Ask the Pharmacist: Mestinon Stomach Issues

Dear Doc,
I take Mestinon every four hours and it helps my MG but it destroys my stomach. Any recommendations? I don’t want to take anything that will interfere with the Mestinon or that will exacerbate my MG. Are over the counter drug a possibility?

Mestinon is a cholinesterase inhibitor that is used to prevent acetylcholine breakdown which allows accumulation of acetylcholine for higher transmission of nerve impulses across neuromuscular junctions. Typically patients tend to experience diarrhea, nausea and abdominal cramps when they are initiated on Mestinon. Side effects will usually resolve over time as long as you are very compliant with your dosing protocol. If you tend to have gastrointestinal (GI) side effects that persist, many physicians will prescribe propantheline (Pro-Banthine) along with Mestinon to counter the side effects. Propantheline is an anticholinergic agent which works on the muscarinic receptors of the GI tract that reduce GI spasms by relaxing the smooth muscle in your gut. Even though it is an anticholinergic agent, do not be concerned because the low doses prescribed by your physician do not affect the nicotinic receptors which are involved in muscle contraction. As for over the counter drugs, (OTC) loperamide (Imodium) is considered a safe medication for controlling diarrhea. Other OTC’s to consider would be an H-2 Blocker such as ranitidine (Zantac) or famotidine (Pepcid) and the following Proton Pump Inhibitor omeprazole (Prevacid OTC). Even though H-2 blockers and PPI’s are used more traditionally for treatment of reflux, stomach ulcers and heartburn there may be some beneficial effects for short term use.


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