Two white persons, a male aged 41 year and a woman at the same age have been taken chloroquine phos

Fråga: Two white persons, a male aged 41 year and a woman at the same age have been taken chloroquine phosphate 160 mg (Klorokinfosfat, ACO) 6 times a week as malaria prophylaxis from 830207 to 830325. The man experienced itching after some days treatment. During the first 3 weeks no skin changes but after 3 weeks macular papular skin changes over the whole body. The man experienced that the itching was more intense 3-6 hours after each dose. After stopping drug intake the symptoms have become less intense.

The woman experienced itching over hands, abdominal area and arms some weeks before stopping drug intake.

The two persons have together visited Gambia. No other diseases are suspected. How well documented is itching after treatment with chloroquine in prophylactic doses?

Sammanfattning: Chloroquine associated pruritus is well documented in the literature but the mechanism of action is unknown. The occurence of pruritus seem to be higher in negroid patients than in whites.

Svar: Most reference books (1-3) state pruritus as a side effect of chloroquine, while a single source (4) fails to mention any world of pruritus except for saying that hypersensitivity reactions limited to rash can occur. When using chloroquine for acute malarial attacks mild and transient headache, visual disturbances, gastrointestinal upsets and pruritus can occur (2). Prolonged chronic medication for suppressive purposes causes a few significant side effects and only rarely must the drug be discontinued because of intolerance (2). None of the symptoms is serious and readily disappear when the drug is withheld.

In a review (5) the occurrence of pruritus as a distinct and interesting skin reaction due to chloroquine therapy was emphasised. The pruritus is wide spread and seen mainly over the hands, feet and scalp. The reactions occur in male and female adult patients, predominantly Negroe, who are on the accepted therapeutic doses of chloroquine for clinical malaria. In over half the cases the pruritus is sufficiently distressing to withhold the patient from work. The patient is unable to walk because he can not go more than a few minutes without stopping.

The reaction is not associated with erythema, urticaria, papules, vesicles, or other skin changes. The mucus membranes of the eyes, mouth and genitalia are remarkably unaffected.

Recently clinical features of chloroquine associated pruritus have been reviewed (6,7). One report (7) concerns a 23-year old, white nurse who was given chloroquine by mouth 600 mg base initially and then 300 mg base at 8, 24 and 48 hours. After the last dose she awoke with severe itching over her entiry body, particylarly over her palms and her feet. She was unable to sleep and described the itching as being deep "under the skin" and that "there was no way to relieve it". The symptoms observed in this European patient were identical with those previously reported in Nigerians (6).

The incidense of this type of itching in Nigerians is reported to be not less than 8 per cent and more probably up to 15 per cent (6). One may speculate about the biological mechanism of chloroquine itching but no satisfactory explanation has been reported in the literature we have gone through.

Referring to the above 2 patients it is probable that the patients have been affected by chloroquine induced pruritus since the case histories are of those type reported in the literature except the fact that some macular papular skin changes were found in those two patients. 1 Avery, Drug treatment, 1980; 2nd ed: 1189-1190

2 Goodman and Gilman, The pharmacological basis of therapeutics, 1980; 6th ed: 1042-1046
3 Martindale, Extra pharmacopoeia, 1982; 28th ed: 395-397
4 Meyler/Herxheimer, Side effects of drugs 1980; 9: 482-483
5 Ekpechi OL, Okoro AN: A pattern of pruritus due to chloroquine. Arch Dermatol 1964; 89: 631-632 (letter)

6 Olatunde A: The practical and therapeutic implications of chloroquine-induced itching in tropical Africa. Afr J Med Sci 1977; 6: 27-32 7 Spencer HC, Poulter NR, Lury JD, Poulter CJ: Chloroquine-associated pruritus in a European. Br Med J 1982; 285: 1703-1704