**Core Concept**
Chloroquine is a 4-aminoquinoline derivative used in the treatment and prophylaxis of malaria. Its pharmacokinetics and pharmacodynamics are influenced by its ability to bind to tissues, particularly the liver and erythrocytes, which affects its distribution and concentration in the body.

**Why the Correct Answer is Right**
The correct answer is C. It has increased tissue binding. Chloroquine is known to bind extensively to melanin in the skin and retinal pigment epithelium, as well as to the liver and erythrocytes. This increased tissue binding leads to a higher volume of distribution (Vd) and slower elimination half-life, necessitating a loading dose to achieve therapeutic concentrations. The loading dose allows for rapid achievement of effective plasma concentrations, ensuring effective prophylaxis or treatment of malaria.

**Why Each Wrong Option is Incorrect**
**Option A:** Chloroquine is not rapidly absorbed; its absorption is incomplete and varies depending on the formulation, with peak plasma concentrations typically occurring 6-8 hours after oral administration.
**Option B:** Chloroquine is metabolized in the liver by the cytochrome P450 enzyme system, but its rapid metabolism is not the primary reason for the loading dose.
**Option D:** Chloroquine is not rapidly eliminated; its elimination half-life is approximately 1-2 weeks, which allows for prolonged antimalarial effects.

**Clinical Pearl / High-Yield Fact**
When prescribing chloroquine, consider the patient's melanin content, as increased melanin binding can lead to prolonged half-life and increased risk of retinal toxicity. This is particularly relevant in individuals with darker skin tones.

**✓ Correct Answer: C. It has increased tissue binding**