## Distinguishing Chloroquine from Quinine ### Pharmacokinetic & Dosing Profiles | Feature | Chloroquine | Quinine | |---------|-------------|--------| | **Half-life** | 3–5 days | 8–11 hours | | **Dosing frequency** | Once weekly (maintenance) | Thrice daily (TID) | | **Oral bioavailability** | Excellent (70–90%) | Moderate (60–80%) | | **Cinchonism at therapeutic doses** | Absent | Present (tinnitus, vertigo, visual disturbance) | **Key Point:** Cinchonism (tinnitus, hearing loss, blurred vision, vertigo, nausea) is a hallmark **adverse effect of quinine** that occurs at therapeutic doses and worsens with higher concentrations. Chloroquine does not cause cinchonism at standard therapeutic doses. ### Clinical Pearl **High-Yield:** Quinine is now reserved for severe malaria (especially cerebral malaria and severe P. falciparum) when IV artesunate is unavailable. Its narrow therapeutic index and cinchonism make it unsuitable for routine prophylaxis or uncomplicated malaria. ### Mechanism Behind Cinchonism Quinine's ototoxicity and CNS effects are dose-dependent and related to: - Direct cochlear toxicity - Increased intracranial pressure - Hypoglycemia (quinine stimulates insulin release) Chloroquine lacks these effects at therapeutic concentrations, making it the preferred agent for routine malaria treatment and prophylaxis [cite:KD Tripathi 8e Ch 51].
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