NAPA, CALIF. – "You are almost never going to see a study where the sponsoring company’s product wasn’t at least as good if not better," than the comparator drug, said Dr. Joseph F. Fowler. But that reality does not necessarily mean the study results don’t provide good clinical information.
"Once a drug goes generic, you’re almost never going to see any further study on it."
Most comparison studies are done by pharmaceutical companies and are limited to comparing competing drugs to the company’s branded drugs, explained Dr. Fowler, a dermatologist at the University of Louisville (Ky.). Also, "once a drug goes generic, you’re almost never going to see any further study on it."
Dr. Joseph F. Fowler
Dr. Fowler discussed several comparison studies that run across the dermatology gamut at the meeting, and then asked the audience which drug they prefer.
Ivermectin Vs. Malathion for Lice
In a recent comparison of oral ivermectin to malathion lotion for difficult-to-treat head lice, ivermectin came out slightly on top in terms of clearance at day 15 (95% vs. 85%, respectively), he reported.
In the multicenter trial, 812 patients from 376 households were randomized to receive 400 mcg/kg of body weight of ivermectin or 0.5% malathion lotion on days 1 and 8. The study patients had lice that were not cleared with a topical insecticide 2-6 weeks before study enrollment (N. Engl. J. Med. 2010;362:896-905).
"I tend to use more ivermectin when I see these patients than I ever used to, and I tend to use less topicals," said Dr. Fowler. However, systemic drugs probably have more of a chance of causing toxicity than topicals.
Ivermectin Vs. Permethrin for Scabies
In another comparison of oral ivermectin, this time for scabies, permethrin came out slightly on top. Patients with scabies (n = 85) were randomized to treatment with 200 mcg/kg body weight of ivermectin or a single topical application of 5% permethrin cream. Clearance was seen in 95% of permethrin-treated patients, compared with 70% of ivermectin-treated patients at 8 weeks (J. Am. Acad. Dermatol. 2000;42:236-40).
Topical permethrin was also found to be more effective than topical crotamiton, topical lindane, and oral ivermectin for scabies in a Cochrane database system review (Arch. Dermatol. 2008;144:1638-40).
A show of hands in the audience found that the room was divided on their preferred treatment for head lice and scabies.
Griseofulvin Vs. Terbinafine for Tinea Capitis
A meta-analysis of seven randomized, controlled trials comparing griseofulvin and terbinafine in the treatment of tinea capitis resulted in a draw. However, griseofulvin was found to be slightly better for the Microsporum species, while terbinafine was found to be slightly more effective for the Trichophyton species (J. Am. Acad. Dermatol. 2011;64:663-70).
If cost is an issue, terbinafine is the cheaper drug, noted Dr. Fowler, who said the cost is about $4 in Kentucky. Further, treatment time is shorter with terbinafine at 4 weeks as compared with griseofulvin at 8 weeks. Also, terbinafine appears to be associated with fewer adverse effects than griseofulvin.
The majority of the audience members agreed, via a show of hands, noting their preference for terbinafine to treat children and adults with tinea capitis.
Tazarotene Vs. Adapalene for Acne
In a 16-week, multicenter, randomized, investigator-blinded study, patients treated once a day with tazarotene 0.1% cream had better acne lesion clearance than patients treated with adapalene 0.3% gel. More patients treated with tazarotene had at least a 50% reduction in lesions and less disease severity as compared with adapalene-treated patients (J. Drugs Dermatol. 2010;9:549-58).
However, tazarotene was somewhat less tolerated than adapalene, reported Dr. Fowler. Erythema occurred in 6% of tazarotene patients, dryness in 7%, and peeling in 11%. In the adapalene group, peeling was the only adverse event and was reported by 1% of patients.
By a show of hands, the majority of the audience members prefer adapalene.
Calcitriol Vs. Calcipotriol for Psoriasis
Calcitriol ointment was found to be better tolerated than calcipotriol for treating mild to moderate psoriasis in sensitive areas, such as on the face, around the hairline, and behind the ears (Br. J. Dermatol. 2003;148:326-33).
In the left-to-right, randomized, multicenter, investigator-blinded study, calcitriol 3 mcg ointment was compared with calcipotriol 50 mcg ointment in 75 patients. After 6 weeks, study patients reported preferring calcitriol ointment, which demonstrated "superior" tolerability and equal efficacy, reported Dr. Fowler. Adverse events (contact or irritant dermatitis) occurred in eight patients on the calcipotriol-treated side of their face (one patient reported dermatitis on both sides).
When asked to take cost and possible systemic adverse events into consideration, most audience members noted a preference for calcitriol ointment.