orphenadrine (Norflex)

  • Pharmacy Author:
    Omudhome Ogbru, PharmD

    Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.

  • Medical and Pharmacy Editor: Jay W. Marks, MD
    Jay W. Marks, MD

    Jay W. Marks, MD

    Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

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What is orphenadrine-oral, and how does it work (mechanism of action)?

Orphenadrine is an oral central acting skeletal muscle relaxant that is used for the treatment of acute muscle aches, pain, or spasms. The exact mechanism of action in relieving muscuar aches or spasms is not completely understood. Orphenadrine may reduce muscle spasms through actions on motor centers or the medulla in the brain. Orphenadrine does not seem to have any direct relaxant effects on skeletal muscle.

Orphenadrine is structurally related to the antihistamine diphenhydramine (Benadryl), however, its antihistamine activity is less than that of diphenhydramine. Orphenadrine also has some local anesthetic effects. The FDA approved Orphenadrine in 1959.

What brand names are available for orphenadrine-oral?

Norflex (Discontinued in the US)

Is orphenadrine-oral available as a generic drug?

GENERIC AVAILABLE: Yes

Do I need a prescription for orphenadrine-oral?

Yes

What are the side effects of orphenadrine-oral?

Side effects of orphenadrine include:

Rare but serious side effects include aplastic anemia and life threatening allergic reactions.

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What is the dosage for orphenadrine-oral?

The recommended dose is one 100 mg tablet by mouth twice daily in the morning and evening.

Which drugs or supplements interact with orphenadrine-oral?

: Orphenadrine may cause an increase in blood levels of dofetilide (Tikosyn) by decreasing its breakdown and elimination by the liver.

Orphenadrine may cause drowsiness. Taking orphenadrine with other drugs that have similar CNS depressant effects may increase the CNS depressant effects of orphenadrine.

Orphenadrine may cause anticholingeric side effects such as:

Taking medications that also have anticholingeric effects increases the anticholinergic effect of orphenadrine.

Is orphenadrine-oral safe to take if I'm pregnant or breastfeeding?

It is not known whether orphenadrine is secreted into breast milk. Orphenadrine should be avoided in pregnancy if possible.

What else should I know about orphenadrine-oral?

What preparations of orphenadrine-oral are available?

  • Orphenadrine citrate tablets: 100 mg extended release
  • Orphenadrine citrate solution for injection: 30 mg/ml

How should I keep orphenadrine-oral stored?

Tablets should be stored at room temperature, between 15 C and 30 C (59 F and 86 F).

REFERENCE: FDA Prescribing Information.

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Summary

Orphenadrine (The brand Norflex has been discontinued in the US) is a prescription drug used to treat acute muscle aches, pains, or spasms. Side effects, drug interactions, warnings, precautions, dosing, storage, pregnancy, and breastfeeding safety information is included.

Treatment & Diagnosis

Medications & Supplements

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Reviewed on 6/9/2015
References
REFERENCE: FDA Prescribing Information.

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