Paxlovid Use In Pregnancy & Lactation

Women of childbearing potential/Contraception in males and females: There are limited human data on the use of Paxlovid during pregnancy to inform the drug-associated risk of adverse developmental outcomes, women of childbearing potential should avoid becoming pregnant during treatment with Paxlovid.
Use of ritonavir may reduce the efficacy of combined hormonal contraceptives. Patients using combined hormonal contraceptives should be advised to use an effective alternative contraceptive method or an additional barrier method of contraception during treatment and until after one complete menstrual cycle after stopping Paxlovid (see Interactions).
Pregnancy: There are limited data from the use of Paxlovid in pregnant women. Paxlovid should be used during pregnancy only if the potential benefits outweigh the potential risks for the mother and the foetus.
Animal data with nirmatrelvir have shown developmental toxicity in the rabbit (lower foetal bodyweights) but not in the rat. There was no nirmatrelvir-related effect on foetal morphology or embryo-foetal viability at any dose tested in rat or rabbit embryo-foetal developmental toxicity studies. There were no nirmatrelvir-related adverse effects in a pre- and postnatal developmental study in rats (see Pharmacology: Toxicology: Preclinical safety data under Actions).
A large number (6100 live births) of pregnant women were exposed to ritonavir during pregnancy; of these, 2800 live births were exposed during the first trimester. These data largely refer to exposures where ritonavir was used in combination therapy and not at therapeutic ritonavir doses but at lower doses as a pharmacokinetic enhancer for other protease inhibitors, similar to the ritonavir dose used for nirmatrelvir/ritonavir. These data indicate no increase in the rate of birth defects compared to rates observed in population-based birth defect surveillance systems. Animal data with ritonavir have shown reproductive toxicity (see Pharmacology: Toxicology: Preclinical safety data under Actions).
Breast-feeding: In a clinical pharmacokinetics study, 8 healthy lactating women who were at least 12 weeks postpartum were administered 3 doses (steady-state dosing) of 300 mg/100 mg nirmatrelvir/ritonavir. Nirmatrelvir and ritonavir were excreted in breastmilk in small amounts, with a milk to plasma AUC ratio of 0.26 and 0.07, respectively. The mean (range) estimated daily infant dose (assuming average milkconsumption of 150 mL/kg/day), was 1.8% (1.3-2.5%) and 0.2% (0.1-0.3%) of the maternal dose.
There are no available data on the effects of nirmatrelvir or ritonavir on the breast-fed newborn/infant or on milk production. A risk to the newborn/infant cannot be excluded. Breast-feeding should be discontinued during treatment with Paxlovid and for 48 hours after the last dose of Paxlovid.
Fertility: There are no human data on the effect of Paxlovid on fertility. No human data on the effect of nirmatrelvir on fertility are available. Nirmatrelvir produced no effects on fertility in rats (see Pharmacology: Toxicology: Preclinical safety data under Actions).
There are no human data on the effect of ritonavir on fertility. Ritonavir produced no effects on fertility in rats.