Doksisyklini

Doksisyklini, commonly known as doxycycline in many languages, is a broad‑spectrum tetracycline antibiotic used in human and veterinary medicine. It is active against a wide range of Gram-positive and Gram-negative bacteria and several atypical pathogens, including Mycoplasma, Chlamydia, and Rickettsia. Clinical uses include treatment of acne and rosacea, various respiratory and urinary tract infections, sexually transmitted infections such as Chlamydia trachomatis, and vector-borne diseases like Lyme disease and rickettsial illnesses. It is also prescribed for malaria prophylaxis in travelers.

Mechanism and spectrum: Doksisyklini inhibits bacterial protein synthesis by reversibly binding to the 30S ribosomal subunit, preventing the attachment of aminoacyl‑tRNA and thereby halting production of essential proteins. This action is generally bacteriostatic rather than bactericidal.

Pharmacology: The drug is well absorbed orally, although absorption is reduced by dairy products and antacids containing calcium or magnesium. It has a relatively long half-life, which supports once‑daily dosing in many regimens, and it distributes widely to body tissues. Excretion occurs through both renal and fecal pathways.

Contraindications and safety: Doksisyklini is typically contraindicated during pregnancy and in children under 8 years due to risks of teeth discoloration and enamel hypoplasia. It should be used with caution in patients with liver or kidney impairment and in those at risk of photosensitivity. Interactions include chelation with calcium, iron, and other minerals, which can reduce absorption if taken together with certain supplements or antacids.

Adverse effects: Common adverse effects include gastrointestinal upset, esophagitis or irritation if not taken with sufficient water, photosensitivity, and increased risk of candidal infections. Less frequent but serious reactions can occur, including liver toxicity and intracranial hypertension in rare cases.