Chloroquine is given as 600 mg loading dose because:
It is rapidly absoed
It is rapidly metabolized
It has increased tissue binding
It is rapidly eliminated
Oral absorption of CQ is excellent. About 50% gets bound in the plasma. It has high affinity for melanin and nuclear chromatin: gets tightly bound to these tissue constituents and is concentrated in liver, spleen, kidney, lungs (several hundred-fold), skin, leucocytes and some other tissues. Its selective accumulation in retina is responsible for the ocular toxicity seen with prolonged use. ESSENTIALS OF PHARMAXOLOGY page no.822
Chemotherapy