The drugs used in the present study were morphine sulfate (Temad Pharmaceutical, Tehran, Iran), agmatine sulfate, RX821002, UK 14 304 (Sigma, Germany), and yohimbine (Sigma, UK). The UK 14 304 ...

More expensive than morphine, hydromorphone is five times as potent. [10] Although its metabolites undergo renal clearance, the advantage of hydromorphone over morphine is that of its potency ...