Which drug example illustrates tissue binding to pigments influencing distribution?

Which drug example illustrates tissue binding to pigments influencing distribution?

• A. Chloroquine
• B. Aspirin
• C. Acetaminophen
• D. Metformin

Answer: (A)

Tissue binding to pigments can sequester a drug in pigmented tissues, leading to higher local concentrations and longer retention in those areas. Chloroquine is a classic example because it has a strong affinity for melanin, so it accumulates in pigmented tissues such as the eye. This binding helps explain why chloroquine distribution includes the ocular tissues and why prolonged exposure can raise the risk of retinal toxicity. The other drugs listed do not have meaningful pigment binding, so their distribution is not driven by pigment sequestration; instead, their distribution depends more on factors like lipophilicity, plasma protein binding, and tissue perfusion.

Tissue binding to pigments can sequester a drug in pigmented tissues, leading to higher local concentrations and longer retention in those areas. Chloroquine is a classic example because it has a strong affinity for melanin, so it accumulates in pigmented tissues such as the eye. This binding helps explain why chloroquine distribution includes the ocular tissues and why prolonged exposure can raise the risk of retinal toxicity. The other drugs listed do not have meaningful pigment binding, so their distribution is not driven by pigment sequestration; instead, their distribution depends more on factors like lipophilicity, plasma protein binding, and tissue perfusion.