Motofen

A comprehensive article about the subgroup of anti-diarrhoeal drugs including Motofen can be found as the article Diphenoxylate.

Motofen is the brand name for an antiperistaltic anti-diarrheal medication, containing 1.0 mg difenoxin HCl and 0.025 mg atropine (U.S. Food and Drug Administration: Schedule IV Combination). Atropine is purposely added at 25 micrograms per tablet, or ¹/₂₄ to ¹/₄₀ of the usual therapeutic dose for atropine to minimize the potential of misuse by swallowing large numbers of tablets or preparing them for injection since difenoxin is chemically related to the pethidine-piritramide subgroup of the opioid family, and could theoretically be misused. Although unlikely, physical and mental withdrawal symptoms (from both anticholinergic rebound caused by atropine, and opiate withdrawal caused by the difenoxin) is possible if taken for long periods of time. However, both of these compounds are responsible for the medicinal effects of the medicine (both atropine and difenoxin slow gut movement).

This combination medication should not be confused with Lomotil (2.5 mg diphenoxylate and 0.025 mg atropine – a Schedule V Combination), because the active ingredients in the two medications are different compounds, except for the inclusion of atropine. Motofen is approximately 2 to 4 times more effective in treating symptoms than Lomotil.^[1]

Indications and uses

Although Motofen is officially indicated by the U.S. Food and Drug Administration (FDA) for diarrhea, it has also been successfully used by physicians for irritable bowel syndrome (IBS), and hyperhidrosis (chronic, severe sweating).

Side effects, interactions, and misuse potential

Side effects include drowsiness, nausea, vomiting, burning eyes, blurred vision, dry eyes, dizziness, dry mouth, epigastric distress, and constipation (a paradoxical side effect). Side effects attributed to the atropine content (especially when taken in excess doses, or in children), include: flushing, dryness in many areas, urinary retention, insomnia, headache, anxiety, hyperthermia, and tachycardia. It is these side effects that make it undesirable for most patients to take higher amounts of the medicine.

Dosing and administration

The recommended initial dosing is two tablets, and one tablet to be taken after each loose stool thereafter. The therapeutic dosage for Motofen should not exceed 8 tablets (8 milligrams of Difenoxin). There are currently no instructions indicating usage for Irritable Bowel Syndrome (IBS) and Hyperhidrosis, although as stated above, it has been used successfully in treating symptoms of both disorders (which can accompany each other). There was a "Motofen half-strength" tablet, containing only 0.5 milligram of difenoxin, but it has since been discontinued. Only standard 1.0 milligram strength tablets are available by prescription.

Availability, price, and supply

There is currently only one manufacturer of Motofen tablets: Valeant Pharmaceuticals. It acquired the drug from Amarin Pharmaceuticals in 2004^[2]. Valeant's tablets are pentagonal shaped, impressed with a "V" on one side, and vertically scored on the other side. In addition, the number "0500" is impressed bisecting the score line perpendicularly. The aforementioned bisection renders "05" and "00" on the left and right side of the score, respectively. Amarin's version were also pentagonal shaped, but impressed with an "A" on one side with "74" on the opposing.

Motofen is higher priced than both Imodium and Lomotil, does not have a generic equivalent, and is only available by prescription in the United States. Many United States insurance companies do not include Motofen as one of their formulary drugs, causing consumers to pay the highest copay, if it is covered by their health insurance at all. This is most likely due to the high cost of the medication itself, and the fact that similar lower-priced medicines can help ease symptoms of diarrhea. The United States is currently the only country where Motofen tablets are prescribed, approved by the government, and sold.

Miscellaneous information

Strangely, Motofen is only included in the Physicians' Desk Reference (PDR) for the years 2005 and 2006 as a literal snippet entry. Nothing is said about the indications and usage, only the ingredients, current appearance (at the time of publishing), NDC#, and the quantities in which it is supplied. As of August 1, 2008, Motofen appears to have been discontinued by Valeant Pharmaceuticals. No reason has been discovered, and many have been left wondering why it is no longer available.

Motofen is now back on the market as of June 2011 and available only by prescription in the United States.

References

1. ^ Free Patents Online. "Method for management of Diarrhea". Method for Management of Diarrhea. http://www.freepatentsonline.com/WO2007111945.html. Retrieved August 1, 2008. 
2. ^ http://phx.corporate-ir.net/phoenix.zhtml?c=119269&p=irol-newsArticle&ID=498997

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