Protease Inhibitors  NEW!

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Effects of Protease Inhibitors and Other Commonly Used Medications as Determined by Drug Interaction Studies
*Dosage Adjustments should be determined by a physician*

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Drug Category: ANTIMYCOBACTERIALS
Drug Name	Invirase™ Roche saquinavir	Recommend	Norvir™ Abbott ritonavir	Recommend	Crixivan® Merck indinavir	Recommend
Clarithromycin (Biaxin)	no studies have been conducted - no data available		clarithromycin AUC increased by 77%	dosage adjustment to patient with renal impariment is necessary	increased indinavir AUC by 29% +/- 42% and increased clarithromycin AUC by 53% +/- 36%	no dosage adjustment necessary
Rifabutin (Mycobutin)	rifabutin decreased saquinavir levels by 40%	if rifabutin therapy is warranted, consider alternative drugs	rifabutin AUC increased by 4 fold rifabutin metabolite (25-0-desacetyl) AUC increased by 35 fold	coadministration of ritonavir and rifabutin is contraindicated	rifabutin AUC increased by 204 +/-142%	reduce rifabutin to half the standard dose
Rifampin (Rifadin, others)	rifampin decreased saquinavir levels by 80%	rifampin and saquinavir should not be administered concomitantly	rifampin decreased ritonavir levels by 35%	no dosage adjustment necessary	rifampin decreased AUC of saquinavir by approximately 80%	rifampin and indinavir should not be administered concomitantly

Drug Category: ORAL CONTRACEPTIVES
Invirase™ Roche saquinavir	Recommend	Norvir™ Abbott ritonavir	Recommend	Crixivan® Merck indinavir	Recommend
no studies have been conducted - no data available		ethinyl estradiol AUC decreased by 40%	dosage increase or alternate contraceptive measures should be considered	Ortho-Novum 1/35 increased ethinyl estradiol 24+/-17% and norethindrone by 26 +/-14%	no dosage adjustment necessary

Drug Category: OTHER
Invirase™ Roche saquinavir	Recommend	Norvir™ Abbott ritonavir	Recommend	Crixivan® Merck indinavir	Recommend
ritonavir markedly increased saquinavir plasma levels (see ritonavir)	safety of this interaction has not been established	desipramine (Norpramin, others) AUC increased by 145% greater than 20-fold increase in saquinavir AUC theophylline (Theo-Dur, others) AUC decreased by 43% tobacco decreased ritonavir AUC by 18%	dosage reduction should be considered safety of this interaction has not been established dosage increase may be required	grapefruit juice decreased indinavir levels by 26%

AUC (Area under the Curve) is a measurement of plasma concentration over time.
qd - every day
tid- three times a day
q8h - every eight hours