CNS Analgesics PDF

Mechanism of action: μ, δ, κ agonists Therapeutic uses: 1-Analgesic: Acute severe pain (e.g. postoperative, fracture and Acute MI) & Cancer pain. Meperidine (pethidine) is preferred in biliary colic as it has atropine like action. 2-Acute pulmonary edema: sedative and cause pulmonary vasodilata...

Mechanism of action: μ, δ, κ agonists Therapeutic uses: 1-Analgesic: Acute severe pain (e.g. postoperative, fracture and Acute MI) & Cancer pain. Meperidine (pethidine) is preferred in biliary colic as it has atropine like action. 2-Acute pulmonary edema: sedative and cause pulmonary vasodilatation Æ ↓ pulmonary pressure 3-Anaesthesia: Fentanyl is preferred as it is more potent. 4-Antitussive: Codeine (less addicting) & dextromethorphan (non-addicting) are preferred as cough sedatives. 5-Anti-diarrheal: loperamide & diphenoxylate are preferred (non-addicting, more specific and less side effects) Adverse effects: 1-Respiratory depression: the most important complication of acute administration, more common in patients with respiratory problems, it is treated by an antagonist (naloxone) 2-Bronchospasm, Biliary spasm, Urine retention & delayed labor ,Vomiting, constipation, ileus Truncal rigidity ,Hypotension and bradycardia 3-Addiction and withdrawal syndrome is the most important complication of chronic administration. Contraindications and precautions: 1-Hypovolemia to avoid hypotension 2-Head injury (miosis mask diagnosis & increase ICP) 3-Acute abdominal pain (mask diagnosis) 4-Respiratory disease (bronchial asthma-COPD) & liver disease 5-Late in labor (to avoid asphyxia neonatorum) ◼ Salt & water retention (hypertension & edema) ⚫ ⚫ ⚫