Orphenadrine

Orphenadrine

Clinical data
Trade names	Generic; many brand names worldwide
AHFS/Drugs.com	Monograph
MedlinePlus	a682162
Pregnancy category	AU: B2 US: C (Risk not ruled out)
Routes of administration	Oral, intravenous, intramuscular
ATC code	M03BC01 (WHO) N04AB02 (WHO)
Legal status
Legal status	AU: S4 (Prescription only) CA: OTC UK: POM (Prescription only) US: ℞-only
Pharmacokinetic data
Bioavailability	90%
Protein binding	95%
Metabolism	Hepatic demethylation
Biological half-life	13-20 hours
Excretion	Renal and biliary
Identifiers
IUPAC name N,N-dimethyl-2-[(2-methylphenyl)- phenyl-methoxy]-ethanamine
CAS Number	83-98-7 Y
PubChem (CID)	4601
IUPHAR/BPS	7251
DrugBank	DB01173 Y
ChemSpider	4440 Y
UNII	AL805O9OG9 Y
KEGG	D08305 Y
ChEBI	CHEBI:7789 Y
ChEMBL	CHEMBL900 Y
ECHA InfoCard	100.001.372
Chemical and physical data
Formula	C18H23NO
Molar mass	269.381 g/mol
3D model (Jmol)	Interactive image
SMILES O(CCN(C)C)C(c1ccccc1)c2ccccc2C
InChI InChI=1S/C18H23NO/c1-15-9-7-8-12-17(15)18(20-14-13-19(2)3)16-10-5-4-6-11-16/h4-12,18H,13-14H2,1-3H3 Y Key:QVYRGXJJSLMXQH-UHFFFAOYSA-N Y

Orphenadrine (sold under many brand names worldwide) is an anticholinergic drug of the ethanolamine antihistamine class; it is closely related to diphenhydramine. It is used to treat muscle pain and to help with motor control in Parkinson's disease, but has largely been superseded by newer drugs. It was discovered and developed in the 1940s.

As of 2015 the cost for a typical month of medication in the United States is US$25 to 50.

Orphenadrine is used to relieve pain caused by muscle injuries like strains and sprains in combination with rest and physical therapy. A 2004 review found little clinical evidence for the safety or efficacy of orphenadrine for this use.

Orphenadrine and other muscle relaxants are sometimes used to treat pain arising from rheumatoid arthritis but there is no evidence they are effective for that purpose.

A 2003 Cochrane Review of the use of anticholinergic drugs to improve motor function in Parkinson's disease found that as a class, the drugs are useful for that purpose; it identified one single-site randomised, cross-over study of orphenadrine vs placebo. Orphenadrine and other anticholinergics have largely been superseded by other drugs; they have a use in alleviating motor function symptoms, and appear to help about 20% of people with Parkinson's.

Orphenadrine has the side effects of the other common antihistamines in large part. Stimulation is somewhat more common than with other related antihistamines, and is especially common in the elderly. Common side effects include dry mouth, dizziness, drowsiness, upset stomach or vomiting, constipation, urine retention, blurred vision, and headache. Its use in Parkinson's is especially limited by these factors.

People with glaucoma, digestive problems like peptic ulcers or bowel obstruction, or sphincter relaxation disorders, or with enlarged prostate, bladder problems, or myasthenia gravis, should not take this drug.