tetracyklin

Tetracyklin, or tetracycline in English, is a broad-spectrum antibiotic of the tetracycline class. It is produced by certain species of Streptomyces and related actinobacteria. It is used to treat a variety of infections caused by susceptible bacteria and some intracellular pathogens.

Mechanism of action: Tetracyclins reversibly bind to the 30S ribosomal subunit, blocking the attachment of aminoacyl-tRNA to the ribosome A site. This inhibits protein synthesis and produces a bacteriostatic effect.

Indications and spectrum: Tetracyclins are active against many Gram-positive and Gram-negative bacteria and against intracellular pathogens such as Chlamydia, Mycoplasma, Rickettsia, and Coxiella. They are widely used for acne and for certain respiratory, urinary, and sexually transmitted infections, as well as some zoonotic diseases.

Pharmacokinetics and administration: They are typically given orally. Absorption of tetracycline is reduced by calcium, magnesium, iron, aluminum, or dairy products; doxycycline and minocycline have more reliable oral absorption. They distribute widely in body tissues and fluids and can cross the placenta. Elimination routes vary among agents, with differing half-lives.

Adverse effects and cautions: Common adverse effects include gastrointestinal upset and photosensitivity. Esophageal irritation can occur if not taken with enough water. Long-term use may cause dental enamel hypoplasia and tooth discoloration in developing children; tetracyclines are generally avoided during pregnancy and in children under eight. They can interact with foods and supplements containing calcium, iron, magnesium, or aluminum, reducing absorption.

Resistance and history: Resistance develops via efflux pumps and ribosomal protection mechanisms. The name derives from the four-ring structure of the molecule; tetracyclines were discovered in the mid-20th century and became clinically widespread in the 1950s.