Bromocriptine mesylate tablets are indicated in the treatment of the signs and symptoms of idiopathic or postencephalitic Parkinson's disease. As adjunctive treatment to levodopa (alone or with a peripheral decarboxylase inhibitor), bromocriptine mesylate tablets therapy may provide additional therapeutic benefits in those patients who are currently maintained on optimal dosages of levodopa, those who are beginning to deteriorate (develop tolerance) to levodopa therapy, and those who are experiencing "end of dose failure" on levodopa therapy. Bromocriptine mesylate tablets therapy may permit a reduction of the maintenance dose of levodopa and, thus may ameliorate the occurrence and/or severity of adverse reactions associated with long-term levodopa therapy such as abnormal involuntary movements (e.g., dyskinesias) and the marked swings in motor function ("on-off" phenomenon). Continued efficacy of bromocriptine mesylate tablets therapy during treatment of more than 2 years has not been established.
Data are insufficient to evaluate potential benefit from treating newly diagnosed Parkinson's disease with bromocriptine mesylate tablets. Studies have shown, however, significantly more adverse reactions (notably nausea, hallucinations, confusion and hypotension) in bromocriptine mesylate-treated patients than in levodopa/carbidopa-treated patients. Patients unresponsive to levodopa are poor candidates for bromocriptine mesylate tablets therapy.
Safety during long-term use for more than 2 years at the doses required for parkinsonism has not been established.
As with any chronic therapy, periodic evaluation of hepatic, hematopoietic, cardiovascular, and renal function is recommended. Symptomatic hypotension can occur and, therefore, caution should be exercised when treating patients receiving antihypertensive drugs.
High doses of bromocriptine mesylate may be associated with confusion and mental disturbances. Since parkinsonian patients may manifest mild degrees of dementia, caution should be used when treating such patients.
Bromocriptine mesylate administered alone or concomitantly with levodopa may cause hallucinations (visual or auditory). Hallucinations usually resolve with dosage reduction; occasionally, discontinuation of bromocriptine mesylate is required. Rarely, after high doses, hallucinations have persisted for several weeks following discontinuation of bromocriptine mesylate.
As with levodopa, caution should be exercised when administering bromocriptine mesylate to patients with a history of myocardial infarction who have a residual atrial, nodal, or ventricular arrhythmia.
Retroperitoneal fibrosis has been reported in a few patients receiving long-term therapy (2 to 10 years) with bromocriptine mesylate in doses ranging from 30-140 mg daily.
Epidemiological studies have shown that patients with Parkinson’s disease have a higher risk (2-approximately 6-fold higher) of developing melanoma than the general population. Whether the increased risk observed was due to Parkinson’s disease or other factors, such as drugs used to treat Parkinson’s disease, is unclear. For the reasons stated above, patients and providers are advised to monitor for melanomas frequently and on a regular basis when using bromocriptine mesylate for any indication. Ideally, periodic skin examinations should be performed by appropriately qualified individuals (e.g., dermatologists).
Discontinuation of bromocriptine mesylate should be undertaken gradually whenever possible, even if the patient is to remain on levodopa. A symptom complex resembling the neuroleptic malignant syndrome (characterized by elevated temperature, muscular rigidity, altered consciousness, and autonomic instability), with no other obvious etiology, has been reported in association with rapid dose reduction, withdrawal of, or changes in antiparkinsonian therapy.
Symptoms including apathy, anxiety, depression, fatigue, insomnia, sweating, and pain have been reported during taper or after discontinuation of dopamine agonists, including bromocriptine mesylate. These symptoms generally do not respond to levodopa. Prior to discontinuation of bromocriptine mesylate, patients should be informed about potential withdrawal symptoms, and closely monitored during and after discontinuation of bromocriptine mesylate. In case of severe withdrawal symptoms, re-administration of a dopamine agonist at the lowest effective dose may be considered.
In clinical trials in which bromocriptine mesylate was administered with concomitant reduction in the dose of levodopa/carbidopa, the most common newly appearing adverse reactions were: nausea, abnormal involuntary movements, hallucinations, confusion, “on-off’’ phenomenon, dizziness, drowsiness, faintness/fainting, vomiting, asthenia, abdominal discomfort, visual disturbance, ataxia, insomnia, depression, hypotension, shortness of breath, constipation, and vertigo.
Less common adverse reactions which may be encountered include: anorexia, anxiety, blepharospasm, dry mouth, dysphagia, edema of the feet and ankles, erythromelalgia, epileptiform seizure, fatigue, headache, lethargy, mottling of skin, nasal stuffiness, nervousness, nightmares, paresthesia, skin rash, urinary frequency, urinary incontinence, urinary retention, and rarely, signs and symptoms of ergotism such as tingling of fingers, cold feet, numbness, muscle cramps of feet and legs or exacerbation of Raynaud’s syndrome.
Abnormalities in laboratory tests may include elevations in blood urea nitrogen, SGOT, SGPT, GGPT, CPK, alkaline phosphatase and uric acid, which are usually transient and not of clinical significance.
The basic principle of bromocriptine mesylate tablets therapy is to initiate treatment at a low dosage and, on an individual basis, increase the daily dosage slowly until a maximum therapeutic response is achieved. The dosage of levodopa during this introductory period should be maintained, if possible. The initial dose of bromocriptine mesylate is half of a 2.5 mg tablet twice daily with meals. Assessments are advised at 2-week intervals during dosage titration to ensure that the lowest dosage producing an optimal therapeutic response is not exceeded. If necessary, the dosage may be increased every 14 to 28 days by 2.5 mg/day with meals. Should it be advisable to reduce the dosage of levodopa because of adverse reactions, the daily dosage of bromocriptine mesylate, if increased, should be accomplished gradually in small (2.5 mg) increments.
The safety of bromocriptine mesylate has not been demonstrated in dosages exceeding 100 mg/day.