Primaquine belongs to 8-Amino Quinoline derivative which is used to treat malaria Indication of Primaquine: Radical cure or...
Primaquine belongs to 8-Amino Quinoline derivative which is used to treat malaria
Indication of Primaquine:
Radical cure or prevention of
relapse in vivax malaria; after termination of chloroquine phosphate suppressive
therapy in areas where vivax malaria is endemic [1].
SAR
OF PRIMAQUINE
·
Methoxy group at Position
6 is responsible for optimum activity but this group is not essential for
antimalarial activity.
·
If we replace the
methoxy group at position 6 by hydroxyl group.it will show comparable (same) activity.
While when ethoxy group is attached it will show low or negligible activity
·
If we replace
methoxy group by methyl group at position 6 the compound will become inactive
·
Additional
substitution on the quinoline nucleus tends to decrease both activity and
toxicity.
·
The reduction of
quinoline nucleus ( hetro ring ) at position 1 into 1,2,3,4 tetra hydro
derivative (i.e primaquine ) this will show same pharmacological effect but its
potency and toxicity will be decreases means require high dose .
·
In amino acid side
chain, there are two amino group, for optimum activity, the distance between
the two nitrogens of amino acid side chain should be 3-6 or 4-6 carbons means
if less than 3 carbons, the activity will be decreases or if more than 6 carbons
than also decreases.
·
The optimal
activity is obtained when the alkyl chain contains 4 to 6 carbon atoms. The
greatest activity appears to be achieved in alkyl groups containing 5 carbon
atoms.
·
Any substitution
on the quinoline ring will lead to decrease its antimalarial activity.
References
1. Tatro DS, Borgsdorf
LR. A to Z drug facts. Facts & Comparisons; 2003.