Mestinon (Pyridostigmine bromide) Central nervous system agents Muscle relaxants adjuncts to anesthesia Reversal of the effects of non-depolarizing drugs, curariform antagonist, Myasthenia Gravis (disease that causes muscle weakness). (Adults) Average 10 tablets/day, spaced to provide maximum relief. Dose requirements range from 1 tablet to 25 tablets. Category NR. Muscle Cramps, weakness, nausea, vomiting, Diarrhea, abdominal cramps, Bradycardia miosis, muscle fasciculations, bronchospasm, diaphoresis. Pregnancy Risk Categories defined: A: Studies in pregnant women failed to show a risk to the fetus in the first trimester - with no evidence of risk in the later trimesters. B: Animals studies indicate no adverse effect to the fetus, but there are no adequate, clinical studies in pregnant women. C: Animal studies have shown an adverse effect on the fetus, but there are no adequate, clinical studies in humans. Despite potential risks, the drug may be useful in pregnant women. D: There is evidence of risk to the human fetus, but the potential benefits of use in pregnant women may be acceptable, despite potential risks. X: Studies in animals or humans show fetal abnormalities, or adverse reaction reports indicate evidence of fetal risk. Warning: the risks involved clearly outweigh any potential benefit from using the drug in pregnant women, regardless of trimester. NR: Not rated (i.e., no information available at this time as to the potential risks or benefits).