Chloroquine phosphate tablets, 0.5-gram (each contains 300-mg of
(2) Chloroquine hydrochloride injection, 5-ml ampules containing equivalent
of 200-mg of base.
a. Uses. Since primaquine, a tissue schizonticide, is not effective against blood
schizonts, it will not provide immediate relief to acute symptoms of malaria such as
fever. However, it is capable of preventing infection because of P. falciparum if it is
administered soon after the mosquito bite. It is used along with blood schizonticides in
radical (complete) cures of the relapsing malarias, that is, those due to P. vivax, P.
malariae, and P. ovale. Unfortunately, there are some strains of P. vivax, which are
partially resistant to primaquine. Since primaquine inhibits gametocytes, it is effective in
preventing the transmission of malaria to other persons by way of mosquitoes.
(1) Primaquine sensitivity. Some people have an inherited sensitivity to
primaquine because of a deficiency of a substance called G6PD, which is important to
metabolism in the red blood cells. They may react to large doses of primaquine with
chills, malaise, and weakness, resulting from hemolysis. The incidence of this
deficiency is much greater among people whose ancestors have lived in areas where
malaria due to P. falciparum is common. These people include blacks, Greeks,
Iranians, Sardinians, and Sephardic Jews. The prophylactic dose, such as that found in
the CP tablet, seldom causes any intense reaction. However, when these groups are
treated with primaquine for preexisting malarial infections, that is, when the doses are
greater, the clients should be observed closely for hemolysis. Each such client
receiving primaquine should be told to report signs of hemolysis, such as red or dark
coloration of the urine.
(2) Side effects. The side effects of primaquine may include difficulty in
focusing, itching, nausea, headache, and abdominal cramps (which antacids relieve).
Some blood disorders may occur.
c. Contraindications. Primaquine should not be given to clients with a
tendency toward active rheumatoid arthritis, granulocytopenia, lupus erythematosus, or
any very serious systemic disease. Primaquine should not be given concurrently with
quinacrine or any drug, which depresses the bone marrow. Large doses of primaquine
should usually be avoided.
d. Dosage. Primaquine is given orally. The usual dose is one tablet daily for 14