PANTOPRAZOLE, A NEW PROTON-PUMP INHIBITOR, HAS A PRECISE AND PREDICTABLE PROFILE OF ACTIVITY

Mechanism of action of pantoprazole: Pantoprazole, a new proton-pump i nhibitor, is a drug which demonstrates precision from the molecular le vel to the patient. Like other H+,K+-ATPase inhibitors it has in-built selectivity because it accumulates in the acidic compartment of the p arietal cell and has to be acid-activated before it acts on the proton pump. Stability of pantoprazole: Pantoprazole is chemically more stab le than the other proton-pump inhibitors, particularly at near neutral pH, and therefore is unlikely to interact with thiol-containing prote ins outside the parietal cell. This acid stability may also account fo r its highly selective binding to the two cysteine groups located in t he proton-pumping pathway of the enzyme. Conclusions: Pantoprazole is characterized by a degree of pharmacokinetic precision not associated with the other drugs. It shows linear kinetics after oral and intraven ous administration. It has a high and constant bioavailability (approx imately 77%) which does not change on multiple dosing, so that maximum blood levels are achieved after the first dose. Bioavailability is no t altered by concomitant antacid administration, and dose adjustment i s not required in elderly patients or those with chronic renal impairm ent. Extensive studies in man have found no interaction with other dru gs. Because of this pharmacokinetic profile, a standard dose of 40 mg is optimal and can be used with confidence in subgroups of patients to give a predictable therapeutic effect.