Anatomy Other topics and Adverse effects b6a5d62d Which of the following opioid analgesic acts primarily through K opioid receptors? A Pentazocine B Methadone C Buprenorphine D Pethidine High-Yield Explanation (Ref: KDT 6/e p464, 465) Pentazocine can cause dysphoric reactions (hallucinations) by stimulating the K receptors.