Minocycline (Minocin)

• Generic name: Minocycline
• Trade names: Dynacin, Minocin, Myrac, Solodyn, Vectrin
• Dosages:
  Tablets 50 mg, 75 mg, 100 mg
  Capsules 50 mg, 100 mg
  Powder for injection, cryodesiccated 100 mg
  Microspheres, sustained-release 1 mg
• Pharmacologic category: Tetracycline antibiotic
• FDA approved: June 30, 1971
• Pregnancy risk factor: D

Minocycline is a tetracycline antibiotic. Minocycline is used to treat a wide variety of bacterial infections, such as urinary tract infections, severe acne, gonorrhea, tick fever, chlamydia, and others.

Common side effects associated with its use are nausea, vomiting, skin rashes, dizziness, photosensitivity.

Minocycline is highly active in the pilosebaceous complex, due to its great lipophilicity, and therefore it has been used in the treatment of moderate to severe papulo-pustular acne for a long time. It is widely used in persons with acne who fail to respond to other treatments.

Most strains of P. acnes are sensitive to minocycline. The percentage of P. acnes resistant strains is still less than 5%1. It is very important because of increasing rate of P. acnes resistance to other tetracyclines.

Minocycline can be taken with food and causes less GI upset than other tetracyclines and can reduce treatment failures due to poor compliance.

Minocycline is very effective in reducing inflammatory acne lesions. It is even useful in inhibiting granuloma formation. Minocycline should be started at 100 mg twice daily, but clearing may be maintained at doses as low as 100 mg every 2-3 days.

Minocycline and other tetracyclines are known and used in medicine primarily for their antibiotic properties. However, it has various anti-inflammatory actions that may make it useful for treating rheumatoid arthritis. The use of antibiotic therapy for rheumatoid arthritis was pioneered some 50 years ago by Dr Thomas McPherson Brown, who claimed that the disease was caused by Mycoplasma infection in the joints.

Recent research shows that, besides their antibiotic effects, minocycline can block the actions of enzymes called metalloproteinases that play a role in the destruction of bone and cartilage in the joints in rheumatoid arthritis. There is also evidence that this drug can dampen or modify some of the body's inflammatory responses.

Results of a 48-week multicenter clinical study2 of 219 adults with rheumatoid arthritis show that minocycline reduces joint pain and swelling and is safe in patients with mild to moderate disease. Minocycline may improve control of disease activity and provide relief from swollen, tender joints. Minocycline is not currently FDA-approved for arthritis and while it could be as effective as antimalarials or sulfasalazine, many rheumatologists use it in milder cases.

• Elimination half-life: 16 hours (range: 11-23 hours)
• Metabolism: Hepatic to inactive metabolites
• Excretion: excreted via the faeces primarily and via the urine at a low rate.

• Less phototoxic than other tetracyclines. Studies indicate that photosensitivity occurs rarely with minocycline hydrochloride4.
• Less likelihood of bacterial resistance. Bacterial cell membranes are surrounded by a lipid layer (a water insoluble, fatty substance which surrounds the cell and provides it with fuel). As a means of resisting antibiotics, the cells increase the thickness of this lipid layer. Minocycline has the best penetrating ability5.
• Extended spectrum of antimicrobial activity. Minocycline is active against many tetracycline resistant strains of organisms such as staphylococci, streptococci and E. coli.
• Greater tissue penetration. Minocycline achieves much higher concentrations in the tissues than other tetracyclines. Equivalent blood and tissue levels achieved whether administered intravenously or orally.
• The long half-life allows for a less frequent dosing regimen.
• Minocycline is one of the few drugs that are highly active against methicillin-resistant Staphylococcus aureus (MRSA).

• Expensive. Minocycline is quite expensive.
• Intracranial hypertension. Benign intracranial hypertension has been documented in association with minocycline6. Benign intracranial hypertension (BIH) is a rare but potentially serious condition. Benign intracranial hypertension, also known as pseudotumour cerebri, involves a persistent rise in cerebrospinal fluid pressure. It is characterised by headache, nausea, vomiting and papilloedema with occasional sixth-nerve palsy.
• Serious hypersensitivity reactions. Minocycline can cause serum sickness like reaction (SSLR).
• Lupus-like syndrome. Minocycline may produce a lupus-like syndrome. Also rarely, long-term treatment may engender a lupus- like syndrome that is antinuclear-antibody positive and that clears upon discontinuation of the drug.
• Vestibular dysfunction. Minocycline is associated with a high rate of vestibular side effects, such as dizziness, nausea, vomiting, vertigo, and anorexia 7. This is caused by vestibular or CNS toxicity and is of such severity and frequency that CDC has changed recommendations on its non-essential use.
• Hyperpigmentation. Minocycline seems to be unique within the tetracyclines class in causing potentially irreversible slate-grey hyperpigmentation of the skin.

• Rosacea is a chronic disease that affects the face skin and sometimes the eyes. Tetracyclines are the most common antibiotics used to treat rosacea. The papules and pustules symptomatic of rosacea may respond quickly to treatment, but the redness and flushing are less likely to improve.
• Osteoporosis. Minocycline has been shown to increase bone mineral density, improve bone strength and formation, and slow bone resorption in old laboratory animals with surgically-induced menopause3.
• Lyme disease
• Sarcoidosis, a systemic inflammatory disease affecting the skin, lungs and lymph nodes, among other tissues.

Minocycline is a tetracycline with antibacterial activity against some Gram-negative and Gram-positive organisms. The action is primarily bacteriostatic and it is thought to exert its antimicrobial effect by the inhibition of protein synthesis.

Neuroprotective effects
Minocycline is thought to inhibit cell death in the central nervous system by reducing the activity of proapoptotic and proinflammatory enzymes. The drug has been shown to be neuroprotective in animal models of stroke, trauma and a variety of neurodegenerative diseases.

• Minocycline ratings, comments by patients on DrugLib.com
• User reviews on DailyStrength (68% success for acne treatment)
• Minocycline user reviews at Drugs.com (user's rating for acne - 7.2 points)
• Minocycline Reviews - on Acne.org
• Minocycline not working discussion on MedHelp

• 1. Maffeis L, Veraldi S. Minocycline (Minocin) in the treatment of acne: latest findings. G Ital Dermatol Venereol. 2010 Jun;145(3):425-9.
• 2. Tilley BC, Alarco'n GS, Heyse SP, Trentham DE, Neuner R, Kaplan DA, Clegg DO, Leisen JC, Buckley L, Cooper SM, Duncan H, Tuttleman M, Fowler SE. Minocycline in rheumatoid arthritis. A 48-week, double-blind, placebo-controlled trial. MIRA Trial Group. Ann Intern Med. 1995 Jan 15;122(2):81-9. PubMed
• 3. Williams S, Wakisaka A, Zeng QQ, Barnes J, Martin G, Wechter WJ, Liang CT. Minocycline prevents the decrease in bone mineral density and trabecular bone in ovariectomized aged rats. Bone. 1996 Dec;19(6):637-44. PubMed
• 4. Glette J, Sandberg S. Phototoxicity of tetracyclines as related to singlet oxygen production and uptake by polymorphonuclear leukocytes. Biochem Pharmacol. 1986 Sep 1;35(17):2883-5. PubMed
• 5. Eady EA, Cove JH, Holland KT, Cunliffe WJ. Superior antibacterial action and reduced incidence of bacterial resistance in minocycline compared to tetracycline-treated acne patients. Br J Dermatol. 1990 Feb;122(2):233-44. PubMed
• 6. Lander CM. Minocycline-induced benign intracranial hypertension. Clin Exp Neurol. 1989;26:161-7. PubMed
• 7. Jacobson JA, Daniel B. Vestibular reactions associated with minocycline. Antimicrob Agents Chemother. 1975 Oct;8(4):453-6. PubMedCentral

Last updated: November, 2011