HIV and ID Observations

It’s not on Abbott’s web site yet (update:  now it’s here), but the FDA has approved a new formulation of ritonavir — a heat-stable 100 mg tablet.  From an e-mail release by the FDA:

On February 10, 2010, FDA approved Norvir (ritonavir) 100 mg Tablets. These tablets do not require refrigeration.  Unlike the capsule formulation [pictured], Norvir tablets must be taken with meals.
–snip–
NORVIR tablets are not bioequivalent to NORVIR capsules. Under moderate fat conditions (857 kcal; 31% fat, 13% protein, 56% carbohydrates), when a single 100 mg NORVIR dose was administered as a tablet compared with a capsule, AUC_{(0- ∞)} met equivalence criteria but mean C_max was increased by 26% (92.8% confidence intervals: ↑15 -↑39%).

This is obviously an advance — the Norvir soft-gel capsule is much-despised for a variety of reasons, one of the most notable being the glob of melted capsules that results if the medication is left in the car, in a warm room in the summertime, near a radiator, etc.  When Kaletra switched from capsule to tablet, the heat-stability was a big improvement in convenience, and also made treatment in resource-limited settings much easier.

Time will tell if the increase in peak levels has any effect on tolerability, a potential concern since much of ritonavir’s toxicity is dose-related.   I suspect Abbott will have both formulations available for a while until this is sorted out.

And for those who still have patients still on 600 mg twice-daily — it’s time to switch to something else!