Pirenzepine Antacids

Mylanta reduces the bioavailability of pirenzepine by about 30%. Another antacid, Trigastril, modestly increases the bioavailabilily of pirenzepine, but these changes are probably of little clinical importance. 

The AUC of a single 50-mg dose of pirenzepine was redueed by about 30% in 20 healthy subjeets by 30 mL of Mylanta (aluminium/magnesi-um hydroxide and simeticone). The antacid reduced the peak plasma levels of pirenzepine by about 45%. Another study in 10 healthy subjects found that the AUC of a single 50-mg dose of pirenzepine was increased by almost 25% by 10 mL of an antacid (Trigastril, aluminium/magnesi-um hydroxide, calcium carbonate). In practical terms these modest changes in bioavailability are probably too small to matter. 

Matzek KM, NfacGregor TR, Keims JJ, Vinocur M. Effect of food and antacids on the oral ab-sOTpticfi of pirenzepine in man. IntJPharmaceutics 9Z6) 28,151-5. 

Vergin H, Herrlinger C, Gugler R. Effect of an alum inium-hydroxide containing antacid on the oral bioavailability of pirenzepine. Arzneimittelforschung (1989) 39, 520-3. 

---