Table of Contents
Introduction
Doxycycline is a broad-spectrum, semisynthetic tetracycline antibiotic that inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit. It is bacteriostatic and effective against gram-positive, gram-negative, and atypical organisms.
Indications
• Respiratory tract infections (atypical pneumonia)
• Acne vulgaris
• Sexually transmitted infections (chlamydia)
• Rickettsial infections
• Malaria prophylaxis
Pharmacokinetics
• Well absorbed orally
• Long half-life (once/twice daily dosing)
• Mainly excreted via feces
Adverse Effects
• GI irritation
• Photosensitivity
• Tooth discoloration (children)
• Esophagitis
Contraindications
• Pregnancy
• Children <8 years
• Tetracycline hypersensitivity
Key Point: Avoid milk, antacids, and iron (↓ absorption).
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