Loperamide bloody diarrhea. In 1990, all formulations for children of the antidiarrheal loperamide were banned in Pakistan. Loperamide is not recommended in the UK for use during pregnancy or by nursing mothers. In the US, loperamide is classified by the FDA as pregnancy category C. Studies in rat models have shown no teratogenicity, but sufficient studies in humans have not been conducted. One controlled, prospective study of 89 women exposed to loperamide during their first trimester of pregnancy showed no increased risk of malformations. This, however, was only one study with a small sample size. Loperamide can be present in breast
Loperamide on the μ-opioid receptors in the myenteric plexus of the large intestine. Loperamide works like morphine, decreasing the activity of the myenteric plexus, which decreases the tone of the longitudinal and circular smooth muscles of the intestinal wall. This increases the time material stays in the intestine, allowing more water to be absorbed from the fecal matter. Loperamide also decreases colonic mass movements and suppresses the gastrocolic reflex. Loperamide's circulation in the bloodstream is limited in two ways. Efflux by P-glycoprotein in the intestinal wall reduces passage of loperamide, and the fraction of drug crossing is then further reduced through