Chloroquine-induced Pruritus: Familial Aggregation and possible Genetic Basis

Abstract

1152 attendants comprising 40% mole and 60% female subjects at urban private clinics and rural health centres in Ghana were interviewed by questionnaire. Enquiry was made into the occurrence of chloroquine-induced pruritus in themselves, their spouses, their children, their siblings and their parents. The questionnaire included the following details:- (a) self-medication for febrile illnesses (b) the number of tablets of chloroquine that induced pruritus. (c) the time of onset and duration of pruritus (d) the method of relief of pruritus 44.8% of respondents had experienced itching on taking chloroquine. 23.3% itched on being given chloroquine intramuscularly and 95% of these itched on oral chloroquine. The rate of itching on self-medication with chloroquine alone or with other drugs was 41%. 33.9% itched each time they took chloroquine and 30.9% itched at least once after taking chloroquine. The prevalence rate of chloroquine induced pruritus in this study was found to be between 30. 9% and 44.8%. of the respondents who knew about itching among their close relatives, 50.7% (309/609) had siblings who itched, 29.3% (184/628) had children who itched, and 21.9% (166/759) had parents who itched on taking chloroquine. The results describe a pattern suggestive of strong familial aggregation and thus a possible genetic basis for chloroquine-induced pruritus. In addition, a pathway a/inheritance leading to male preponderance in off-springs of respondents who itch has been established. The minimum number a/tablets required to induce itching was found to be 2, equivalent to 300mg base chloroquine. 42.2% o/respondents started itching within 2 hours, 24.1% between 2 and 6 hours, and 33.3% after 6 hours. Of the 57.6% who took drugs for relief of pruritus, 89.7% took antihistamine preparations. However there was no significant difference between those who took the drug before or after chloroquine ingestion, with regard to relief of pruritus.