MECAMYLAMINE

Fetal Risk Summary

Mecamylamine, a secondary amine, is a potent antihypertensive and ganglionic blocker that is indicated for the management of moderately severe to severe essential hypertension and uncomplicated cases of malignant hypertension (1,2). The antihypertensive effect is predominantly orthostatic, but supine blood pressure is also significantly reduced.

Although the manufacturers state that animal reproduction studies have not been conducted (1,2), a 1998 study observed no teratogenicity in pregnant rat and rabbit experiments (3).

Mecamylamine crosses the human placenta to the fetus (1,2). This is consistent with its relatively low molecular weight (about 204 for the hydrochloride salt).

Except for a single case included with other antihypertensives in the data of the Collaborative Perinatal Project (4), no reports on the use of mecamylamine during human pregnancy have been located. The near absence of human and animal reproduction data prevents an assessment of the fetal risk. However, lowering of maternal hypertension may compromise the placental perfusion, resulting in fetal hypoxia (as indicated by bradycardia) and death.

Breast Feeding Summary

No reports describing the use of mecamylamine in human lactation have been located. The low molecular weight (about 204 for the hydrochloride salt) suggests that the drug is excreted into breast milk. The effect of this exposure on a nursing infant is unknown.

References

1. Product information. Inversine. Layton Bioscience, 2001.
2. Product information. Inversine. Merck, 2001.
3. Schroeder RE, Betlach CJ. Subcutaneous developmental toxicity studies in rats and rabbits with nicotine and mecamylamine in combination. Toxicologist 1998;42:257. As cited by Schardein JL. Chemically Induced Birth Defects. 3rd ed. New York, NY: Marcel Dekker, 2000:527.
4. Heinonen OP, Slone D, Shapiro S. Birth Defects and Drugs in Pregnancy. Littleton, MA: Publishing Sciences Group, 1977:372.