Efficacy and tolerability of a new synergized pyrethrins thermofobic foam in comparison with benzyl benzoate in the treatment of scabies in convicts: the ISAC study (Studio Della scabbia in ambiente carcerario)

Background Scabies is a very common skin infection in convicts. The SIMSPE Society (Societa Italiana di Medicina e Sanita Penitenziaria) has organized and conducted a multicentre, randomized, comparative, parallel group, investigator-blinded trial to evaluate the efficacy and tolerability of synergized pyrethrins foam (PF) in comparison with benzyl benzoate (BB) lotion. Methods A total of 240 convicted patients, enrolled in eight National Jail Institutions, with a clinical diagnosis of scabies, were treated with PF (n = 120) for three consecutive days or BB (n = 120) for five consecutive days. Primary study endpoints were the clinical cure rate and the local tolerability. Secondary endpoints were clinical evolution of scabietic lesions and itching intensity. Study outcomes were assessed using appropriate semiquantitative scores at baseline and after 2 and 4 weeks. A second treatment cycle was applied if after 2 weeks the patient was not judged clinically cured. Results At week 2, a total of 75% (95% CI: 66-82%) and 71% (95% CI: 62-78%) of patients showed a complete clinical cure rate in the PF and BB groups, respectively. At week 4, the percentage of totally cured patients increased up to 95% (95% CI: 89-97%) and 91% (95% CI: 83-94%) in the PF and BB groups, respectively (P = NS between groups). At week 4, 5% in the PF group and 9% in the BB group complained of itching. Burning and irritation after treatment applications were more common in the BB group in comparison with the PF group. The tolerability score was better in the PF group in comparison with to BB group (2.9 vs. 2.2; P = 0.0001). A total of 95% of patients in the PV group had a good tolerability score (i.e. = 3) in comparison with 41% in the BB group. Conclusion Our results show that a 3-day treatment with pyrethrins thermofobic foam is at least as effective as a 5-day treatment with benzyl benzoate lotion in convicted subjects with scabies. The foam formulation is better tolerated than the benzyl benzoate lotion.