Coadministration of nevirapine and zidovudine (100-200 mg three times daily) decreased zidovudine AUC and Cmax by 28% and 30%, respectively. Zidovudine had no effect nevirapine pharmacokinetics. Zidovudine and nevirapine can be co-administered without dose adjustments. Granulocytopenia is commonly associated with zidovudine. Therefore, patients who receive nevirapine and zidovudine concomitantly and especially paediatric patients and patients who receive higher zidovudine doses or patients with poor bone marrow reserve, in particular those with advanced HIV disease, have an increased risk of granulocytopenia. In such patients haematological parameters should be carefully monitored.
Viramune Summary of Product Characteristics, Boehringer Ingelheim Ltd, November 2019.

Coadministration of nevirapine (200 mg once daily for 2 weeks then 200 mg twice daily for 2 weeks) with zidovudine (100-200 mg three times daily) in 11 patients caused a 28% and 30% decrease in zidovudine AUC and Cmax, respectively. Zidovudine Cmin was below the limit of detection for the assay. The effect on nevirapine pharmacokinetics was not significant when compared to historical controls.
Viramune Prescribing Information, Boehringer Ingelheim Pharmaceuticals Inc, October 2019.

Addition of nevirapine (200 mg twice daily) to a regimen of zidovudine (200 mg three times daily) and didanosine in 80 HIV+ individuals showed nevirapine reduced the bioavailability of ZDV by ~30%. The interaction is unlikely to be clinically significant, but could have an impact on the selection of resistant mutants. Zidovudine had no effect on the pharmacokinetics of nevirapine. No dosage adjustments are required.
Population pharmacokinetics of nevirapine, zidovudine and didanosine in human immunodeficiency virus-infected patients. Zhou XJ, Sheiner LB, D'Aquila RT et al. Antimicrob Agents Chemother, 1999, 43:121–8.