases, lead to cardiac failure. At the first sign or s y mptom of cardiac failure, dorzolamide hydrochloride and timolol maleate ophthalmic solution should be discontinued [see Contraindications ( 4.2) and Patient Counseling Information ( 17.2)].

5.3 Sulfonamide Hypersensitivity

Dorzolamide hydrochloride and timolol maleate ophthalmic solution contains dorzolamide, a sulfonamide; and although administered topically, it is abso rbed s ystemically. Therefore, the same t ypes of adverse reactions that are attributable to sulfonamides may occur with topical administration of dorzolamide hydrochloride and timolol maleate ophthalmic solution. Fatalities have occurred, although rarely, due to severe reactions to sulfonamides including Steven s-Joh nson s yndrome, toxic epidermal necrol ysis, fulminant hepatic necrosis, agranulocytosis, aplastic anemia, and other blood d yscrasias. Sensitization may recur when a sulfonamide is readministered irrespective of the route of administration. If signs of seri ous reactions or hypersensitivity occur, discontinue the use of this preparation [see Contraindications ( 4.3) and Patient Counseling Information ( 17.3)].

5.4 Obstructive Pulmonary Disease

Patients with chronic obstructive pulmonary disease (e.g., chronic bronchitis, emphysema) of mild or moderate severity, bronchospastic disease, or a history of bronchospastic disease (other than bronchial asthma or a history of bronchial asthma, in which dorzolamide hydrochloride and timolol maleate ophthalmic solution is contraindicated) should, in general, not receive beta-blocking agents, including dorzolamide hydrochloride and timolol maleate ophthalmic solution [see Contraindications ( 4.1) and Patient Counseling Information ( 17.1)].

5.5 Increased Reactivity To Allergens

While taking beta-blockers, patients with a histo ry of atopy or a histo ry of severe anaphylactic reactions to a variety of allergens may be more reactive to repeated accidental, diagnostic, or therapeutic challenge with such allergens. Such patients may be unresponsive to the usual doses of epinephrine used to treat anaphylactic reactions.

5.6 Potentiation Of Muscle Weakness

Beta -adrenergic blockade has been reported to potentiate muscle weakness consistent with certain m yasthenic s y mptoms (e.g., diplopia, ptosis, and generalized weakness). Timolol has been reported rarely to increase muscle weakness in some patients with myasthenia gravis or m yasthenic s y mp toms.

5.7 Masking Of Hypoglycemic Symptoms In Patients With Diabetes Mellitus

Beta -adrenergic blocking agents should be administered with caution in patients subject to spontaneous hypogl ycemia or to diabetic patients (especially those with labile diabetes) who are receiving insulin or oral hypoglycemic agents. Beta-adrenergic receptor blocking agents may mask the signs and s y mptoms of acute hypoglyce mia.

5.8 Masking Of Thyrotoxicosis

Beta -adrenergic blocking agents may mask certain clinical signs (e.g., tach ycardia) of h y perth yroidism. Patients suspected of developing th yrotoxicosis should be managed carefully to avoid abrupt withdrawal of beta-adrene rgic blocking agents that might precipitate a thyroid storm.

5.9 Renal And Hepatic Impairment

Dorzolamide has not been studied in patients with severe renal impairment (CrCl <30 mL / min). Because dorzolamide and its metabolite are excreted predominantly by the kidney, dorzolamide hydrochloride and timolol maleate ophthalmic solution is not recommended in such patients.

Dorzolamide has not been studied in patients with hepatic impairment and should therefore be used with caution in such patients.

5.10 Impairment Of Beta-Adrenergically Mediated Reflexes During Surgery

The necessity or desirability of withdrawal of beta-adrenergic blocking agents prior to major surgery is controversial. Beta-adrenergic receptor blockade impairs the ability of the heart to respond to beta-adrenergically mediated reflex stimuli. This may augment the risk of general anesthesia in surgical procedures. Some patients receiving beta-adrenergic receptor blocking agents have experienced protracted severe hypotension during anesthesia. Difficulty in restarting and maintaining the heartbeat has also been reported. For these reasons, in patients undergoing elective surgery, some authorities recommend gradual withdrawal of beta -adrenergic receptor blocking agents.

If necessary during surgery, the effe cts of beta-adrenergic blocking agents may be reversed by sufficient doses of adrenergic agonists.

5.11 Corneal Endothelium

Carbonic anhydrase activity has been observed in both the cytoplasm and around the plasma m e m branes of the corneal endothelium. There is an increased potential for developing corneal edema in patients with low endothelial cell counts. Caution should be used when prescribing dorzolamide hydrochloride and timolol maleate ophthalmic solution to this group of patients.

5.12 Bacterial Keratitis

There have been reports of bacterial keratitis associa ted with the use of multiple-dose containers of topical ophthalmic products. These containers had been inadvertently contaminated by patients who, in m ost cases, had a concurrent corneal disease or a disruption of the ocular epithelial surface [see Patient Counseling Information ( 17.4)] .

6.1 Clinical Studies Experience

Because clinical trials are conducted under widely va rying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Dorzolamide hydrochloride and timolol maleate ophthalmic solution was evaluated in 1035 patients with elevated intraocular pressure treated for ope n-angle glaucoma or ocular hypertension for up to 15 months. Approximately 5% of all patients discontinued therapy because of adverse reactions.

The most frequently reported adverse reactions occurring in up to 30% of patients were taste perversion (bitter, sour, or unusual taste) or ocular burning and/or stinging. The following adverse reactions were reported in 5 to15% of patients: conjunctival hyperemia, blurred vision, superficial punctate keratitis or eye itching.

The following adverse reactions were reported in 1 to 5% of patients: abdominal pain, back pain, blepharitis, bronchitis, cloudy vision, conjunctival discharge, conjunctival edema, conjunctival follicles, conjunctival injection, conjunctivitis, corneal erosion, corneal staining, cortical lens opacity, cough, dizziness, d r y ness of eyes, dyspepsia, eye debris, eye discharge, eye pain, eye tearing, eyelid edema, e yelid e rythe ma, eyelid exudate/scales, eyelid pain or discomfort, foreign body sensation, glaucomatous cupping, headache, hypertension, influenza, lens nucleus coloration, lens opacity, nausea, nuclear lens opaci t y, pha r y ngitis, post-subcapsular cataract, sinusitis, upper respiratory infection, urina ry tract infection, visual field defect, vitreous detachment.

Other adverse reactions that have been reported with the individual components are listed below:

Dorzolamide 2%

Angioedema, asthenia/fatigue, bronchospasm, contact dermatitis, epistaxis, eyelid crusting, ocular discomfort, photophobia, signs and s y mptoms of ocular allergic reaction, transient myopia.

Timolol (ocular administration)

Body as a Whole: Asthenia/ fatigue; Cardiovascular: Arrh ythmia, syncope, cerebral ischemia, worsening of angina pectoris, palpitation, cardiac arrest, pulmonary edema, edema, claudication, Raynaud’s phenomenon, and cold hands and feet; Digestive: Anorexia, abdominal pain; Immunologi c: S ystemic lupus erythematosus; Nervous System/Psychiatric: Increase in signs and s y mptoms of m yasthenia gravis, somnolence, insomnia, nightmares, behavioral changes and ps ychic disturbances including confusion, hallucinations, anxiety, disorientation, ne rvousness, and memory loss; Skin: Alopecia, psoriasiform rash or exacerbation of psoriasis; Hypersensitivity: Signs and s y mptoms of s ystemic allergic reactions, including anaphylaxis, angioedema, urticaria, and localized and generalized rash; Respiratory: Bronchospasm (predominantly in patients with pr e-existing bronchospastic disease); Endocrine: Masked s y mptoms of h y pogl ycemia in diabetic patients; Special Senses: Ptosis, decreased corneal sensitivity, cystoid macular edema, visual disturbances including refractive changes and diplopia, pseudopemphigoid, and tinnitus; Urogenital: Retroperitoneal fibrosis, decreased libido, impotence, and P e y ronie’s disease; Musculoskeletal: M yalgia.

6.2 Post-Marketing Experience

The following adverse reactions have been identified during post-approval use of dorzolamide hydrochloride and timolol maleate ophthalmic solution. Because these reactions are reported voluntarily from a population of uncertain size, it is not alwa ys possible to reliably estimate their frequen cy or establish a causal relationship to drug exposure: bradycardia, cardiac failure, cerebral vascular accident, chest pain, choroidal detachment following filtration surge ry, depression, diarrhea, d ry mouth, d yspnea, heart block, hypotension, iridocyclitis, m yocardial infar ction, nasal congestion, Steven s-Johnson syndrome, toxic epidermal necrolysis, paresthesia, photophobia, respirato ry failure, skin rashes, urolithiasis, and vomiting.

Timolol (oral administration)

The following additional adverse reactions have been report ed in clinical experience with ORAL ti molol maleate or other ORAL beta-blocking agents and may be considered potential effects of ophthalmic timolol maleate: Allergic: E rythe matous rash, fever combined with aching and sore throat, laryngospasm with respira t ory distress; Body as a Whole: Extremity pain, decreased exercise tolerance, weight loss; Cardiovascular: Worsening of arterial insufficiency, vasodilatation; Digestive: Gastrointestinal pain, hepatomegaly, mesenteric arterial thrombosis, ischemic colitis; Hematologic: Nonthromboc ytopenic purpura; thrombocytopenic purpura, agranulocytosis; Endocrine: H yperglycemia, hypoglycemia; Skin: Pruritus, skin irritation, increased pigmentation, sweating; Musculoskeletal: Arthralgia; Nervous System/Psychiatric: Vertigo, local weakness, diminished concentration, reversible mental depression progressing to catatonia, an acute reversible syndrome characterized by disorientation for time and place, e motional lability, slightly clouded sensorium, and decreased performance on neurops ychometrics; Respiratory: Rales, bronchial obstruction; Urogenital: Urination difficulties.

7.1 Oral Carbonic Anhydrase Inhibitors

There is a potential for an additive effect on the known s ystemic effects of carbonic anhydrase inhibition in patients receiving an oral carbonic anhydrase inhibitor and dorzolamide hydrochloride and timolol maleate ophthalmic solution. The concomitant ad ministration of dorzolamide hydrochloride and timolol maleate ophthalmic solution and oral carbonic anhydrase inhibitors is not recommended.

7.2 High-Dose Salicylate Therapy

Although acid-base and electrolyte distu rbances were not reported in the clinical trials with dorzolamide hydrochloride ophthalmic solution, these disturbances have been reported with oral carbonic anh ydrase inhibitors and have, in some instances, resulted in drug interactions (e.g., toxicity as sociated with high-dose salicylate therapy). Therefore, the potential for such drug interactions should be considered in patients receiving dorzolamide hydrochloride and timolol maleate ophthalmic solution.

7.3 Beta-Adrenergic Blocking Agents

Patients who are receiving a beta-adrenergic blocking agent orally and dorzolamide hydrochloride and timolol maleate ophthalmic solution should be observed for potential additive effects of beta-blockade, both systemic and on intraocular pressure. The concomitant use of two topical beta-adrenergic blocking agents is not recommended.

7.4 Calcium Antagonists

Caution should be used in the coadministration of bet a-adrenergic blocking agents, such as dorzolamide hydrochloride and timolol maleate ophthalmic solution, and oral or intravenous calcium antagonists because of possible atrioventricular conduction disturbances, left ventricular failure, and hypotension. In patients with impaired cardiac fu nction, coadministration should be avoided.

7.5 Catecholamine-Depleting Drugs

Close observation of the patient is recommended when a beta-blocker is administered to patients receiving catecholamine-depleting drugs, such as reserpine, because of possible additive effects and the production of hypotension and/or marked bradycardia, which may result in vertigo, syncope, or postural h ypotension.

7.6 Digitalis And Calcium Antagonists

The concomitant use of beta-adrenergic blocking agents with digitalis and calc ium antagonists may have additive effects in prolonging atrioventricular conduction time.

7.7 Cyp2d6 Inhibitors

Potentiated systemic beta -blockade (e.g., decreased heart rate, depression) has been reported during combined treatment with CYP2D6 inhibitors (e.g., quinidine, SSRIs) and timolol.

7.8 Clonidine

Oral beta-adrenergic blocking agents may exacerbate the rebound hypertension which can follow the withdrawal of clonidine. There have been no reports of exacerbation of rebound hypertension with ophthalmic ti molol maleate.

8.1 Pregnancy

Teratogenic Effect s. Pregnancy Category C. Developmental toxicity studies with dorzolamide h ydrochloride in rabbits at oral doses of ≥2.5 mg/kg/day (37 times the recommended human ophthalmic dose) revealed malformations of the vertebral bodies. These malformations occurred at doses that caused metabolic acidosis with decreased body weight gain in dams and decreased fetal weights. No treatment-related malformations were seen at 1 mg/kg/day (15 times the recommended human ophthalmic dose).

Teratogenicity studies with timolol in mice, rats, and rabbits at oral doses up to 50 mg / kg/day (7,000 ti mes the s ystemic exposure following the maximum recommended human ophthalmic dose) de monstrated no evidence of fetal malformations. Although delayed fetal ossification was observed at t his dose in rats, there were no adverse effects on postnatal development of offspring. Doses of 1,000 mg / kg/day (142,000 times the s ystemic exposure following the maximum recommended human ophthalmic dose) were maternotoxic in mice and resulted in an incre ased number of fetal resorptions.

Increased fetal resorptions were also seen in rabbits at doses of 14,000 times the s ystemic exposure following the maximum recommended human ophthalmic dose, in this case without apparent maternotoxicity.

There are no adequate and well-controlled studies in pregnant women. Dorzolamide hydrochloride and timolol maleate ophthalmic solution should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

8.3 Nursing Mothers

It is not known whether dorzolamide is excreted in human milk. Timolol maleate has been detected in human milk following oral and ophthalmic drug administration. Because of the potential for serious adverse reactions from dorzolamide hydrochloride and timolol maleate ophthalmic solution in nursing infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

8.4 Pediatric Use

The safety and effectiveness of dorzolamide hydrochloride ophthalmic solution and timolol maleate ophthalmic solution have been established when administered individually in pediatric patients aged 2 y ears and older. Use of these drug products in these children is supported by evidence from adequate and well-controlled studies in children and adults. Safety and efficacy in pediatric patients below the age of 2 years have not been established.

8.5 Geriatric Use

No overall differences in safety or effectiveness have been observed between elderly and younger patients.

10 Overdosage

S y mptoms consistent with s ystemic administration of beta-blockers or carbonic anhydrase inhibito rs may occur, including electrolyte imbalance, development of an acidotic state, dizziness, headache, shortness of breath, brad ycardia, bronchospasm, cardiac arrest and possible central nervous s ystem effects. Serum electrolyte levels (particularly potassium) and blood pH levels should be monitored. [See Adverse Reactions ( 6).]

A study of patients with renal failure showed that timolol did not dialyze readily.

11 Description

Dorzolamide hydrochloride and timolol maleate ophthalmic solution, USP is the combination of a topical carbonic anhydrase inhibitor and a topical beta -adrenergic receptor blocking agent.

Dorzolamide hydrochloride is described chemically as: (4 S-tran s)-4 -(ethylamino )-5,6-di h yd ro-6- meth yl -4 H-thieno[2,3- b]thiopyran -2 -sulfonamide 7,7-dioxide mo noh ydrochloride. Dorzolamide h ydrochloride is optically active. The specific rotation is:

[α]        25°C    (C=1, water) = ~ -17°.

            40 5nm

Its molecular formula is C ₁₀H ₁₆N ₂ O ₄S ₃•HCl and its structural formula is:

dorzolamide structure - dorzotimo dorzolamidestrc

Dorzolamide h ydrochloride has a molecular weight of 360.91. It is a white to of f-white, crystalline powder, which is soluble in water and slightly soluble in methanol and ethanol.

T i molol maleate is described chemically as: (-)-1- ( tert-butylamino )-3 -[(4- morpholino-1,2,5-thiadiazol-3 - yl)o x y]-2 -propanol maleate (1:1) (salt). Timolol maleate possesses an as y mmetric carbon atom in its structure and is provided as the levo-isomer. The optical rotation of timolol maleate is:

[α]        25 ᵒC   in 1N HCl (C = 5) = -12. 2ᵒ (-11.7ᵒ to -12.5ᵒ).

            405 nm

Its molecular formula is C _{1 3}H ₂₄N ₄ O ₃S•C ₄H ₄ O ₄ and its structural formula is:

T i molol maleate has a molecular weight of 432.50. It is a white, odorless, cr ystalline powder which is soluble in water, methanol, and alcohol. Timolol maleate is stable at room temperature.

Dorzolamide hydrochloride and timolol maleate ophthalmic solution, USP is supplied as a sterile, isotonic, buffered, clear, colorless to nearly colorless and slightly viscous solution. The pH of the solution is approximately 5.65, and the osmolarity is 242 to 323 mOsM. Each mL of dorzolamide hydrochloride and timolol maleate ophthalmic solution, USP contains 20 mg dorzolamide (22.26 mg of dorzolamide hydrochloride USP) and 5 mg timolol (6.83 mg timolol maleate USP). Inactive ingredients are Mannitol, Hydroxyethyl cellulose, Sodium hydroxide, Tri Sodium citrate Dihydrate, and water for injection. Benzalkonium chloride 0.0075% is added as a preservative.

12.1 Mechanism Of Action

Dorzolamide hydrochloride and timolol maleate ophthalmic solution is comprised of two components: dorzolamide hydrochloride and timolol maleate. Each of these two components decreases elevated intraocular pressure, whether or not associated with glaucoma, by reducing aqueous humor secretion. Elevated intraocular pressure is a major risk factor in the pathogenesis of optic nerve damage and glaucomatous visual field loss. The higher the level of intraocular pressure, the greater the likelihood of glaucomatous field loss and optic nerve damage.

Dorzolamide hydrochloride is an inhibitor of human carbonic anhydrase II. Inhibition of carbonic an h ydrase in the ciliary processes of the eye decreases aqueous humor secretion, presumably by slowing the formation of bicarbonate ions with subsequent reduction in sodium and fluid transport. Timolol maleate is a beta1 and bet a2 (non-selective) adrenergic receptor blocking agent that does not have significant intrinsic s y mpathomimetic, direct m yocardial depressant, or local anesthetic (membrane- stabilizing) activity. The combined effect of these two agents administered as dorzolamide hydrochloride and timolol maleate ophthalmic solution twice daily results in additional intraocular pressure reduction compared to either component administered alone, but the reduction is not as much as when dorzolamide administered three times daily and timolol twice daily are ad ministered concomitantly. [See Clinical Studies ( 14).]

12.3 Pharmacokinetics

Dorzolamide Hydrochloride

W hen topically applied, dorzolamide reaches the s y stemic circulation. To assess the potential for s ystemic carbonic anhydrase inhibition following topical administration, drug and metabolite concentrations in RBCs and plasma and carbonic anhydrase inhibition in RBCs were measured. Dorzolamide accumulates in RBCs during chronic dosing as a result of binding to CA-II. The parent drug forms a single N-desethyl metabolite, which inhibits CA-II less potently than the parent drug but also inhibits CA-I. The metabolite also accumulates in RBCs where it binds primarily to C A-I. Plasma concentrations of dorzolamide and metabolite are generally below the assay limit of quantitation (15nM). Dorzolamide binds moderately to plasma proteins (approximately 33%).

Dorzolamide is primarily excreted unchanged in the urine; the metabolite also is excreted in urine. After dosing is stopped, dorzolamide washes out of RBCs nonlinearly, resulting in a rapid decline of drug concentration initially, followed by a slower elimination phase with a hal f-life of about four months.

To simulate the systemic exposure after long-term topical ocular administration, dorzolamide was given orally to eight healthy subjects for up to 20 weeks. The oral dose of 2 mg twice daily closely approximates the amount of drug delivered by topical ocular administration of dorzolamide 2% three ti mes daily. Steady state was reached within 8 wee ks. The inhibition of CA-II and total carbonic anh ydrase activities was below the degree of inhibition anticipated to be necessa ry for a pharmacological effect on renal function and respiration in healthy individuals.

Timolol Maleate

In a study of plasma d rug concentrations in six subjects, the systemic exposure to timolol was determined following twice daily topical administration of timolol maleate ophthalmic solution 0.5%. The mean peak plasma concentration following morning dosing was 0.46 ng/mL.

13.1 Carcinogenesis & Mutagenesis & Impairment Of Fertility

In a two - y ear study of dorzolamide hydrochloride administered orally to male and female Spragu e- Dawley rats, urinary bladder papillomas were seen in male rats in the highest dosa ge group of 20 mg / kg/day (250 times the recommended human ophthalmic dose). Papillomas were not seen in rats given oral doses equivalent to approximately 12 times the recommended human ophthalmic dose. No treatment-related tumors were seen in a 21- month stu dy in female and male mice given oral doses up to 75 mg / kg/day (~900 times the recommended human ophthalmic dose).

The increased incidence of urina ry bladder papillomas seen in the high -dose male rats is a clas s- effect of carbonic anhydrase inhibitors in rats. Rats are particularly prone to developing papillomas in response to foreign bodies, compounds causing cr ystalluria, and diverse sodium salts.

No changes in bladder urothelium were seen in dogs given oral dorzolamide hydrochloride for one y ear at 2 mg/kg/day (25 times the recommended human ophthalmic dose) or monke ys dosed topically to the eye at 0.4 mg/kg/day (~5 times the recommended human ophthalmic dose) for one year.

In a two - y ear study of timolol maleate administered orally to rats, there was a statistically significant increase in the incidence of adrenal pheochromoc ytomas in male rats administered 300 mg / kg/day (approximately 42,000 times the systemic exposure following the maximum recommended human ophthalmic dose). Similar differences were not observed in rats administered oral doses equivalent to approximately 14,000 times the maximum recommended human ophthalmic dose.

In a lifetime oral study of timolol maleate in mice, there were statistically significant increases in the incidence of benign and malignant pulmonary tumors, benign uterine polyps and mammary adenocarcinomas in female mice at 500 mg/kg/day, (approximately 71,000 times the systemic exposure following the maximum recommended human ophthalmic dose), but not at 5 or 50 mg / kg/day (approximately 700 or 7,000, respectively, times the systemic exposure following the maximum recommended human ophthalmic dose). In a subsequent study in female mice, in which pos t- mortem examinations were limited to the uterus and the lungs, a statistically significant increase in the incidence of pulmonary tumors was again observed at 500 mg/kg/d a y.

The increased occurrence of mammary adenocarcinomas was associated with elevations in serum prolactin which occurred in female mice administered oral timolol at 500 mg / kg/day, but not at doses of 5 or 50 mg/kg/day. An increased incidence of mammary adenocarcinomas in rodents has been associated with administration of several other therapeutic agents that elevate serum prolactin, but no correlation between serum prolactin levels and mammary tumors has been established in humans. Furthermore, in adult human female subjects who received oral dosages of up to 60 mg of timolol maleate (the maximum recommended human oral dosage), there were no clinically meaningful chang es in serum prolactin.

The following tests for mutagenic potential were negative for dorzolamide: (1) in vivo ( mouse) c ytogenetic assay; (2) in vitro chromosomal aberration assay; (3) alkaline elution assay; (4) V-79 assay; and (5) Ames test.

T i molol maleate was devoid of mutagenic potential when tested in vivo (mouse) in the micronucleus test and cytogenetic assay (doses up to 800 mg/kg) and in vitro in a neoplastic cell transformation assay (up to 100 mcg/mL). In Ames tests the highest concentrations of ti molol e mpl oyed, 5,000 or 10,000 mcg/plate, were associated with statistically significant elevations of revertants observed with tester strain TA100 (in seven replicate assays), but not in the remaining three strains. In the assa ys with tester strain TA100, no consistent dose response relationship was observed, and the ratio of test to control revertants did not reach 2. A ratio of 2 is usually considered the criterion for a positive Ames test.

Reproduction and fertility studies in rats with either timolol maleate or dorzolamide hydrochloride de monstrated no adverse effect on male or female fertility at doses up to approximately 100 times the s ystemic exposure following the maximum recommended human ophthalmic dose.

14 Clinical Studies

Clinical studies of 3 to 15 months duration were conducted to compare the IOP -lowering effect over the course of the day of dorzolamide hydrochloride and timolol maleate ophthalmic solution twice daily (dosed morning and bedtime) to individually and concomitantly administered 0.5% timolol twice daily and 2% dorzola mide twice and three times daily. The IOP-lowering effect of dorzolamide hydrochloride and timolol maleate ophthalmic solution twice daily was greater (1 to 3 mmHg) than that of monotherapy with either 2% dorzolamide three times daily or 0.5% timolol twice daily. The IOP-lowering effect of dorzolamide hydrochloride and timolol maleate ophthalmic solution twice daily was approximately 1 mmHg less than that of concomitant therapy with 2% dorzolamide three ti mes daily and 0.5% timolol twice daily.

Open-label extensions of two studies were conducted for up to 12 months. During this period, the IOP-lowering effect of dorzolamide hydrochloride and timolol maleate ophthalmic solution t wice daily was consistent during the 12 month follow-up period.

16 How Supplied/Storage And Handling

Dorzolamide hydrochloride and timolol maleate ophthalmic solution, USP is a clear, colorless to nearly colorless, slightly viscous solution.

Dorzolamide hydrochloride and timolol maleate ophthalmic solution, USP is supplied in an LDPE white opaque cylindrical shape, screw type neck dispenser bottle closed with a LDPE white opaque cone shaped open nozzle and an HDPE blue color cone shaped TSTR-TEAR off cap as follows.

NDC 42571-147-26, 10 mL in a 10 mL capacity bottle.

Storage

Store Dorzolamide Hydrochloride and Timolol Maleate Ophthalmic Solution, USP at 20° to 25°C (68° to 77°F) [see USP Controlled Room Temperature]. Protect from light.

17 Patient Counseling Information

See FDA-Approved Patient Labeling (Patient Information).

17.1 Potential For Exacerbation Of Asthma And Copd

Dorzolamide hydrochloride and timolol maleate ophthalmic solution may cause severe worsening of asthma and COPD s y mptoms including death due to bronchospasm. Advise patients with bronchial asthma, a history of bronchial asthma, or severe chronic obstructive pulmonary disease not to take this product. [see Contraindications ( 4.1)].

17.2 Potential Of Cardiovascular Effects

Dorzolamide hydrochloride and timolol maleate ophthalmic solution may cause worsening of cardiac s y mptoms. Advise patients with sinus bradycardia, second or third degree atrioventricular block, or cardiac failure not to take this product. [see Contraindications ( 4.2)].

17.3 Sulfonamide Reactions

Dorzolamide hydrochloride and timolol maleate ophthalmic solution contains dorzolamide (which is a sul fona mide) and, although administered topically, is absorbed systemically. Therefore the same types of adverse reactions that are attributable to sulfonamides may occur with topical administration, including severe skin reactions. Advise patients that if se rious or unusual reactions or signs of hypersensitivity occur, they should discontinue the use of the product and seek their physician's advice. [see Warnings and Precautions ( 5.3)].

17.4 Handling Ophthalmic Solutions

Instruct patients that ocular solutions, if handled improperly or if the tip of the dispensing container contacts the eye or surrounding structures, can become contaminated by common bacteria known to cause ocular infections. Serious damage to the eye and subsequent loss of vision may result from using contaminated solutions. [see Warnings and Precautions ( 5.12)].

17.5 Intercurrent Ocular Conditions

Advise patients that if they have ocular surge ry or develop an intercurrent ocular condition (e.g., trauma or infection ), they should immediately seek their ph ysician's advice concerning the continued use of the present multidose container.

17.6 Concomitant Topical Ocular Therapy

If more than one topical ophthalmic drug is being used, the drugs should be ad ministered at least five minutes apart.

17.7 Contact Lens Use

Advise patients that dorzolamide hydrochloride and timolol maleate ophthalmic solution contains benzalkonium chloride which may be absorbed by soft contact lenses. Contact lenses should be removed prior to administration of the solution. Lenses may be reinserted 15 minutes following administration of dorzolamide hydrochloride and timolol maleate ophthalmic solution.   

Manufactured by:

Micro Labs Limited

Bangalore – 560 099, India.

Manufactured for:

Micro Labs USA Inc.

Basking Ridge, NJ 07920

Patient Information

Dorzolamide Hydrochloride and Timolol Maleate Ophthalmic Solution

(dor-ZOE-la-mide HYE-droe-KLOR-ide/TIM-oh-lol MAL-ee-ate)

Read this information before you start using dorzolamide hydrochloride and timolol maleate ophthalmic solution and each time you refill your prescription. This is in case any information has changed. This leaflet provides a summary of certain information about dorzolamide hydrochloride and timolol maleate ophthalmic solution. Your doctor or pharmacist can give you more complete information about dorzolamide hydrochloride and timolol maleate ophthalmic solution. This leaflet does not take the place of careful discussions with your doctor.  You and your doctor should discuss dorzolamide hydrochloride and timolol maleate ophthalmic solution when you start using your medicine at regular checkups. Only your doctor can prescribe dorzolamide hydrochloride and timolol maleate ophthalmic solution or you.

What is dorzolamide hydrochloride and timolol maleate ophthalmic solution?

Dorzolamide hydrochloride and timolol maleate ophthalmic solution is an eyedrop. It contains dorzolamide hydrochloride, which is an ophthalmic carbonic anhydrase inhibiting drug. It also contains timolol maleate, which is a beta-blocking drug. Both drugs work to lower pressure in the eye, but in different ways.

Dorzolamide hydrochloride and timolol maleate ophthalmic solution is a medicine for lowering pressure in the eye in people with open-angle glaucoma or ocular hypertension. It is used when a beta-blocker eyedrop alone is not adequate to control eye pressure.

What should I know about high pressure in the eye?

People with open-angle glaucoma or ocular hypertension have pressures in one or both of their eye(s) that are too high for them.

High pressure in the eye may damage the optic nerve. This may lead to loss of vision and possible blindness. There generally are few symptoms that you can feel to tell you whether you have high pressure within your eye. Your doctor needs to examine your eyes to determine this. If you have high pressure in your eye, you will need your pressure checked and your eyes examined regularly.

Who should not use dorzolamide hydrochloride and timolol maleate ophthalmic solution?

Do not use dorzolamide hydrochloride and timolol maleate ophthalmic solution if you have:

• or have ever had asthma,
• severe lung problems (such as chronic obstructive pulmonary disease),
• heart problems, including slow or irregular heartbeat or heart failure,
• allergies to any of its ingredients. See the list at the end of the leaflet.



If you are not sure whether you should use dorzolamide hydrochloride and timolol maleate ophthalmic solution, contact your doctor or pharmacist.

What should I tell my doctor before and during treatment withdorzolamide hydrochloride and timolol maleate ophthalmic solution?

Tell your doctor:

• if you are pregnant or plan to become pregnant,
• if you are breast-feeing or intend to breast-feed,
• about any medical problems you have now or had in the past, especially heart problems or breathing problems including asthma,
• if you now have or had in the past kidney or liver problems,
• if you have diabetes, thyroid disease or muscle weakness,
• about all medicines that you are taking or plan to take, including those you can get without a prescription,
• about any allergies including allergies to any medications, especially sulfa drugs,
• if you develop an eye infection, develop a red or swollen eye or eyelid, receive an eye injury, have eye surgery, or develop new or worsening eye symptoms,
• if you plan on having any type of surgery.




How should I use dorzolamide hydrochloride and timolol maleate ophthalmic solution?




Dorzolamide hydrochloride and timolol maleate ophthalmic solution is an eyedrop. The usual dose is one drop in the morning and one drop in the evening. Your doctor will tell you if just one or both eyes are to be treated.




If you are using dorzolamide hydrochloride and timolol maleate ophthalmic solution with another eyedrop, the eyedrops should be used at least 5 minutes apart. It is very important to use your medication exactly as directed by your doctor. If you stop using your medicine, contact your doctor immediately.




Dorzolamide hydrochloride and timolol maleate ophthalmic solution contains a preservative called benzalkonium chloride. This preservative may be absorbed by soft contact lenses. Contact lenses should be removed before using dorzolamide hydrochloride and timolol maleate ophthalmic solution. The lenses can be placed back into your eyes 15 minutes after using the eyedrops.




Do not allow the tip of the bottle to touch the eye or areas around the eye. The bottle may become contaminated with bacteria. This can cause eye infections leading to serious damage to the eye, even loss of vision. Keep the tip of the bottle away from contact with any surface to avoid contamination.




INSTRUCTION FOR USE




Please follow these instructions carefully when using dorzolamide hydrochloride and timolol maleate ophthalmic solution. Use dorzolamide hydrochloride and timolol maleate ophthalmic solution as prescribed by your doctor.




1. If you use other topically applied ophthalmic medications, they should be administered at least 5 minutes before or after dorzolamide hydrochloride and timolol maleate ophthalmic solution.




2. Wash hands before each use.




3. Before using the medication for the first time, be sure the tamper evident ring between the bottle and the cap is unbroken (See Figure A).

4. Before opening the bottle for the first time, tear off the tamper evident ring to break the seal (See Figure B).

5. To open the bottle, unscrew the cap by turning it in the counterclockwise direction (See Figure C).

6. Tilt your head back and pull your lower eyelid down slightly to form a pocket between your eyelid and your eye. (See Figure D).

7. Invert the bottle, and press lightly with the thumb or index finger until a single drop is dispensed into the eye as directed by your doctor (See Figure E).




DO NOT TOUCH YOUR EYE OR EYELID WITH THE DROPPER TIP.




OPHTHALMIC MEDICATIONS, IF HANDLED IMPROPERLY, CAN BECOME CONTAMINATED BY COMMON BACTERIA KNOWN TO CAUSE EYE INFECTIONS. SERIOUS DAMAGE TO THE EYE AND SUBSEQUENT LOSS OF VISION MAY RESULT FROM USING CONTAMINATED OPHTHALMIC MEDICATIONS. IF YOU THINK YOUR MEDICATION MAY BE CONTAMINATED, OR IF YOU DEVELOP AN EYE INFECTION, CONTACT YOUR DOCTOR IMMEDIATELY CONCERNING CONTINUED USE OF THIS BOTTLE.




8. Repeat steps 6 & 7 with the other eye if instructed to do so by your doctor




9. The dispenser tip is designed to provide a single drop; therefore, do NOT enlarge the hole of the dispenser tip.




10.  After you have used all doses, there will be some dorzolamide hydrochloride and timolol maleate ophthalmic solution left in the bottle. You should not be concerned since an extra amount of dorzolamide hydrochloride and timolol maleate ophthalmic solution has been added and you will get the full amount of dorzolamide hydrochloride and timolol maleate ophthalmic solution that your doctor prescribed. Do not attempt to remove the excess medicine from the bottle.

Can I use ddorzolamide hydrochloride and timolol maleate ophthalmic solution with other medicines?




Tell your doctor or pharmacist about all drugs that you are using or plan to use. This includes other eye drops and drugs obtained without a prescription. This is particularly important if you are taking medicine to lower blood pressure or to treat heart disease, medicines to treat diabetes, or if you are taking large doses of aspirin.




Ask your doctor’s advice about taking dorzolamide hydrochloride and timolol maleate ophthalmic solutionif you are also using:

• oral carbonic anhydrase inhibitors (for example, acetazolamide, Diamox ^®)
• oral beta-blockers (for example, propranolol, Inderal ^®)
• calcium antagonists (for example, nifedipine, Procardia ^®)
• catecholamine-depleting drugs (for example, reserpine)
• digitalis in combination with calcium antagonists (for example, Lanoxin ^® with Procardia ^®)
• quinidine (for example, Cardioquin ^®)
• clonidine (for example, Catapres ^®)
• injectable epinephrine (for example, EpiPen ^®)
• certain antidepressants (for example, Prozac ^®)



Your doctor or pharmacist can tell you if any of the drugs you are using are in the above list.

What are the possible side effects of dorzolamide hydrochloride and timolol maleate ophthalmic solution?




Any medicine may have unintended or undesirable effects. These are called side effects. Side effects may not occur, but if they do occur, you may need medical attention. The most common side effects you may experience are:



• eye symptoms such as burning and stinging, redness of the eye(s), blurred vision, tearing or itching.
• a bitter, sour or unusual taste after putting in your eyedrops.



Other side effects may occur rarely, and some of these may be serious. Tell your doctor right away if your experience:

• shortness of breath
• visual changes
• an irregular heartbeat and/or a slowing of your heart rate
• severe skin reactions



The above list is NOT a complete list of side effects reported with dorzolamide hydrochloride and timolol maleate ophthalmic solution. Your doctor can discuss with you a more complete list of side effects. Please tell your doctor [or pharmacist] promptly about any of these or any other unusual symptom.




What should I do in case of an overdose?




If you swallow the contents of the bottle, contact your doctor immediately. Among other effects, you may feel light-headed, have difficulty breathing, or feel your heart rate has slowed.




How should I storedorzolamide hydrochloride and timolol maleate ophthalmic solution?




Keep your medicine in a safe place where children cannot reach it. Store dorzolamide hydrochloride and timolol maleate ophthalmic solution at room temperature 20° to 25°C (68° to 77°F). Protect the bottle from light. Do not use your medicine after the expiration date on the bottle.




What else should I know about ddorzolamide hydrochloride and timolol maleate ophthalmic solution?




Do not use dorzolamide hydrochloride and timolol maleate ophthalmic solution for a condition for which it was not prescribed. Do not give dorzolamide hydrochloride and timolol maleate ophthalmic solution to other people, even if they have the same condition you have. It may harm them.




Inactive ingredients:




The inactive ingredients of dorzolamide hydrochloride and timolol maleate ophthalmic solution are Mannitol, Hydroxyethyl cellulose, Sodium hydroxide, Tri Sodium citrate Dihydrate, water for injection, and benzalkonium chloride is added as a preservative.




Manufactured by:

Micro Labs Limited

Bangalore – 560099, India.




Manufactured for:

Micro Labs USA Inc.

Basking Ridge, NJ 07920

Package Label.Principal Display Panel

NDC 42571-147-26        Rx Only
Dorzolamide HCl/
Timolol Maleate
Ophthalmic Solution
22.3 mg/6.8 mg per mL*
FOR USE IN THE EYES
ONLY 
10 mL

NDC 42571-147-26

Dorzolamide HCl/
Timolol Maleate
Ophthalmic Solution
22.3 mg/
6.8 mg per mL*
FOR USE IN THE EYES
ONLY
Rx Only
10 mL