Doxy

# Doxy ## Overview - **Classification**: Tetracycline antibiotic - **Mechanism**: Reversibly binds to the bacterial 30S ribosomal subunit, inhibiting protein synthesis. Also has anti-inflammatory properties. ## Primary Indications 1. **Bacterial Infections**: Respiratory, urinary, skin/soft tissue, GI, STIs (e.g., Chlamydia, Gonorrhea). 2. **Acne Vulgaris**: Moderate to severe inflammatory acne (anti-inflammatory doses). 3. **Malaria Prophylaxis**: Prevention of malaria in endemic areas. 4. **Lyme Disease**: Treatment of early disease and prophylaxis post-tick bite. 5. **Rickettsial Infections**: Rocky Mountain Spotted Fever (RMSF), typhus. ## Adult Dosing ### Standard Dosing **Most Susceptible Infections (e.g., STIs, mild-mod skin/respiratory)** - **Dose**: **100 mg** - **Frequency**: Every 12 hours - **Route**: Oral (PO) or Intravenous (IV) - **Duration**: Typically 7-14 days (varies by infection) **Acne Vulgaris (Anti-inflammatory)** - **Dose**: **20 mg** (for Oracea) or **50 mg** - **Frequency**: Once or twice daily - **Route**: Oral (PO) - **Duration**: Several months, long-term **Malaria Prophylaxis** - **Dose**: **100 mg** - **Frequency**: Once daily - **Route**: Oral (PO) - **Duration**: Start 1-2 days pre-travel, continue 4 weeks post-travel. **Lyme Disease (Early)** - **Dose**: **100 mg** - **Frequency**: Twice daily - **Route**: Oral (PO) - **Duration**: 10-21 days (varies by stage) ### Dose Adjustments - **Renal Impairment**: **No dose adjustment** needed. Primarily excreted via non-renal routes. - **Hepatic Impairment**: Use with **caution** in severe dysfunction; monitor for accumulation. - **Elderly Patients**: No specific dose adjustment. Monitor for adverse effects. ## Pediatric Dosing **Note**: Doxycycline is generally **not recommended for children <8 years old** due to permanent tooth discoloration and enamel hypoplasia. However, for severe or life-threatening infections (e.g., RMSF, anthrax, cholera), the benefits may outweigh the risks. ### Neonates (0-28 days) - **Dose**: **Generally avoided**. Only in dire, life-threatening situations. - **Special Notes**: High risk of permanent tooth discoloration, enamel hypoplasia, and bone growth inhibition. Consult ID specialist. ### Infants (1-12 months) - **Dose**: **Generally avoided**. Consider only for severe/life-threatening infections (e.g., RMSF). - **If used (off-label)**: **2.2 mg/kg/dose** - **Frequency**: Every 12 hours - **Maximum**: **100 mg/dose** or **200 mg/day** (whichever is lower, or specific indication max) - **Special Notes**: High risk of permanent tooth discoloration. ### Children (1-12 years) - **For severe/life-threatening infections (e.g., RMSF, anthrax):** - **Dose**: **2.2 mg/kg/dose** - **Frequency**: Every 12 hours - **Maximum**: **100 mg/dose** - **For Lyme Disease prophylaxis post-tick bite (single dose):** - **Dose**: **4.4 mg/kg** (single dose) - **Maximum**: **200 mg** (single dose) - **Special Notes**: Avoid routine use. Liquid suspension may be available. ### Adolescents (13-18 years) - **Dose**: Follow **adult dosing** guidelines. - **Frequency**: As per indication. - **Maximum**: **200 mg/day** (standard); **300 mg/day** (severe infections). - **Special Notes**: Risk of tooth discoloration minimal if permanent teeth have erupted. ## Safety Information ### Contraindications - **Absolute**: Hypersensitivity to doxycycline or other tetracyclines. - **Absolute**: Pregnancy (Category D) and breastfeeding (generally avoid). - **Absolute**: Children <8 years (unless for severe/life-threatening infections). - **Relative**: Severe hepatic impairment. ### Common Adverse Effects - **Very Common (>10%)**: Photosensitivity (severe sunburn-like reaction). - **Common (1-10%)**: Nausea, vomiting, diarrhea, esophageal irritation/ulceration, abdominal pain. - **Common (1-10%)**: Vaginal candidiasis, superinfections. - **Serious but Rare**: Intracranial hypertension (pseudotumor cerebri), Stevens-Johnson syndrome, pseudomembranous colitis, hepatotoxicity. ### Key Drug Interactions - **Antacids, Iron, Calcium, Magnesium, Bismuth**: Decreased doxycycline absorption. Separate by **2-3 hours**. - **Oral Contraceptives**: May decrease efficacy. Advise back-up contraception. - **Warfarin**: May potentiate anticoagulant effect. Monitor INR closely. - **Retinoids (oral isotretinoin, acitretin)**: Increased risk of intracranial hypertension. Avoid co-administration. - **Penicillins**: May interfere with bactericidal action. Avoid concurrent use. ## Monitoring & Follow-up - **Before Treatment**: Pregnancy test for women of childbearing potential. - **During Treatment**: Monitor for signs of photosensitivity, GI upset, or superinfection. - **Clinical Signs**: Instruct patient to report severe headache, vision changes, severe diarrhea, or rash immediately. ## Clinical Pearls - 💡 **Tip 1**: Take with a **full glass of water** and **remain upright for 30-60 minutes** to prevent esophageal irritation/ulceration. - 💡 **Tip 2**: Advise patients to **avoid direct sun exposure** and use sunscreen/protective clothing due to photosensitivity. - 💡 **Tip 3**: Take with food (non-dairy) if GI upset occurs, but **avoid dairy products, antacids, or iron supplements** within 2-3 hours of dose. - 💡 **Tip 4**: Doxycycline is a preferred agent for suspected RMSF in **all age groups**, despite the tooth discoloration risk, due to the severity of the disease. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.