loperamide + pink grapefruit juice

Loperamide + pink grapefruit juice refers to the co-administration of loperamide, an over-the-counter antidiarrheal medication, with pink grapefruit juice. Loperamide is a synthetic opioid that acts as a μ-opioid receptor agonist in the gut, slowing intestinal motility and reducing diarrhea. Pink grapefruit juice contains furanocoumarins (notably 6',7'-dihydroxybergamottin) that are potent inhibitors of cytochrome P450 3A4 (CYP3A4) and P-glycoprotein (P-gp), enzymes responsible for metabolizing many drugs including loperamide. When taken together, pink grapefruit juice significantly increases systemic exposure to loperamide by inhibiting its intestinal metabolism and efflux, raising plasma concentrations and increasing the risk of serious adverse effects such as cardiac arrhythmias (including long QT syndrome) and central opioid toxicity[1][2][4][5][6]. This combination is not an approved therapy but has been reported in cases of drug misuse or abuse.

Other names

loperamide with grapefruit juiceloperamide and grapefruit juice