Updates-By Carol A. Kemper, MD, FACP
Updates-By Carol A. Kemper, MD, FACP
Once-Daily ddI No More
Source: Product information, Bristol-Myers Squibb Company, August 1, 2000. Molina JM, et al. 38th Annual Mtg of IDSA, September 7-10, 2000.
Armed with pharmacokinetic data and hoping that further simplification of antiretroviral therapy would improve adherence and tolerability, many HIV practitioners leapt onto the band wagon last year and began prescribing didanosine (ddI) once daily. Unfortunately, preliminary data from a recently completed Bristol-Myers Squibb open-label study (AI454-148) indicate that treatment-naïve patients receiving ddI once daily in combination with stavudine (d4T) and nelfinavir (NLF) were less likely to have undetectable viral loads at 48 weeks of therapy than the comparator arm of the study.
Unfortunately, the comparison leaves something to be desired. Patients in the alternate arm received a combination of zidovudine (AZT), lamivudine (3TC), and NLF, and did not receive ddI. However, a statistically significant difference between the ddI/d4T/NLF vs. AZT/3TC/NLF regimens in the proportion of patients with HIV RNA less than 400 copies/mL was detected at 48 weeks (50% vs 59%). Similarly, significantly fewer patients receiving the once-daily ddI-containing regimen had HIV RNA less than 50 copies/mL at 48 weeks compared with the non-ddI-containing arm (34% vs 47%). No data on the tolerance of the respective regimens was available, although this is likely to be a significant factor in the successful response to a ddI-containing regimen. On the other hand, a late-breaker report by French Investigators at the 38th Annual Meeting of the Infectious Diseases Society of America (IDSA) found that a once-daily triple combination regimen containing ddI was very successful in maintaining viral suppression up to 48 weeks.
Forty patients received a combination of emtricitabine, a new investigational nucleoside reverse transcriptase inhibitor (Conviracil, Triangle Pharmaceuticals, Inc.), plus ddI 250 to 400 mg (depending on weight) and efavirenz 600 mg once daily. At 24 weeks, 39 or 40 patients (98%) had viral loads less than 400 copies/mL, and 34 (93%) were less than 50 copies/mL. Durable suppression was at 48 weeks with 95% of the patients maintaining viral loads less than 400 copies/mL. Only two (5%) patients discontinued their regimen because of adverse events.
This data suggests that a once daily combination regimen for HIV-containing ddI can be very effective. Nevertheless, the packaging information for ddI has been updated to reflect the newer information. Twice-daily ddI dosing is formally recommended for all patients, except those whose management requires a once-daily dosing schedule.
Can Dandruff Shampoos Kill Yeast?
Source: Bulmer AC, Bulmer GS. Mycopathologia 2000;147:63-65.
The yeast, Malassezia furfur, is generally believed to play a pathogenic role in the development of that chronic scalp condition called seborreic dermatosis—or dandruff—although it may simply be a normal human commensal in others. Bulmer and Bulmer examined the antifungal activity of six different over-the-counter hair shampoos purported to be helpful in the treatment of dandruff, including Head & Shoulders (Janssen), Pantene Blue (Proctor & Gamble), Gard Violet (Colgate-Palmolive), Selsun Blue (Abbott), and Nizoral 1%, and Nizoral 2% (both Janssen). Serial 10-fold dilutions (up to 106) of the shampoo products were tested for their antifungal activity against plates of cultured M. furfur, isolated from the scalp of a single individual with dandruff.
All of the products demonstrated some antifungal activity at dilutions of as little as 1:1000. Not surprisingly, however, the Nizoral shampoos, containing ketozonazole, were consistently more active than the other products. The 2% Nizoral shampoo was 10 times more active than the 1% product, and both were at least 100 times better than any of the other products. Whether this translates into a more effective product at controlling dandruff is unknown, but in the absence of any better clinical data, I’d choose the Nizoral products if I had a problem.
Hematogenous Transmission of BSE
Source: Houston F, et al. Lancet 2000; 356:999-1000.
Ingesting beef infected with new variant Creutzfeldt-Jacob disease (nvCJD) has been linked to the development in humans of bovine spongiform encephalopathy (BSE), or "mad cow disease." A subject of greater debate is the transmissibility of this new mutant prion strain via blood products. Hedging its bets, Britain established a policy two years ago stipulating the removal of white blood cells from all blood products.
Houston and colleagues in Edinburgh fed 5 grams of BSE-affected cattle brain to 19 UK Cheviot sheep. Before any symptoms became apparent in the sheep, samples of their blood were transfused into a healthy scrapie-free flock of sheep imported from New Zealand. Although some of the flock had only recently been transfused, one of the transfused sheep began to show signs of illness after 610 days. Widespread prion-protein deposition was demonstrated throughout the animal’s brain and peripheral tissues.
Although lacking in any controlled data, this finding suggests that the human form of BSE may be transmissible via blood products, even in advance of apparent symptoms in the donor. Because no cases of humans becoming infected from a blood transfusion have been documented, scientists cautioned that the risk remains theoretical. The Health Service in Britain suggested that this preliminary data did not indicate any new risk to the public.
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