Coadministration of darunavir/ritonavir and maraviroc (150 mg twice daily) increased maraviroc AUC and Cmax by 305% and 129%, respectively. Darunavir and ritonavir concentrations were consistent with historical data. The maraviroc dose should be 150 mg twice daily when coadministered with darunavir with low dose ritonavir.
Prezista Summary of Product Characteristics, Janssen-Cilag Ltd, June 2012.

Coadministration of maraviroc (150 mg twice daily) and darunavir/ritonavir (600/100 mg twice daily) was studied in 12 subjects. AUC, Cmax and Cmin of maraviroc increased by 4.05-, 2.29-, and 8.00-fold, respectively. When maraviroc (150 mg twice daily) and darunavir/ritonavir (600/100 mg twice daily) were coadministered in the presence of etravirine (n=10), maraviroc AUC, Cmax and Cmin increased by 3.10-, 1.77-, and 5.27-fold, respectively. Maraviroc concentrations are increased when coadministered with darunavir/ritonavir. When used in combination with darunavir/ritonavir, the dose of maraviroc should be 150 mg twice daily.
Prezista Prescribing Information, Tibotec Inc, June 2012.

Maraviroc dose should be decreased to 150 mg twice daily when co-administered with a PI other than tipranavir/ritonavir (coadministration with fosamprenavir/ritonavir is not recommended). Coadministration of darunavir/ritonavir (600/100 mg twice daily) and maraviroc (150 mg twice daily) increased maraviroc AUC by 4.05-fold and Cmax by 2.29-fold. Darunavir/ritonavir concentrations were consistent with historical data. When given with darunavir/ritonavir to patients with impaired renal function (creatinine clearance <80 ml/min), maraviroc should be reduced to 150 mg every 24 h.
Celsentri Summary of Product Characteristics, ViiV Healthcare, October 2013.

Coadministration of darunavir/ritonavir (600/100 mg twice daily) and maraviroc (150 mg twice daily) to 12 subjects increased maraviroc AUC, Cmax and Cmin by 4.05-fold, 2.29-fold and 8.00-fold, respectively. Coadministration is not recommended in patients with creatinine clearance <30 ml/min or on haemodialysis.
Selzentry Prescribing Information, ViiV Healthcare, September 2013.

The effect of darunavir/ritonavir (600/100 mg twice daily) on the pharmacokinetics of maraviroc (150 mg twice daily) was investigated in 12 HIV- subjects. The AUC and Cmax of maraviroc were increased by 4-fold and 2.3-fold, respectively in the presence of darunavir/ritonavir. Pharmacokinetic parameters for darunavir and ritonavir were similar to historical data. Maraviroc dose should be decreased to 150 mg twice daily when coadministered with darunavir/ritonavir.
An open, randomised, 2-way crossover study to investigate the effect of darunavir/ritonavir on the pharmacokinetics of maraviroc in healthy subjects. Abel S, et al. 8th International Workshop on Clinical Pharmacology of HIV Therapy, Budapest, April 2007, abstract 55.

PIs + Efavirenz
Maraviroc dose should be decreased to 150 mg twice daily when co-administered with efavirenz in the PRESENCE of a PI (other than tipranavir/ritonavir where the dose should be 600 mg twice daily). Efavirenz and darunavir/ritonavir has not been studied. Based on the extent of inhibition by darunavir/ritonavir in the absence of efavirenz, an increased exposure is expected. 
Celsentri Summary of Product Characteristics, ViiV Healthcare, October 2013.