Loperamide

Loperamide
Clinical data
Pronunciation	/loʊˈpɛrəmaɪd/
Trade names	Imodium, others
Other names	R-18553, Loperamide hydrochloride (USAN US)
AHFS/Drugs.com	Monograph
MedlinePlus	a682280
License data	US DailyMed: Loperamide;
Pregnancy; category	AU: B3; ;
Routes of; administration	By mouth
ATC code	A07DA03 (WHO) ; A07DA05 (WHO) (oxide);
Legal status
Legal status	AU: S2 (Pharmacy medicine); BR: Class C1 (Other controlled substances); CA: OTC; UK: General sales list (GSL, OTC); US: OTC / Rx-only; SE: OTC;
Pharmacokinetic data
Bioavailability	<1%
Protein binding	~95-97%
Metabolism	Liver (extensive)
Metabolites	N-Desmethyloperamide, Loperamide-N-oxide, Loperamide carbinolamide metabolite
Onset of action	~1 hour
Elimination half-life	9–14 hours
Duration of action	Up to 3 days
Excretion	Feces (30–40%), urine (1%)
Identifiers
	IUPAC name 4-[4-(4-Chlorophenyl)-4-hydroxypiperidin-1-yl]-N,N-dimethyl-2,2-diphenylbutanamide;
CAS Number	53179-11-6;
PubChem CID	3955;
IUPHAR/BPS	7215;
DrugBank	DB00836;
ChemSpider	3818;
UNII	6X9OC3H4II;
KEGG	D08144;
ChEBI	CHEBI:6532;
ChEMBL	ChEMBL841;
CompTox Dashboard (EPA)	DTXSID6045165 ;
ECHA InfoCard	100.053.088
Chemical and physical data
Formula	C29H33ClN2O2
Molar mass	477.05 g·mol−1
3D model (JSmol)	Interactive image;
Solubility in water	The water solubility of loperamide is approximately 0.14 g/100 mL at room temperature.CID Loperamide from PubChem
	SMILES ClC1=CC=C(C2(CCN(CC2)CCC(C3=CC=CC=C3)(C(N(C)C)=O)C4=CC=CC=C4)O)C=C1;
	InChI InChI=1S/C29H33ClN2O2/c1-31(2)27(33)29(24-9-5-3-6-10-24,25-11-7-4-8-12-25)19-22-32-20-17-28(34,18-21-32)23-13-15-26(30)16-14-23/h3-16,34H,17-22H2,1-2H3; Key:RDOIQAHITMMDAJ-UHFFFAOYSA-N;

Loperamide, sold under the brand name Imodium, among others, is a medication of the opioid receptor agonist class used to decrease the frequency of diarrhea. It is often used for this purpose in irritable bowel syndrome, inflammatory bowel disease, short bowel syndrome, Crohn's disease, and ulcerative colitis. Loperamide is taken by mouth.

Common side effects include abdominal pain, constipation, sleepiness, vomiting, and dry mouth. It may increase the risk of toxic megacolon. Loperamide's safety in pregnancy is unclear, but no evidence of harm has been found. It appears to be safe in breastfeeding. It is an opioid with no significant absorption from the gut and does not cross the blood–brain barrier when used at normal doses. It works by slowing the contractions of the intestines.

Loperamide was first made in 1969 and used medically in 1976. It is on the World Health Organization's List of Essential Medicines. Loperamide is available as a generic medication. In 2023, it was the 276th most commonly prescribed medication in the United States, with more than 800,000 prescriptions.