LINCOMYCIN

Fetal Risk Summary

No reports linking the use of lincomycin with congenital defects have been located. The antibiotic crosses the placenta, achieving cord serum levels about 25% of the maternal serum level (1,2). Multiple IM injections of 600 mg did not result in accumulation in the amniotic fluid (2). No effects on the newborn were observed.

The progeny of 302 patients treated at various stages of pregnancy with oral lincomycin, 2 g/day for 7 days, were evaluated at various intervals up to 7 years after birth (3). As compared with a control group, no increases in malformations or in delayed developmental defects were observed.

Breast Feeding Summary

Lincomycin is excreted into breast milk. Six hours following oral dosing of 500 mg every 6 hours for 3 days, serum and milk levels in nine patients averaged 1.37 and 1.28 µg/mL, respectively, a milk:plasma ratio of 0.9 (1). Much lower milk:plasma ratios of 0.13–0.17 have also been reported (4). Although no adverse effects have been reported, three potential problems exist for the nursing infant: modification of bowel flora, direct effects on the infant, and interference with the interpretation of culture results if a fever workup is required.

References

1. Medina A, Fiske N, Hjelt-Harvey I, Brown CD, Prigot A. Absorption, diffusion, and excretion of a new antibiotic, lincomycin. Antimicrob Agents Chemother 1963;189–96.
2. Duignan NM, Andrews J, Williams JD. Pharmacological studies with lincomycin in late pregnancy. Br Med J 1973;3:75–8.
3. Mickal A, Panzer JD. The safety of lincomycin in pregnancy. Am J Obstet Gynecol 1975;121:1071–4.
4. Wilson JT. Milk/plasma ratios and contraindicated drugs. In Wilson JT, ed. Drugs in Breast Milk. Balgowlah, Australia:ADIS Press, 1981:78–9.