Minocycline Hydrochloride

MINOCYCLINE HYDROCHLORIDE- minocycline hydrochloride tablet, film coated
Indicus Pharma LLC

Rx Only

To reduce the development of drug-resistant bacteria and maintain the effectiveness of minocycline hydrochloride tablets and other antibacterial drugs, minocycline hydrochloride tablets should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria.


Minocycline hydrochloride, a semisynthetic derivative of tetracycline, is 4,7-Bis(dimethylamino)-1,4,4a,5,5a,6,11,12a-octahydro-3,10,12,12a-tetrahydroxy- 1,11-dioxo-2-naphthacenecarboxamide monohydrochloride. Its structural formula is:

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C23 H27 N3 O7 •HCL M.W. 493.94

Minocycline hydrochloride tablets for oral administration contain minocycline HCl equivalent to 50 mg, 75 mg or 100 mg of minocycline. In addition, 50 mg, 75 mg and 100 mg tablets contain the following inactive ingredients: Lactose Monohydrate, Magnesium Stearate, Microcrystalline Cellulose, Povidone and Sodium Starch Glycolate.

The 50 mg tablets also contain Opadry Yellow which contains: FD&C Blue No. 2, FD&C Yellow No. 5, Titanium Dioxide, Hypromellose, Polyethylene Glycol.
The 75 mg and 100 mg tablets contain Opadry Gray which contains: Titanium Dioxide, Hypromellose, Polyethylene Glycol, Polysorbate 80 and Iron Oxide Black. Minocycline Hydrochloride Tablets, 50 mg contains FD&C Yellow No. 5 (Tartrazine) as color additive.


Minocycline hydrochloride tablets are rapidly absorbed from the gastrointestinal tract following oral administration. Following a single dose of one 100 mg tablet of minocycline hydrochloride administered to 28 normal fasting adult volunteers, maximum serum concentrations were attained in 1 to 3 hours (average 1.71 hours) and ranged from 491.71 to 1292.70 ng/mL (average 758.29 ng/mL). The serum half-life in the normal volunteers ranged from 11.38 to 24.31 hours (average 17.03 hours).

When minocycline hydrochloride tablets were given concomitantly with a meal, which included dairy products, the extent of absorption of minocycline hydrochloride tablets was slightly decreased (6%). The peak plasma concentrations were slightly decreased (12%) and delayed by 1.09 hours when administered with food, compared to dosing under fasting conditions.

In previous studies with other minocycline dosage forms, the minocycline serum half-life ranged from 11 to 16 hours in 7 patients with hepatic dysfunction, and from 18 to 69 hours in 5 patients with renal dysfunction. The urinary and fecal recovery of minocycline when administered to 12 normal volunteers is one-half to one-third that of other tetracyclines.


The tetracyclines are primarily bacteriostatic and are thought to exert their antimicrobial effect by the inhibition of protein synthesis. The tetracyclines, including minocycline, have similar antimicrobial spectra of activity against a wide range of gram-positive and gram-negative organisms. Cross-resistance of these organisms to tetracyclines is common.

Minocycline has been shown to be active against most strains of the following microorganisms, both in vitro and in clinical infections as described in the INDICATIONS AND USAGE section:


Because many strains of the following gram-positive microorganisms have been shown to be resistant to tetracyclines, culture and susceptibility testing are especially recommended. Tetracycline antibiotics should not be used for streptococcal diseases unless the organism has been demonstrated to be susceptible. Tetracyclines are not the drug of choice in the treatment of any type of staphylococcal infection.

Bacillus anthracis
Listeria monocytogenes
Staphylococcus aureus
Streptococcus pneumoniae


Bartonella bacilliformis
Brucella species
Calymmatobacterium granulomatis
Campylobacter fetus
Francisella tularensis
Haemophilus ducreyi
Vibrio cholerae
Yersinia pestis

Because many strains of the following groups of gram-negative microorganisms have been shown to be resistant to tetracyclines, culture and susceptibility tests are especially recommended.

Acinetobacter species
Enterobacter aerogenes
Escherichia coli
Haemophilus influenzae
Klebsiella species
Neisseria gonorrhoeae
Neisseria meningitidis
Shigella species


Actinomyces species
Borrelia recurrentis
Chlamydia psittaci
Chlamydia trachomatis
Clostridium species
Entamoeba species
Fusobacterium nucleatum ssp. fusiforme
Mycobacterium marinum
Mycoplasma pneumoniae
Propionibacterium acnes
Treponema pallidum subspecies pallidum
Treponema pallidum subspecies pertenue Ureaplasma urealyticum

When penicillin is contraindicated, tetracyclines are alternative drugs in the treatment of infections caused by the cited microorganisms.

Susceptibility Tests

Susceptibility testing should be performed with tetracycline since it predicts susceptibility to minocycline. However, certain organisms (e.g., some staphylococci, and Acinetobacter ssp.) may be more susceptible to minocycline and doxycycline than tetracycline.

Dilution Techniques

Quantitative methods are used to determine antimicrobial minimal inhibitory concentrations (MICs). These MICs provide estimates of the susceptibility of bacteria to antimicrobial compounds. The MICs should be determined using a standardized procedure. Standardized procedures are based on a dilution method1,3 (broth or agar) or equivalent with standardized inoculum concentrations and standardized concentrations of tetracycline powder. The MIC values should be interpreted according to the following criteria:

For testing aerobic gram-negative microorganisms (Enterobacteriaceae), Acinetobacter ssp. and Staphylococcus aureus.

MIC (mcg/mL) Interpretation
≤ 4 Susceptible (S)
8 Intermediate (I)
≥ 16 Resistant (R)

For testing Haemophilus influenzae a and Streptococcus pneumoniae b:

MIC (mcg/mL) Interpretation
≤ 2 Susceptible (S)
4 Intermediate (I)
≥ 8 Resistant (R)

a. These interpretative standards are applicable only to broth microdilution susceptibility testing with Haemophilus influenzae using Haemophilus Test Medium.1

b. These interpretative standards are applicable only to broth microdilution susceptibility testing using cation-adjusted Muller-Hinton broth with 2 — 5% lysed horse blood.1

For testing Neisseria gonorrhoeae c:

MIC (mcg/mL) Interpretation
≤ 0.25 Susceptible (S)
0.5-1 Intermediate (I)
≥ 2 Resistant (R)

c. These interpretative standards are applicable only to agar dilution susceptibility testing using GC agar base and 1% defined growth supplements.1

A report of “Susceptible” indicates that the pathogen is likely to be inhibited if the antimicrobial compound in the blood reaches the concentrations usually achievable. A report of “Intermediate” 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 is physiologically concentrated or in situations where high dosage of drug can be used. This category also provides a buffer zone which prevents small uncontrolled technical factors from causing major discrepancies in interpretation. A report of “Resistant” indicates that the pathogen is not likely to be inhibited if the antimicrobial compound in the blood reaches the concentrations usually achievable; other therapy should be selected.

Standardized susceptibility test procedures require the use of laboratory control microorganisms to control the technical aspects of the laboratory procedures. Standard tetracycline powder should provide the following MIC values:

Microorganism MIC (mcg/mL)
Escherichia coli Enterococcus faecalis Staphylococcus aureus Haemophilus influenzae Streptococcus pneumoniae Neisseria gonorrhoeae ATCC 25922 0.5-2 ATCC 29212 8-32 ATCC 29213 0.25-1 ATCC 49247 4-32 ATCC 49619 0.12-0.5 ATCC 49226 0.25-1
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