Doessmoking influence thepharmacokinetics and pharmacodynamics oftheH2-receptor antagonist famotidine?

Twelvehealthy habitual cigarette smokers andeight non-smokers participated ina double-blind placebo controlled study todetermine theeffect ofsmoking onthe pharmacokinetics andpharmacodynamics oftheH2-receptor antagonist famotidine. Insmokers, cigarette smoking wasstandardised andstarted 1hbefore (A), or2hafter (B)drugadministration, orwasprohibited (C).Intragastric pH-levels (IGpH) were measured withanambulatory pH-recorder. Famotidine (40mg orally) significantly raised median 22hIGpHinnon-smokers andsmokers inallstudy periods. Thesmoking sequence (A,B,C)didnotsignificantly influence median22hIGpHinbothplacebotreated andfamotidine-treated smokers, andnosignificant difference inmedian22h IGpHwasshownbetween smokers andnon-smokers. Plasma drugconcentrations were similar inthevarious experiments, although famotidine wasdetected earlier inplasma fromnon-smokers compared withsmokers (P< 0.05). Smoking didnotinterfere significantly withthepharmacokinetics andpharmacodynamics offamotidine.