Which of the following is least narcotic opioid?: (A) Morphine, (B) Codeine, (C) Heroin, (D) Papaverine
Answer is D. Papaverine is devoid of opiod or analgesic activity. Morphine and codeine are natural opium alkaloids and heroin a semi synthetic derivative. Hence all three have good narcotic action. Ref: KD Tripathi 8th ed.