Drug interactions

Since tipranavir (Aptivus) inhibits the CYP3A enzyme when it is boosted with ritonavir, patients taking it should not take the following drugs, due to dangerous interactions:

  • Alfuzosin
  • Amiodarone (Cordarone X), due to heart problems
  • Astemizole, due to heart problems
  • Atorvastatin (Lipitor), due to increased atorvastatin levels and an increased risk of side-effects
  • Bepridil, due to heart problems
  • Cisapride, due to heart problems
  • Colchicine in patients with renal or hepatic impairment
  • Ergotamine tartrate (Cafergot / Migril), due to heart problems
  • Flecainide acetate (Tambocor), due to heart problems
  • Halofantrine
  • Hypericin (St John’s wort), due to decreased tipranavir levels
  • Lovastatin, due to the risk of lovastatin-associated side-effects
  • Lumefantrine
  • Midazolam (Hypnovel, Versad), due to the risk of sedation or breathing problems. Oral therapy is counterindicated and parenteral therapy should be closely monitored
  • Pimozide (Orap), due to heart problems
  • Propafenone, due to heart problems
  • Quinidine sulphate (Kinidin Dureles), due to heart problems
  • Rifampicin (Rifadin / Rimactane), due to an 80% reduction in tipranavir levels
  • Simvastatin (Zocor), due to simvastatin-associated side-effects
  • Terfenadine, due to heart problems
  • Triazolam, due to the risk of sedation or breathing problems.

Tipranavir has been reported to reduce levels of saquinavir (Invirase), amprenavir (Agenerase) and lopinavir, despite the presence of ritonavir (Norvir) as a boosting agent in the drug combination.1 At present Boehringer Ingelheim cannot advise on the dose adjustments that would be necessary if tipranavir is used alongside one of these protease inhibitors because it needs to carry out further research. Therapeutic drug monitoring is likely to be the only way of determining whether adjusted doses are achieving adequate concentrations of protease inhibitors used alongside tipranavir.

Data collected from four drug interaction studies of tipranavir in HIV-negative people found that standard doses of AZT (zidovudine, Retrovir), tenofovir (Viread), ddI (didanosine, Videx / VidexEC) and efavirenz may be used with ritonavir-boosted tipranavir.2 Total exposure to AZT is reduced by 33 to 43% when taken with tipranavir but Boehringer Ingelheim has not recommended dose adjustments at this stage. However, enteric-coated ddI should be taken at least hours apart from tipranavir, due to decreases in ddI levels if it is taken with food.

Sildenafil is contraindicated if used for treatment of pulmonary arterial hypertension.

Other interaction studies involving tipranavir have reported that antacids reduce the blood levels of tipranavir by one third.3 Tipranavir may also reduce the efficacy of oestrogen-based hormonal contraceptives. Additional forms of contraception should be used.

Additional drug interaction studies are planned.

References

  1. Walmsley S et al. Pharmacokinetics and safety of tipranavir / ritonavir (TPV / r) alone or in combination with saquinavir (SQV), amprenavir (APV), or lopinavir (LPV): Interim analysis of BI1182.51. 15th International AIDS Conference, Bangkok, abstract WeOrB1236, 2004
  2. Roszko PJ et al. Standard doses of efavirenz, zidovudine, tenofovir, and didanosine may be given with tipranavir / ritonavir. Second International AIDS Society Conference, Paris, abstract 865, 2003
  3. Baldwin JR et al. Effects of food and antacid on bioavailability of the protease inhibitor PNU-140690 in healthy volunteers. Fifth Conference on Retroviruses and Opportunistic Infections, Chicago, abstract 649, 1998
Community Consensus Statement on Access to HIV Treatment and its Use for Prevention

Together, we can make it happen

We can end HIV soon if people have equal access to HIV drugs as treatment and as PrEP, and have free choice over whether to take them.

Launched today, the Community Consensus Statement is a basic set of principles aimed at making sure that happens.

The Community Consensus Statement is a joint initiative of AVAC, EATG, MSMGF, GNP+, HIV i-Base, the International HIV/AIDS Alliance, ITPC and NAM/aidsmap
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This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.

NAM’s information is intended to support, rather than replace, consultation with a healthcare professional. Talk to your doctor or another member of your healthcare team for advice tailored to your situation.