Oral Susceptible infections Adult: 150 mg bid or 300 mg once daily for 5-10 days in susceptible infections. Child: 6-40 kg: 5-8 mg/kg daily. Renal impairment: Dosage adjustment may be required. Hepatic impairment: Usual daily doses should be halved in hepatic impairment. Administration Should be taken on an empty stomach. (Take before meals.)
Roxithromycin inhibits protein synthesis by irreversibly binding to the 50s ribosomal subunits thus blocking the transpeptidation or translocation reactions of susceptible organisms resulting in stunted cell growth.
Absorption: Plasma concentrations peak after 2 hr (oral); reduced if taken after food. Bioavailability: about 50%. Distribution: Widely distributed into body tissues and fluids. Protein-binding: 96% at trough concentrations. Metabolism: Small amounts are metabolised in the liver. Excretion: Mainly via the faeces as unchanged drug and metabolites, via the urine (7-12%) and the lungs (15%).
Elimination Half-life: 8-13 hr. May be prolonged in renal and hepatic impairment, children.