Recommendations for Use of Antiretroviral Drugs in Pregnant HIV-1-Infected Women for Maternal Health and Interventions to Reduce Perinatal HIV Transmission in the United States
Nucleoside and Nucleotide Analogue Reverse Transcriptase Inhibitors
Lamivudine (Epivir, 3TC)
(Last updated:7/31/2012; last reviewed:7/31/2012)
Lamivudine (Epivir, 3TC) is classified as FDA Pregnancy Category C.
Animal carcinogenicity studies
Lamivudine has weak mutagenic activity in one in vitro assay but no evidence of in vivo genotoxicity in rats at 35 to 45 times human exposure. Long-term animal carcinogenicity screening studies at 10 and 58 times human exposure have been negative in mice and rats, respectively.
Reproduction/fertility
Lamivudine administered to rats at doses up to 4000 mg/kg/day, producing plasma levels 47 to 70 times those in humans, revealed no evidence of impaired fertility and no effect on the offsprings’ survival, growth, and development up to the time of weaning.
Teratogenicity/developmental toxicity studies
There is no evidence of lamivudine-induced teratogenicity at 35 times human plasma levels in rats and rabbits. Early embryolethality was seen in rabbits at doses similar to human therapeutic exposure but not in rats at 35 times the human exposure level.
In the Antiretroviral Pregnancy Registry, sufficient numbers of first-trimester exposures to lamivudine in humans have been monitored to detect at least a 1.5-fold increase in risk of overall birth defects and a 2-fold increase in the most commonly occurring birth defects, such as defects of the cardiovascular and genitourinary systems. No such increase in birth defects has been observed with lamivudine. Among cases of first-trimester lamivudine exposure reported to the Antiretroviral Pregnancy Registry, the prevalence of birth defects was 3.1% (127 of 4,088 births; 95% CI, 2.6%–3.7%) compared with a 2.7% total prevalence in the U.S. population, based on CDC surveillance.1
Placental and breast milk passage
Lamivudine readily crosses the placenta in humans, achieving comparable cord blood and maternal concentrations.2 In a study of 123 mother/infant pairs, the placental transfer expressed as fetal-to-maternal AUC ratio was 0.86, and the lamivudine amniotic fluid accumulation, expressed as the amniotic fluid-to-fetal AUC ratio, was 2.9.3 Other studies have also noted amniotic fluid accumulation of lamivudine.4 This is likely secondary to renal excretion of lamivudine by the fetus; lamivudine diffuses from maternal to fetal blood through the placenta and the fetal kidney removes lamivudine from fetal blood and concentrates it in urine, with fetal micturition causing a rise in the concentration of lamivudine in amniotic fluid.
Lamivudine is excreted into human breast milk. In a study in Kenya of 67 HIV-infected nursing mothers receiving a combination regimen of zidovudine, lamivudine, and nevirapine, the median breast milk lamivudine concentration was 1214 ng/mL and the median ratio of lamivudine concentration in breast milk to that in plasma was 2.56.5 In infants who received lamivudine only via breast milk, median plasma lamivudine concentration was 23 ng/mL (half-maximal IC50 of wild-type HIV against lamivudine = 0.6–21 ng/mL).
Human studies in pregnancy
Two studies have evaluated lamivudine PKs in HIV-infected pregnant women, one evaluating drug levels in 57 mother/infant pairs on the day of delivery 4 and the other evaluating PKs in 20 women starting lamivudine/zidovudine at 38 weeks gestation.2 These studies concluded that there was a lack of effect of pregnancy on lamivudine PKs after 38 weeks of pregnancy. In a larger study of 114 pregnant women, 123 women in labor, and 47 non-pregnant women receiving a lamivudine-containing regimen who had samples collected for therapeutic drug monitoring (given as 150 mg twice daily with zidovudine or 300 mg once daily with abacavir), data were retrospectively analyzed using a population PK approach.3 Pregnant women had a 22% higher apparent clearance than non-pregnant and postpartum women, but this increase did not lead to subtherapeutic exposure; the level of lamivudine exposure in pregnant women, although lower than exposure in non-pregnant and parturient women, was relatively close to data reported previously for non-pregnant adults. Thus, no dose adjustment in pregnancy is necessary.
References
- Antiretroviral Pregnancy Registry Steering Committee. Antiretroviral pregnancy registry international interim report for 1 Jan 1989 - 31 January 2012. Wilmington, NC: Registry Coordinating Center; 2012. Available at http://www.APRegistry.com.
- Moodley J, Moodley D, Pillay K, et al. Pharmacokinetics and antiretroviral activity of lamivudine alone or when coadministered with zidovudine in human immunodeficiency virus type 1-infected pregnant women and their offspring. J Infect Dis. Nov 1998;178(5):1327-1333. Available at http://www.ncbi.nlm.nih.gov/pubmed/9780252.
- Benaboud S, Treluyer JM, Urien S, et al. Pregnancy-related effects on lamivudine pharmacokinetics in a population study with 228 women. Antimicrob Agents Chemother. Feb 2012;56(2):776-782. Available at http://www.ncbi.nlm.nih.gov/pubmed/22106227.
- Mandelbrot L, Peytavin G, Firtion G, Farinotti R. Maternal-fetal transfer and amniotic fluid accumulation of lamivudine in human immunodeficiency virus-infected pregnant women. Am J Obstet Gynecol. Jan 2001;184(2):153-158. Available at http://www.ncbi.nlm.nih.gov/pubmed/11174495.
- Mirochnick M, Thomas T, Capparelli E, et al. Antiretroviral concentrations in breast-feeding infants of mothers receiving highly active antiretroviral therapy. Antimicrob Agents Chemother. Mar 2009;53(3):1170-1176. Available at http://www.ncbi.nlm.nih.gov/pubmed/19114673.