Antimicrobials/Tetracycline

Tetracyclines

also: doxycycline · lymecycline · tetracycline

Overview

Broad-spectrum protein-synthesis inhibitors — chlamydia, atypical pneumonia, acne, and more. Photosensitivity and the pregnancy/child contraindication are core.

Mechanism

Bind the 30S ribosomal subunit → block aminoacyl-tRNA → inhibit protein synthesis (bacteriostatic).

The agents

Doxycyclinetetracycline

oral OD/BD

Chlamydia (1st line), atypical CAP, acne, COPD exacerbation, malaria prophylaxis.

Lymecyclinetetracycline

Acne (long-term).

Adverse effects

Photosensitivityclassic

Oesophagitis (take upright with water)common

Teeth discolouration / bone (developing)serious

Benign intracranial hypertensioncommon

Avoid with isotretinoin.

Cautions & contraindications

Pregnancy & breastfeedingpregnancy

Teeth/bone.

Children <12paediatric

With oral isotretinoinall

Intracranial hypertension.

Interactions

Absorption ↓ by calcium/iron/antacids/dairy; enhances warfarin

Monitoring & kinetics

—

Oral. Take upright with water, away from divalent cations.

Choosing it

Spectrum: Broad: many Gram+/Gram−, ATYPICALS, intracellular pathogens (Chlamydia, Rickettsia, Coxiella), some protozoa (malaria prophylaxis), Lyme.

Source: BNF — Tetracyclines