Minocycline

# Minocycline ## Overview - **Classification**: Tetracycline antibiotic - **Mechanism**: Inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit. Bacteriostatic action against susceptible organisms. ## Primary Indications 1. **Acne Vulgaris** - Moderate to severe inflammatory acne. 2. **Bacterial Infections** - Respiratory tract, urinary tract, skin and soft tissue infections, STIs (e.g., Chlamydia). 3. **Rickettsial Infections** - Rocky Mountain spotted fever, typhus fever. ## Adult Dosing ### Standard Dosing **Most Bacterial Infections** (e.g., Chlamydia, Gonorrhea, Skin/Soft Tissue) - **Dose**: **200 mg** initial dose, then **100 mg** - **Frequency**: **every 12 hours** - **Route**: Oral - **Duration**: Typically 7-14 days, or as clinically indicated. **Acne Vulgaris** - **Dose**: **50 mg** to **100 mg** - **Frequency**: **once daily** or **every 12 hours** - **Route**: Oral - **Duration**: Weeks to months (e.g., 6-12 weeks for initial improvement). ### Dose Adjustments - **Renal Impairment**: No specific dose adjustment generally needed, but use with caution. Monitor for increased BUN/azotemia. - **Hepatic Impairment**: Use with caution. Monitor liver function tests. Dose reduction may be necessary in severe impairment. - **Elderly Patients**: No specific dose adjustment based solely on age. Monitor renal and hepatic function. ## Pediatric Dosing **Note**: Minocycline is generally not recommended for children under 8 years due to the risk of permanent tooth discoloration and bone growth inhibition. ### Neonates (0-28 days) - **Contraindicated**: Due to risk of permanent tooth discoloration, enamel hypoplasia, and bone growth inhibition. ### Infants (1-12 months) - **Contraindicated**: Due to risk of permanent tooth discoloration, enamel hypoplasia, and bone growth inhibition. ### Children (1-12 years) - **Age < 8 years**: **Contraindicated**. - **Age 8-12 years (if alternative antibiotics are not suitable)**: - **Dose**: **4 mg/kg** initial dose, then **2 mg/kg** - **Frequency**: **every 12 hours** - **Maximum**: **200 mg/day** - **Special Notes**: Use only when benefits outweigh risks. Counsel on potential for permanent tooth discoloration. ### Adolescents (13-18 years) - **Dose**: Follow adult dosing recommendations. - **Maximum**: Adult maximum dose (typically **400 mg/day** for infections). - **Special Notes**: Counsel on photosensitivity and potential for skin discoloration with long-term use. ## Safety Information ### Contraindications - **Absolute**: Hypersensitivity to minocycline or any tetracycline. - **Absolute**: Children **under 8 years of age** (due to permanent tooth discoloration). - **Absolute**: Pregnancy (2nd and 3rd trimesters) and breastfeeding. - **Relative**: Severe renal or hepatic impairment. ### Common Adverse Effects - **Very Common (>10%)**: Nausea, vomiting, diarrhea, dizziness, vertigo (especially with initial doses). - **Common (1-10%)**: Photosensitivity, skin discoloration (blue-gray pigment), headache, rash. - **Serious but Rare**: Pseudotumor cerebri (benign intracranial hypertension), DRESS syndrome, SJS, lupus-like syndrome, hepatotoxicity, esophageal ulceration, bone marrow suppression. ### Key Drug Interactions - **Antacids/Iron/Calcium/Magnesium**: Decreased minocycline absorption. Administer minocycline 2 hours before or 4 hours after these agents. - **Oral Contraceptives**: May decrease efficacy of oral contraceptives. Advise backup contraception. - **Warfarin**: Enhanced anticoagulant effect. Monitor INR closely. - **Isotretinoin and other Retinoids**: Increased risk of pseudotumor cerebri. Avoid concomitant use. - **Methoxyflurane**: Potentially fatal renal toxicity. Avoid concomitant use. ## Monitoring & Follow-up - **Before Treatment**: Baseline liver function tests (LFTs) if long-term therapy is anticipated or hepatic impairment suspected. Renal function, especially in elderly or those with comorbidities. - **During Treatment**: Monitor for signs/symptoms of adverse effects (e.g., headache/vision changes for pseudotumor, skin/eye yellowing for hepatotoxicity, rash). - **Clinical Signs**: Watch for persistent headache, blurred vision, severe dizziness, severe skin reactions, dark urine, or yellowing skin/eyes. ## Clinical Pearls - 💡 **Administration**: Take with a full glass of water to prevent esophageal irritation/ulceration. Avoid lying down for at least 30-60 minutes after dose. - 💡 **GI Upset**: Can be taken with food or milk to minimize GI upset, but avoid taking with calcium/iron supplements. - 💡 **Photosensitivity**: Counsel patients to avoid excessive sun exposure and use sunscreen due to risk of severe sunburn. - 💡 **Discoloration**: May cause permanent tooth discoloration in children <8 years. Long-term use in adults can cause blue-gray skin, nail, or mucous membrane discoloration. - 💡 **Dizziness**: Dizziness/vertigo is common; counsel patients on driving/operating machinery. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.