Dosing error with antimalarial medicine

 

Recently a woman notified our organization after realizing her doctor prescribed the incorrect dose for an antimalarial medicine. The woman, who was soon going to travel to a part of the world where malaria is present, discussed with her doctor about taking medicine to prevent malaria. Having taken antimalarial medicine in the past, the woman asked her doctor to prescribe chloroquine (the same medication she has taken many years ago).

Chloroquine phosphate is available as a generic in two sizes: 250 mg and 500 mg tablets. In addition to preventing malaria, chloroquine can also be prescribed for treating malaria and other diseases such as Lupus, Rheumatoid Arthritis and Amoebiasis (an intestinal illness transmitted when someone eats or drinks something that's contaminated with a microscopic parasite). Depending on the reason for treatment, the dose and how often the medicine is taken can vary.

For treatment of malaria, the typical dosage of chloroquine is as follows1:

  • Take chloroquine 500 mg once on the week prior to leaving to go to the area where malaria transmission occurs.
  • Take chloroquine 500 mg once per week while you are in the area where malaria transmission occurs.
  • Take chloroquine 500 mg once per week for 4 consecutive weeks after leaving the area where malaria transmission occurs.

The doctor agreed to prescribe the medicine for the woman and called it into her local pharmacy. When the woman arrived at the pharmacy, they told her that they did not have enough of the 500 mg tablets to fill the prescription. In turn, the pharmacy substituted some of the 500 mg tablets with two 250 mg tablets.

The woman left the pharmacy with 25 tablets of chloroquine 500 mg and 100 tablets of chloroquine 250 mg (see figure 1). In total, the woman had 75 doses of chloroquine 500 mg. The instructions on the container were to take one chloroquine 500 mg daily.

malaria dosing error

Luckily, the woman had remembered taking this medicine in the past. She was puzzled by the amount of tablets, because the previous time she did not take the medication every day. After looking up a typical dosing schedule on the Center for Disease Control and Prevention (CDC) website, she immediately contacted her doctor and the error was detected.

In this case, the error was prevented since the woman was familiar with the medicine and how frequently it should be taken. She also knew enough to check online and with her doctor before taking the medicine.

If you are ever given a prescription and have concerns about the dose, frequency, pill shape/color, or something doesn't seem right, don't hesitate to contact your doctor or pharmacy with questions.

1. The Centers for Disease Control and Prevention (CDC). Medicines for the Prevention of Malaria While Traveling Chloroquine (Aralen™). http://www.cdc.gov/malaria/resources/pdf/fsp/drugs/Chloroquine.pdf. Accessed March 9, 2015.

Created on March 11, 2015

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