What is Which antiemetic drug selectively blocks levodopa induced vomiting without blocking its anti-Parkinsonian action? and explain in detail?
LevodopaLev alone- Is less potent- As peripheral dopamine decarboxylase effective than central.Therefore, efficacy of drug decreases. As L-DOPA - Dopamine conveed in periphery > central - DA causes peripheral side effects D1 + - Hypotension B1 + - Arrhythmias a1 + - Hypeension CTZ + - Vomiting Antiemetic drugs: D2 antagonist : Metoclopramide Domperidone Cross BBB Can cause dystonia Do not cross BBB Do not cause dystonia DOC for levodopa induced vomiting 5HT3 5HT4 + No other action As domperidone do not cross BBB, it blocks levodopa induced vomiting without blocking it's anti - parkinsonism effect.