Coadministration of ~230 ml grapefruit juice and a 400 mg single dose of indinavir to 10 subjects resulted in decreases in indinavir Cmax, AUC and Cmin of 35%, 27% and 10% respectively.
Crixivan Prescribing Information, Merck & Co Inc, May 2018.

Administration of indinavir (800 mg every 8 h for 4 doses) with grapefruit juice or Seville orange juice was studied in 13 healthy volunteers. No statistically significant changes in indinavir pharmacokinetics were observed when indinavir was taken with either fruit juice compared to control (water).
Effect of Seville orange juice and grapefruit juice on indinavir pharmacokinetics in healthy volunteers. Penzak SR, Acosta EP, Turner M et al. J Clin Pharmacol, 2002, 42:1165-1170

The effects of double strength grapefruit juice (180 ml) on the pharmacokinetics of indinavir (800 mg) were studied in 14 HIV+ subjects. Concomitant administration of grapefruit juice was found to increase gastric pH and delay indinavir absorption, but there were no significant differences in indinavir Cmax or AUC compared to values obtained when indinavir was given with water.
Effects of grapefruit juice on pharmacokinetic exposure to indinavir in HIV-positive subjects. Shelton MJ, Wynn HE, Hewitt RG, DiFrancesco R. J Clin Pharmacol, 2001, 41:435-442.