Doxycycline ๐
โ ๏ธ Should not be given to pregnant women, breastfeeding mothers, or children <12 years (except anthrax when no alternative exists).
๐ About
Always check the BNF link here.
- ๐ A tetracycline antibiotic, usually taken once daily.
- ๐ง Swallow capsules with plenty of fluid, preferably with food (to reduce GI upset).
โ๏ธ Action
- ๐ Broad-spectrum activity against Gram-positive, Gram-negative, and atypical organisms.
- ๐ Inhibits bacterial protein synthesis (binds to 30S ribosomal subunit).
๐ Indications / Dose
- ๐ซ CAP/HAP/COPD exacerbation: 200 mg stat, then 100 mg OD for 5 days PO.
- ๐งฌ Early syphilis: 100 mg BD for 14 days.
- ๐งฌ Late syphilis: 200 mg BD for 28 days.
- ๐ Genital chlamydia: 100 mg BD for 7 days.
- ๐ท๏ธ Lyme disease: 100 mg BD for 21 days.
- โฃ๏ธ Anthrax: 100 mg BD (children only if no alternative).
- ๐ฆ Falciparum malaria (with quinine): 200 mg/day for 7 days.
- ๐ Acne / rosacea: 100 mg OD (long-term courses common).
๐ Interactions
- ๐ See BNF for full details.
- โ ๏ธ Absorption reduced by milk, antacids, and iron preparations (separate doses by several hours).
โ ๏ธ Cautions
- ๐ฆท Causes dental staining and enamel hypoplasia in children.
- ๐ Photosensitivity โ advise avoiding UV exposure and tanning lamps.
- ๐ฆด Deposition in developing bone and teeth.
โ Contraindications
- ๐ซ Pregnancy.
- ๐ซ Breastfeeding.
- ๐ซ Children <12 years (except anthrax).
- โ ๏ธ Use cautiously in renal impairment.
๐ฅ Side Effects
- ๐คข GI: nausea, vomiting, diarrhoea, antibiotic-associated colitis.
- ๐ก๏ธ Dermatological: rash, dermatitis, StevensโJohnson syndrome.
- ๐ง Neurological: idiopathic intracranial hypertension (rare but important).
- ๐งช Hepatic: hepatotoxicity, pancreatitis.
- ๐ฆท Dental: staining, enamel hypoplasia (esp. children).
๐ References