chapter
Antibiotics – tetracyclines
Pages 3

Avoid co-administration with buffered didanosine preparations. Consider changing to enteric-coated didanosine tablets

TETRACYCLINES CALCIUM ↓ antibiotic levels ↓ absorption Separate doses by at least 2 hours TETRACYCLINES DAIRY PRODUCTS ↓ antibiotic levels ↓ absorption (due to the calcium

content of dairy produce) Separate doses by at least 2 hours

TETRACYCLINES DIURETICS Possible risk of renal toxicity Additive effect Some recommend avoiding coadministration; others advise monitoring renal function closely. Doxycycline is likely to be less of a problem

DOXYCYCLINE H2 RECEPTOR BLOCKERS ↓ plasma concentrations and risk of treatment failure

↓ absorption of cephalosporin as ≠ gastric pH

Avoid concomitant use. If unable to avoid combination, take H2 antagonists at least 2-3 hours after cephalosporin. Consider an alternative antibiotic or separate the doses by at least 2 hours and give with an acidic drink, e.g. carbonated drink; ≠ dose may be required

TETRACYCLINES IRON – ORAL 1. ↓ iron levels when iron given orally 2. ↓ plasma concentrations of these drugs, with risk of therapeutic failure

1. ↓ absorption 2. Iron chelates with tetracyclines and ↓ their absorption

1. Separate doses as much as possible – monitor FBC closely 2. Separate doses of other drugs as much as possible and monitor their effect

TETRACYCLINES KAOLIN ↓ tetracycline levels ↓ absorption Separate doses by at least 2 hours TETRACYCLINE LIPID-LOWERING DRUGS –

ANION EXCHANGE RESINS ↓ levels of tetracycline and possible therapeutic failure

Tetracycline binds with colestipol and colestyramine in the gut therefore ↓ its absorption

Dosing should be as separate as possible