Effects of oral pirenzepine on gastric emptying and antral motor activity in healthy man.

UNLABELLED

Pirenzepine (PIR), in contrast to classical antimuscarinic drugs, shows heterogeneity of binding that corresponds with the pharmacological activity: gastric secretion is inhibited by low doses, whereas higher doses are needed to inhibit gastrointestinal motility. This study investigated the effects of oral PIR on gastric emptying and antral motor activity. 20 healthy men (mean age 24.9 yr) participated in two experimental sessions, one week apart. According to a cross-over double blind design they received, three and a half days prior to the studies, either 50 mg PIR twice daily or placebo (PLA). A semisolid test meal labelled with 150 MBq 99mTc hSA was administered. A gamma camera coupled to a computer monitored modulation depth (MD), frequency (FR), and propagation velocity (PV) of antral contractions together with gastric emptying rate (GE) according to a modification of Akkerman's technique. PIR decreased MD (PLA: 21.2 +/- 1.7 SEM%; PIR: 17.2 +/- 1.5%; P less than 0.005) and increased FR (PLA: 3.12 +/- 0.05 cycles/min; PIR: 3.29 +/- 0.07 c/min; P less than 0.005) significantly whereas PV was accelerated (PLA: 2.9 +/- 0.2 mm/sec; PIR: 3.1 +/- 0.3 mm/sec; n.s.) and GE delayed only slightly (PLA: 50.4 +/- 8.5 kcpm; PIR: 35.5 +/- 6.0 kcpm; n.s.). PIR produced more frequent stools in three and accommodation difficulties and a dry mouth in each two subjects. PLA caused no side effects.

CONCLUSION

PIR delays GE insignificantly despite of considerable effects on antral motility.