Chloroquine, adverse drug reaction

Sensory system Chloroquine-induced retinopathy is a well-documented adverse drug reaction. The retinopathy can occur even after usage of the drug has stopped. A case is reported of a 52-year-old woman with Sjogren s syndrome who developed chloroquine retinopathy lOyears after stopping the drug [14 ]. 

Hydroxychloroquine (Plaquenil), like chloroquine, is a 4-aminoquinoline derivative used for the suppressive and acute treatment of malaria. It also has been used for rheumatoid arthritis and discoid and systemic lupus erythematosus. Hydroxychloroquine has not been proved to be more effective than chloroquine. Adverse reactions associated with its use are similar to those described for chloroquine. The drug should not be used in patients with psoriasis or porphyria, since it may exacerbate these conditions. 

Amodiaquine (Camoquin) is another 4-aminoquinoline derivative whose antimalarial spectrum and adverse reactions are similar to those of chloroquine, although chloroquine-resistant parasites may not be amodi-aquine-resistant to the same degree. Prolonged treatment with amodiaquine may result in pigmentation of the palate, nail beds, and skin. There is a 1 2000 risk of agranulocytosis and hepatocellular dysfunction when the drug is used prophylactically. 

The increasing prevalence of strains of P. falciparum that are resistant to chloroquine (CQ), a blood schizontocide which had been efficacious, safe, accessible and affordable, poses a serious problem for malaria control, predisposing Afiica to an unprecedented situation since the only affordable treatment options are rapidly losing therapeutic efficacy. Drug-resistant strains of P. falciparum are endemic in many areas of the world and the majority of conventional antimalarial drugs have been associated with treatment failure. These developments and the difficulty of creating efficient vaccines, coupled with adverse reactions to chemotherapy, underline the urgent need for novel, cheap, safe and... 

The authors of the report attribute the dystonia to an interaction between metronidazole and chloroquine as she had taken both drugs alone without adverse effect. However, they do not fiilly assess the possible contribution of promethazine, which is known to cause dystonias. It is therefore possible that the reaction seen was an adverse effect of the promethazine, or perhaps even an interaction between promethazine and chloroquine. No general recommendations can therefore be made from this single report. 

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