Overview
Minocycline is a broad-spectrum tetracycline-class antibiotic effective against various bacterial infections including respiratory, skin, and sexually transmitted diseases. It works by inhibiting bacterial protein synthesis and has anti-inflammatory properties that make it useful for acne treatment. Due to its unique pharmacokinetics, it requires specific dosing different from other tetracyclines.
Mechanism of Action
Minocycline inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit, preventing aminoacyl-tRNA from attaching to the ribosome acceptor site. This bacteriostatic action disrupts bacterial growth and replication.
Indications
- Rocky Mountain spotted fever and other rickettsial infections
- Respiratory tract infections caused by Mycoplasma pneumoniae and Haemophilus influenzae
- Sexually transmitted infections including chlamydia, gonorrhea, and syphilis (when penicillin contraindicated)
- Skin and skin structure infections including acne vulgaris
- Atypical mycobacterial infections (Mycobacterium marinum)
- Meningococcal carrier state eradication
- Various other bacterial infections including plague, tularemia, and brucellosis
Common Doses
- 50 mg capsules
- 75 mg capsules
- 100 mg capsules
Dosage
Usual adult dose: 200 mg initially, then 100 mg every 12 hours. Pediatric dose (above 8 years): 4 mg/kg initially followed by 2 mg/kg every 12 hours. Capsules should be swallowed whole with adequate fluids to prevent esophageal irritation. Dosage adjustment required in renal impairment.
Contraindications
- Hypersensitivity to minocycline or other tetracyclines
- Use during tooth development (last half of pregnancy, infancy, childhood to age 8 years) due to permanent tooth discoloration risk
Side Effects
- Gastrointestinal: Nausea, vomiting, diarrhea, esophagitis, pseudomembranous colitis
- Dermatologic: Photosensitivity, skin pigmentation changes, Stevens-Johnson syndrome, toxic epidermal necrolysis
- Hepatic: Hepatitis, liver failure, jaundice
- Renal: Increased BUN, acute renal failure
- Neurologic: Dizziness, vertigo, headache, benign intracranial hypertension
- Hypersensitivity: Anaphylaxis, lupus-like syndrome, serum sickness-like reactions
- Hematologic: Leukopenia, thrombocytopenia, eosinophilia
Interactions
- Antacids containing aluminum, calcium, or magnesium impair absorption
- Oral contraceptives may have reduced effectiveness
- Warfarin and other anticoagulants may require dosage adjustment
- Penicillins - avoid concurrent use due to antagonism
- Isotretinoin - increased risk of pseudotumor cerebri
- Ergot alkaloids - increased risk of ergotism
Counseling Points
- Take with adequate fluids to prevent esophageal irritation and ulceration
- Avoid taking with antacids, calcium, iron, or magnesium supplements
- Use sunscreen and protective clothing due to photosensitivity risk
- Report severe diarrhea, skin rashes, or vision changes immediately
- Complete full course of therapy even if symptoms improve
- Do not take during pregnancy or while breastfeeding without medical advice
- Be cautious when driving or operating machinery due to potential dizziness