Is there an upper limit for the dose of pyridostigmine (Mestinon) during lactation?
A 34-year-old mother with myasthenia gravis is treated with pyridostigmine 120 mg x4 and 180 mg nocte. This dose is higher than during previous pregnancy and lactation periods. The child was born healthy and was observed for five days in the neonatal department.
The agent increases growth hormone secretion and release through its anticholin-esterase activity, and has been used for study of neuroendocrine control of GH secretion. Long time effects on GH secretion and growth, however, still remain unclear (1).
Pyridostigmine and neostigmine are absorbed poorly after oral administration, and much larger doses are needed than by the parenteral route. A parenteral dose of 0.5-2.0 mg neostigmine equals 15-30 mg or more orally (2).
Pyridostigmine is excreted into breast milk (3,4,5). In two women receiving 120-300 mg/day, milk:plasma ratios were 0.36-1.13 (4). There were no adverse effects noted in the infants, in one infant pyridostigmine could not be identified (detection limit 2 micrg) (4,5). It is estimated that the infant receive 0.05-0.12 per cent of the weight adjusted maternal dosage daily (6,7). The American Academy of Pediatrics considers pyridostigmine to be compatible with breast feeding (3).
Pyridostigmine is almost exclusively eliminated through the kidney in unchanged form (8). Even though the risk for pharmacological effects on the child seems low, the child should be observed for cholinergic adverse effects, having in mind that the renal function not is fully developed (9).
There has been found no reports on adverse effects in the infant during breast feeding. In a recent study of pregnancies of 69 women with myasthenia gravis, nursing data were available for 33 patients. Twenty-five of them were nursing successfully. Nursing is sometimes disrupted to avoid exhausting of the mother, but it must be done cautiously to avoid deterioration of myasthenia gravis (11).
Only small amounts of data excist on the issue of breast feeding during treatment with pyridostigmine. Data on pyridostigmine in breast milk are based on studies with about half the dosage compared to the present case. Only negligible amounts of the drug can be found in the milk and in nursing infants. This ought to be the case also when the dose applied to the mother come close to the maximum recommended for treatment of myasthenia gravis. Therefore breast feeding may be used patients with myasthenia gravis being treated with pyridostigmine.
Bjerring Lauritsen N
Senast ändrad 2018-09-20