Final answer:
Primaquine is contraindicated in G6PD-deficient individuals due to the risk of hemolysis, as these individuals lack sufficient enzyme activity to protect their red blood cells from oxidative damage caused by the drug's metabolites.
Step-by-step explanation:
Anti-malarial drugs such as primaquine are contraindicated in patients with G6PD deficiency because they can cause hemolysis in these individuals. G6PD (glucose-6-phosphate dehydrogenase) is an enzyme that helps protect red blood cells from oxidative damage. In G6PD-deficient individuals, the red blood cells are more vulnerable to oxidative stress, which can be induced by primaquine's metabolites.
When these individuals take primaquine, the oxidative stress can lead to the breakdown of red blood cells, a condition known as hemolytic anemia. This risk of hemolysis is why primaquine is contraindicated for those with G6PD deficiency. This enzyme deficiency is more prevalent in certain populations and is particularly dangerous when the body is challenged by infections, certain drugs, or foods that increase oxidative stress.