No interaction study has been performed. The limited data available from a phase IIa study in HIV-infected patients suggest that no significant interaction is expected between nevirapine and TPV/r. Moreover a study with TPV/r and another NNRTI (efavirenz) did not show any clinically relevant interaction. No dose adjustment is necessary.
Aptivus Summary of Product Characteristics, Boehringer Ingelheim Ltd, July 2020.

Coadministration of nevirapine (200 mg twice daily) and tipranavir/ritonavir (250/200 mg twice daily) to 26 HIV+ subjects resulted in no significant changes in nevirapine Cmax, AUC or Cmin (decreases of 3-4%). When coadministered with tipranavir/ritonavir (750/100 mg) to 22 HIV+ subjects, nevirapine Cmax, AUC and Cmin decreased by 14%, 11% and 7% respectively. When coadministered with tipranavir/ritonavir (1250/100 mg) to 17 HIV+ subjects, nevirapine Cmax, AUC and Cmin decreased by 29%, 24% and 23% respectively.
Aptivus Prescribing Information, Boehringer Ingelheim, June 2020.

No specific drug-drug interaction study has been performed. The limited data available from a phase IIa study in HIV-infected patients have shown a clinically non-significant 20% decrease of tipranavir Cmin. Tipranavir and nevirapine can be coadministered without dose adjustments.
Viramune Summary of Product Characteristics, Boehringer Ingelheim Ltd, November 2019.

No significant interaction was observed when tipranavir was co-administered with low dose ritonavir and nevirapine.
Viramune Prescribing Information, Boehringer Ingelheim Pharmaceuticals Inc, October 2019.

The addition of tipranavir/ritonavir (1250/100 mg, n=17; 750/100 mg, n=22; 250/100 mg, n=26) was studied in HIV+ subjects on stable HAART regimens containing nevirapine. No clinically significant changes in nevirapine Cmin were observed.
Pharmacokinetic drug interaction screen of three doses of tipranavir/ritonavir in HIV-infected patients on stable highly active antiretroviral therapy. Goebel FD, Sabo JP, MacGregor TR, et al. HIV DART, Naples (Florida), December 2002.

Coadministration of tipranavir (1250 mg bd), ritonavir (200 mg bd oral solution) and nevirapine (200 mg bd) was studied in 4 subjects. There was no significant effect of nevirapine on the pharmacokinetics of tipranavir (decreases of 15%, 19% and 3% for AUC, Cmax and Cmin respectively). Tipranavir/ritonavir resulted in non-significant decreases in nevirapine AUC, Cmax and Cmin of 20%, 25% and 14% respectively. Tipranavir appeared to increase the total clearance of ritonavir by ~6.5-fold (compared to historical data) and when nevirapine was included, a further 62% increase in total clearance of ritonavir was observed.
Pharmacokinetics of tipranavir and nevirapine. Sabo J, MacGregor T, Lamson M, et al. 10th Annual Canadian Conference on HIV/AIDS Research, Toronto, June 2001, abstract 249P.