Pharmacology Watch: Valacyclovir Reduces Genital Herpes Transmission
February 1, 2004 6 minutes read
Valacyclovir Reduces Genital Herpes Transmission
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A once-a-day dose of a valacyclovir reduces the rate of transmission of genital herpes (HSV-2) from an infected partner to an uninfected susceptible partner, according to a new study. The study group included 1484 immunocompetent, heterosexual, monogamous couples in which 1 partner had symptomatic genital HSV-2 and the other was susceptible to HSV-2. The infected partners were randomized to valacyclovir 500 mg once daily or placebo for 8 months. At the end of the study period, clinically symptomatic HSV-2 infections developed in 4 of 743 susceptible partners in the valacyclovir group vs 16 of 741 in the placebo group (HR, 0.25; 95% CI, 0.08-0.75; P = 0.008). Overall acquisition of HSV-2, including asymptomatic infections, was observed in 14 partners in the valacyclovir group compared to 27 in the placebo group (HR, 0.52; 95% CI, 0.27-0.99; P = 0.04). Valacyclovir significantly cut down on viral shedding in the infected partner and also significantly cut down on the rate of HSV-2 outbreaks in the infected partner. The authors caution that 37% of couples in the study did not use condoms even though counseled to do so, and that condom use and abstinence during attacks are the most effective methods of preventing transmission (N Engl J Med. 2004;350:11-20).
Erythropoietin Safe for Cancer Patients?
A fascinating news item published in the December 17 issue of Journal of the National Cancer Institute raises the question of whether erythropoietin is safe to use in cancer patients. According to the news report, several studies suggest that many cancer cells have erythropoietin receptors that may be stimulated by erythropoietin injections. Erythropoietin is commonly given to cancer patients to treat chemotherapy-related, or cancer-related anemia. Two recent trials have shown that erythropoietin use is associated with decreased survival in some cancer patients according to the news report. Erythropoietin receptors have been found on head and neck cancer cells, prostate cancer cells, and ovarian cancer cells, as well as breast, renal, and uterine cancer cells. Preliminary data suggest that some of these cancers may actually proliferate in the presence of erythropoietin. The association between erythropoietin and decreased survival for some cancer patients needs further evaluation (J Natl Cancer Inst. 2003;95:1820-1821).
WHI, ALLHAT Trials Still Spur Research
It appears that 2 landmark studies have significantly changed practice patterns in this country. The Women’s Health Initiative (WHI) study published in July 2002, and the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) published in April 2000 both showed negative results with some of the most widely prescribed pharmaceuticals in this country. WHI suggested that combined estrogen/progesterone increases the risk of breast cancer and cardiovascular disease in postmenopausal women. Researchers from Stanford looked at prescription trends in hormone therapy from 1995 to July 2003. Annual hormone therapy prescriptions increased dramatically between 1995 in 1999 and then remained stable through June 2002. Following publication of the WHI in July 2002, prescriptions for Prempro, the combination estrogen/progesterone used in the study, declined by 56%. New prescriptions for conjugated estrogen also declined significantly. Small increases were seen with topical estrogens and low-dose estrogen preparations over the same time period (JAMA. 2004;291:47-53). ALLHAT was terminated early and the results released in December 1999, and published in April 2000 because early results showed that doxazosin, an alpha-blocker, was significantly inferior to diuretics with respect to preventing stroke, congestive heart failure, and a composite of other cardiovascular outcomes. The same group from Stanford reviewed alpha-blocker prescription trends from 1996 to 2002. Steady increases in alpha-blocker prescriptions were seen in between 1996 and 1999, but new prescriptions for the drugs declined 26% between 1999 and 2002. Changes in pricing, generic version, drug promotion, or competition did not have a confounding effect. The authors conclude that modest declines in alpha-blocker prescribing were seen after publication of ALLHAT (JAMA. 2004;291:54-62).
Alpha-Blockers Useful in BPH Treatment
Alpha-blockers are useful in treatment with benign prostatic hyperplasia (BPH). Now a new study shows that the combination of the 5-alpha-reductase inhibitor finasteride (Proscar) with an alpha-blocker may be superior to either drug alone in treating BPH. Researchers randomized 3047 men to placebo, doxazosin, finasteride, or combination therapy with the end point of clinical progression of BPH. Clinical progression was defined as an increase in the American Urologic Association symptom score of these 4 points, acute urinary retention, urinary incontinence, renal insufficiency, or recurrent urinary tract infection. Both doxazosin and finasteride significantly reduced clinical progression (doxazosin-39% risk reduction, P < 0.001; finasteride 34% risk reduction P = 0.002) compared to placebo. The combination of doxazosin and finasteride however resulted in a 66% risk reduction compared with placebo (P < 0.001). Mean follow-up was 4.5 years. The authors conclude that long-term combination therapy with doxazosin and finasteride was safe and significantly reduced the risk of clinical progression of BPH and was superior to either drug alone (N Engl J Med. 2003;349:2387-2398).
T4 Alone is OK for Hyperthyroidism Therapy
Hypothyroidism is one of the most common clinical disorders in general practice. Controversy about replacement therapy has raged for years regarding the need for liothyronine (T3) in addition to thyroxine (T4). A new study from Bethesda suggests that thyroxine alone is optimal therapy. In this randomized, double-blind, placebo-controlled trial, 46 hypothyroid patients were randomized to their usual dose of levothyroxine, or combination therapy in which their dose of levothyroxine was decreased by 50 mg/d, and liothyronine 7.5 mg was given twice daily for 4 months. TSH levels were followed and remained stable throughout the study. The main outcomes were scores on the hypothyroid specific health-related quality of life questionnaire, body weight, serum lipid levels, and 13 neuropsychological tests before and after treatment. After 4 months, body weight and serum lipid levels were unchanged in both groups. Quality of life scores improved in both groups (23% improvement levothyroxine group [P < .001], 12% improvement combination group [P = .02]). There is no statistical difference in neuropsychological testing between the 2 groups except for better performance in the Grooved Peg Board test in the levothyroxine group. The authors conclude combination therapy with levothyroxine plus liothyronine offers no advantage over single therapy with levothyroxine for the treatment of hypothyroidism (JAMA. 2003;290:2952-2958).
FDA Ban on Ephedra Awaits Final Ruling
The FDA has issued a consumer alert, banning the dietary supplement ephedra. The ban will become effective 60 days after the publication of a final rule stating that dietary supplements containing ephedra represents an unreasonable risk of illness or injury. This unprecedented move, the first time the FDA has banned a supplement, comes after several high-profile deaths linked with ephedra including professional athletes. Overall, the FDA has reports of 155 deaths associated with ephedra and more than 16,000 complaints. The drug is commonly used for weight loss and is present in many over-the-counter preparations. It is also widely used in Chinese herbal medicine practices, where it is known as Ma huang, and has been a staple of therapy for thousands of years for a variety of ailments including asthma and fever. The FDA has allowed an exemption for practitioners of Chinese medicine as long as is not used in high dose for weight loss.
This supplement was written by William T. Elliott, MD, FACP, Chair, Formulary Committee, Kaiser Permanente, California Division; Assistant Clinical Professor of Medicine, University of California-San Francisco. Telephone: (404) 262-5413. E-mail: [email protected]. In order to reveal any potential bias in this publication, we disclose that Dr. Elliott reports no consultant, stockholder, speaker’s bureau, research, or other financial relationships with companies having ties to this field of study.
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