MINOMYCIN

What it is

MINOMYCIN contains minocycline hydrochloride dihydrate equivalent to 50 mg of minocycline as the active ingredient. Minocycline hydrochloride dihydrate is a semisynthetic derivative of the broad spectrum antibiotic, tetracycline. Like other tetracyclines, minocycline is primarily bacteriostatic and is thought to exert its antimicrobial effect by protein synthesis inhibition.

Approved indications

— Infections due to Escherichia coli, Enterobacter aerogenes, Haemophilus influenzae, Klebsiella and Proteus, provided that they have been shown by bacteriological testing to be susceptible to minocycline. — Infections due to Streptococcus pyogenes (group A haemolytic) and Streptococcus faecalis, provided the organisms have definitely been shown to be sensitive. — Staphylococcal infections only if other suitable agents are not available and the organism has been shown to be sensitive to minocycline. — Tetracycline resistant acne.

Dosing overview

The usual dosage of minocycline for adults is 200 mg initially followed by 100 mg every twelve hours. Therapy should be continued for at least 24 to 48 hours after symptoms and fever have subsided. In tetracycline resistant acne the dosage is 100 mg daily, given preferably as 50 mg twice daily.

Key safety warnings

The use of tetracyclines during tooth development (last half of pregnancy, infancy and childhood to the age of 8 years) may cause permanent discolouration of the teeth (yellow–grey–brown), with this adverse reaction more common during long-term use but observed following repeated short-term courses. Minocycline use has been associated with blue-black cutaneous hyperpigmentation affecting most areas of the body including the face, and appears more likely to occur in patients with certain immunological conditions (rheumatoid arthritis, pemphigus and pemphigoid in particular), acne vulgaris and with prolonged use and/or higher doses. In many cases the cutaneous pigmentation is reversible or partially reversible on discontinuation of minocycline, though complete resolution may take several months or years. Photosensitivity manifested by an exaggerated sunburn reaction has been observed in some individuals taking tetracyclines, and patients prone to exposure to direct sunlight or ultraviolet light should be advised that treatment should be discontinued at the first evidence of skin erythema. Antibiotic associated pseudomembranous colitis has been reported with minocycline, with a toxin produced by Clostridium difficile as the primary cause, and severity ranging from mild to life threatening. Central nervous system side effects including light-headedness, dizziness or vertigo have been reported with minocycline therapy, and patients who experience these symptoms should be cautioned about driving vehicles or using hazardous machinery. Pseudotumour cerebri (benign intracranial hypertension) in adults has been associated with the use of minocycline, with usual clinical manifestations of headache and blurred vision.

Contraindications

Hypersensitivity to any of the tetracyclines. Severe renal insufficiency. Systemic lupus erythematosus. Concomitant treatment of tetracyclines with vitamin A or retinoids such as isotretinoin or etretinate is contraindicated due to rare cases of benign intracranial hypertension reported after both drug classes.

Regulatory history

MINOMYCIN 50 minocycline 50 mg tablet was first listed on the Australian Register of Therapeutic Goods on 7 December 1993.