Antimicrobial Activity
Doxycycline has been shown to be active against most isolates of the following microorganisms, both in vitro and in clinical infections (see INDICATIONS AND USAGE).
Gram-Negative Bacteria
Acinetobacter species
Bartonella bacilliformis
Brucella species
Enterobacter aerogenes
Escherichia coli
Francisella tularensis
Haemophilus ducreyi
Haemophilus influenzae
Klebsiella granulomatis
Klebsiella species
Neisseria gonorrhoeae
Shigella species
Vibrio cholerae
Vibrio fetus
Yersinia pestis
Gram-Positive Bacteria
Bacillus anthracis
Listeria monocytogenes
Streptococcus pneumoniae
Anaerobes
Clostridium species
Fusobacterium fusiforme
Propionibacterium acnes
Other Bacteria
Nocardiae and other aerobic Actinomyces species
Borrelia recurrentis
Chlamydophila psittaci
Chlamydia trachomatis
Mycoplasma pneumoniae
Rickettsiae
Treponema pallidum
Treponema pallidum subspecies pertenue
Ureaplasma urealyticum
Parasites
Balantidium coli
Entamoeba species
Plasmodium falciparum*
*Doxycycline has been found to be active against the asexual erythrocytic forms of Plasmodium falciparum, but not against the gametocytes of P. falciparum. The precise mechanism of action of the drug is not known.
Susceptibility Testing Methods
When available, the clinical microbiology laboratory should provide cumulative reports of in vitro susceptibility test results for antimicrobial drugs used in local hospitals and practice areas as periodic reports that describe the susceptibility profile of nosocomial and community-acquired pathogens. These reports should aid the physician in selecting the most effective antimicrobial.
Dilution Techniques:
Quantitative methods are used to determine antimicrobial minimum inhibitory concentrations (MICs). These MICs provide estimates of the susceptibility of bacteria to antimicrobial compounds. The MICs should be determined using a standardized test method (broth and/or agar).1,2,4,6,7 The MIC values should be interpreted according to criteria provided in Table 1.
Diffusion Techniques
Quantitative methods that require measurement of zone diameters can also provide reproducible estimates of the susceptibility of bacteria to antimicrobial compounds. The zone size should be determined using a standard test method.1,3,4 This procedure uses paper disks impregnated with 30 mcg doxycycline to test the susceptibility of bacteria to doxycycline. The disk diffusion interpretive criteria are provided in Table 1.
Anaerobic Techniques
For anaerobic bacteria, the susceptibility to doxycycline can be determined by a standardized test method.1, 5 The MIC values obtained should be interpreted according to the criteria provided in Table 1.
Table 1: Susceptibility Test Interpretive Criteria for Doxycycline and Tetracycline |
| Bacteria* | Minimal Inhibitory
Concentration (mcg/mL) | Zone Diameter (mm) | Agar Dilution (mcg/mL) |
| S | I | R | S | I | R | S | I | R |
| Acinetobacter spp. | | | | | | | | | |
| Doxycycline | ≤4 | 8 | ≥16 | ≥13 | 10 to 12 | ≤9 | - | - | - |
| Tetracycline | ≤4 | 8 | ≥16 | ≥15 | 12 to 14 | ≤11 | - | - | - |
| Anaerobes | | | | | | | | | |
| Tetracycline | - | - | - | - | - | - | ≤4 | 8 | ≥16 |
| Bacillus anthracis† | | | | | | | | | |
| Doxycycline | ≤1 | - | - | - | - | - | - | - | - |
| Tetracycline | ≤1 | - | - | - | - | - | - | - | - |
| Brucella species† | | | | | | | | | |
| Doxycycline | ≤1 | - | - | - | - | - | - | - | - |
| Tetracycline | ≤1 | - | - | - | - | - | - | - | - |
| Enterobacteriaceae | | | | | | | | | |
| Doxycycline | ≤4 | 8 | ≥16 | ≥14 | 11 to 13 | ≤10 | - | - | - |
| Tetracycline | ≤4 | 8 | ≥16 | ≥15 | 12 to 14 | ≤11 | - | - | - |
| Franciscella tularensis† | | | | | | | | | |
| Doxycycline | ≤4 | - | - | - | - | - | - | - | - |
| Tetracycline | ≤4 | - | - | - | - | - | - | - | - |
| Haemophilus influenzae | | | | | | | | | |
| Tetracycline | ≤2 | 4 | ≥8 | ≥29 | 26 to 28 | ≤25 | - | - | - |
| Mycoplasma pneumoniae† | | | | | | | | | |
| Tetracycline | - | - | - | - | - | - | ≤2 | - | - |
| Neisseria gonorrhoeae‡ | | | | | | | | | |
| Tetracycline | - | - | - | ≥38 | 31 to 37 | ≤30 | ≤0.25 | 0.5 to 1 | ≥2 |
| Norcardiae and other aerobic Actinomyces species | | | | | | | | | |
| Doxycycline | ≤1 | 2 to 4 | ≥8 | - | - | - | - | - | - |
| Streptococcus pneumoniae | | | | | | | | | |
| Doxycycline | ≤ 0.25 | 0.5 | > 1 | > 28 | 25 to 27 | < 24 | - | - | - |
| Tetracycline | <1 | 2 | > 4 | > 28 | 25 to 27 | < 24 | - | - | - |
| Vibrio cholerae | | | | | | | | | |
| Doxycycline | ≤4 | 8 | ≥16 | - | - | - | - | - | - |
| Tetracycline | ≤4 | 8 | ≥16 | - | - | - | - | - | - |
| Yersinia pestis | | | | | | | | | |
| Doxycycline | ≤4 | 8 | ≥16 | - | - | - | - | - | - |
| Tetracycline | ≤4 | 8 | ≥16 | - | - | - | - | - | - |
| Ureaplasma urealyticum | | | | | | | | | |
| Tetracycline | - | - | - | - | - | - | ≤1 | - | ≥2 |
A report of Susceptible (S) indicates that the antimicrobial is likely to inhibit growth of the microorganism if the antimicrobial drug reaches the concentration usually achievable at the site of infection. A report of Intermediate (I) indicates that the result should be considered equivocal, and, if the microorganism is not fully susceptible to alternative, clinically feasible drugs, the test should be repeated. This category implies possible clinical applicability in body sites where the drug product is physiologically concentrated or in situations where high dosage of drug can be used. This category also provides a buffer zone that prevents small uncontrolled technical factors from causing major discrepancies in interpretation. A report of Resistant (R) indicates that the antimicrobial drug is not likely to inhibit growth of the microorganism if the antimicrobial drug reaches the concentrations usually achievable at the infection site; other therapy should be selected.
Quality Control
Standardized susceptibility test procedures require the use of laboratory controls to monitor and ensure the accuracy and precision of supplies and reagents used in the assay, and the techniques of the individuals performing the test.1,2,3,4,5,6,7 Standard doxycycline and tetracycline powders should provide the following range of MIC values noted in Table 2. For the diffusion technique using the 30 mcg doxycycline disk or 30 mcg tetracycline disk, the criteria in should be achieved.
Table 2: Acceptable Quality Control Ranges for Susceptibility Testing for Doxycycline and Tetracycline |
| QC Strain | Minimal Inhibitory
Concentration
(mcg/mL) | Zone Diameter
(mm) | Agar Dilution
(mcg/mL) |
| Escherichia coli ATCC 25922 | | | |
| Doxycycline | 0.5 to 2 | 18 to 24 | - |
| Tetracycline | 0.5 to 2 | 18 to 25 | - |
| Eggerthella lenta ATCC 43055 | | | |
| Doxycycline | 2 to 16 | - | - |
| Haemophilus influenzae ATCC 49247 | | | |
| Tetracycline | 4 to 32 | 14 to 22 | - |
| Neisseria gonorrhoeae ATCC 49226 | | | |
| Tetracycline | - | 30 to 42 | 0.25 to 1 |
| Staphylococcus aureus ATCC 25923 | | | |
| Doxycycline | - | 23 to 29 | - |
| Tetracycline | - | 24 to 30 | - |
| Staphylococcus aureus ATCC 29213 | | | |
| Doxycycline | 0.12 to 0.5 | - | - |
| Tetracycline | 0.12 to 1 | - | - |
| Streptococcus pneumoniae ATCC 49619 | | | |
| Doxycycline | 0.015 to 0.12 | 25 to 34 | - |
| Tetracycline | 0.06 to 0.5 | 27 to 31 | - |
| Bacteroides fragilis ATCC 25285 | | | |
| Tetracycline | - | - | 0.12 to 0.5 |
| Bacteroides thetaiotaomicron ATCC 29741 | | | |
| Doxycycline | 2 to 8 | - | - |
| Tetracycline | - | - | 8 to 32 |
| Mycoplasma pneumoniae ATCC 29342 | | | |
| Tetracycline | 0.06 to 0.5 | - | 0.06 to 0.5 |
| Ureaplasma urealyticum ATCC 33175 | | | |
| Tetracycline | - | - | ≥ 8 |
Intracranial hypertension (IH, pseudotumor cerebri) has been associated with the use of tetracyclines. (See PRECAUTIONS General.)
When given over prolonged periods, tetracyclines have been reported to produce brown-black microscopic discoloration of the thyroid gland. No abnormalities of thyroid function are known to occur.
Pediatric Patients:
For all pediatric patients weighing less than 45 kg with severe or life-threatening infections (e.g. anthrax, Rocky Mountain spotted fever), the recommended dosage is 2.2 mg/kg of body weight administered every 12 hours. Children weighing 45 kg or more should receive the adult dose (see WARNINGS and PRECAUTIONS).
For pediatric patients with less severe disease (greater than 8 years of age and weighing less than 45 kg), the recommended dosage schedule is 4.4 mg per kg of body weight divided into two doses on the first day of treatment, followed by a maintenance dose of 2.2 mg per kg of body weight (given as a single daily dose or divided into twice daily doses). For pediatric patients weighing over 45 kg, the usual adult dose should be used.
The therapeutic antibacterial serum activity will usually persist for 24 hours following recommended dosage.
When used in streptococcal infections, therapy should be continued for 10 days.
Administration of adequate amounts of fluid along with capsule and tablet forms of drugs in the tetracycline class is recommended to wash down the drugs and reduce the risk of esophageal irritation and ulceration. (See ADVERSE REACTIONS)
If gastric irritation occurs, it is recommended that doxycycline be given with food or milk. The absorption of doxycycline is not markedly influenced by simultaneous ingestion of food or milk.
Studies to date have indicated that administration of doxycycline at the usual recommended doses does not lead to excessive accumulation of doxycycline in patients with renal impairment.
Uncomplicated Gonococcal Infections in Adults (Except Anorectal Infections in Men)
100 mg, by mouth, twice a day for 7 days. As an alternate single visit dose, administer 300 mg stat followed in one hour by a second 300 mg dose.
Acute Epididymo-orchitis Caused by N. gonorrhoeae
100 mg, by mouth, twice a day for at least 10 days.
Primary and Secondary Syphilis
300 mg a day in divided doses for at least 10 days.
Uncomplicated Urethral, Endocervical, or Rectal Infection in Adults Caused by Chlamydia trachomatis
100 mg, by mouth, twice a day for at least 7 days.
Nongonococcal Urethritis Caused by C. trachomatis and U. urealyticum
100 mg, by mouth, twice a day for at least 7 days.
Acute Epididymo-orchitis Caused by C. trachomatis
100 mg, by mouth, twice a day for at least 10 days.
Inhalational Anthrax (Post-Exposure)
ADULTS: 100 mg of doxycycline, by mouth, twice a day for 60 days. CHILDREN: weighing less than 45 kg 2.2 mg/kg of body weight, by mouth, twice a day for 60 days. Children weighing 45 kg or more should receive the adult dose.
Distributed by:
Encore Dermatology, Inc.
5 Great Valley Parkway,
Malvern, PA 19355 USA
1-844-848-6543
www.encorederm.com
Manufactured by:
Lupin Limited
Goa 403 722
INDIA.
June 2017
ID#: XXXXXX
DOX1133 06/17