The New Straits Times, June 19,1995
Q: Recently, I read a newspaper report on a 20-year-old Englishman who developed depression and amnesia after taking the antimalarial drug mefloquine. Is true that this drug could have caused these problems?
A: Mefloquine is a recently-introduced antimalarial drug effective as a prophylaxis (prevention against malaria) and as a treatment for all forms of malaria.
When used prophylactically, mefloquine (250mg) one tablet per week for four weeks, followed by one tablet every other week, is recommended. Adverse effects of mefloquine from the prophylactic dose are uncommon.
However, standard doses used to treat malaria have been observed to cause various central nervous system disturbances such as dizziness, syncope, and asthenia.
It is estimated that about less than one per cent of patients on mefloquine will develop these reactions.
Other neuropsychiatric problems including seizures, hallucinations, confusion and depression have also been reported. WHO reported a number of neuropsychiatric cases following ingestion of mefloquine with doses as low as two tablets.
Symptoms which occurred during the second week of drug administration included disorientation and decreased consciousness. All patients however recovered without any special treatment.
Based on the information given, it is difficult to ascertain the exact cause of depression and amnesia in this man. Depression is well documented with mefloquine but we have yet to receive any report that is causes amnesia. This, however, does not mean that the drug could not cause amnesia.
In addition, it also seems very unlikely for anyone taking the drug at prophylactic doses to develop significant adverse reactions to the central nervous system like those experienced by the man.
In addition, it also seems very unlikely for anyone taking the drug at prophylactic doses to develop significant adverse reactions to the central nervous systems like those experienced by the man.
Studies of prophylactic dosage in volunteers have not produced the severe adverse effects associated with therapeutic dosage. The situation, however, may be different if larger doses are used or if other medications are being taken concurrently.
