DYNACIN- minocycline hydrochloride capsule
MEDICIS, The Dermatology Company

Rx Only

To reduce the development of drug-resistant bacteria and maintain the effectiveness of minocycline hydrochloride capsules and other antibacterial drugs, minocycline hydrochloride capsules 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. The structural formula is represented below:

Image from Drug Label Content

C23 H27 N3 O7 .HCl M. W. 493.94

Each minocycline hydrochloride capsule, for oral administration, contains the equivalent of 50 mg, 75 mg or 100 mg of minocycline. In addition each capsule contains the following inactive ingredients: magnesium stearate and starch (corn).

The 50 mg, 75 mg and 100 mg capsule shells contain: gelatin, silicon dioxide, sodium lauryl sulfate and titanium dioxide.

The 75 mg and 100 mg capsule shells also contain: black iron oxide.


Following oral administration of minocycline hydrochloride capsules, absorption from the gastrointestinal tract is rapid. Maximum serum concentrations following a single dose of minocycline hydrochloride to normal fasting adult volunteers were attained in 1 to 4 hours. The serum half-life in normal volunteers ranges from approximately 11 hours to 22 hours.

When minocycline hydrochloride capsules were given concomitantly with a meal which included dairy products, the extent of absorption of minocycline hydrochloride capsules was not noticeably influenced. The peak plasma concentrations were slightly decreased and delayed by one hour 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 a similar antimicrobial spectrum 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
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:

Enterobacter aerogenes
Escherichia coli
Haemophilus influenzae
Neisseria gonorrhoeae
Neisseria meningitidis


Borrelia recurrentis
Chlamydia psittaci
Chlamydia trachomatis
Fusobacterium nucletum
ssp. fusiforme
Mycobacterium marinum
Mycoplasma pneumonia
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 to 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 (µg/mL) Interpretation
≤ 4.0 Susceptible (S)
8.0 Intermediate (I)
≥16.0 Resistant (R)

For testing Haemophilus influenzae a and Streptococcus pneumoniae b:

MIC (µg/mL) Interpretation
≤ 2.0 Susceptible (S)
4.0 Intermediate (I)
≥ 8.0 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 (µg/mL) Interpretation
≤ 0.25 Susceptible (S)
0.5–1.0 Intermediate (I)
≥ 2.0 Resistant (R)

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

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