Analgesics PDF

ANALGESICS DR. SABIR MEKKI HASSAN These are drugs that selectvely relieve pain by actng in CNS or on peripheral pain mechanisms, without signifcantly altering consciousness. Types: 1. Opiates and opioids. 2. NSAIDs. 3. Analgesic antpyretcs. 4. Drugs for neurological pain. Opiates and opioids:...

ANALGESICS DR. SABIR MEKKI HASSAN These are drugs that selectvely relieve pain by actng in CNS or on peripheral pain mechanisms, without signifcantly altering consciousness. Types: 1. Opiates and opioids. 2. NSAIDs. 3. Analgesic antpyretcs. 4. Drugs for neurological pain. Opiates and opioids: A narcotc drug is a psychoactve drug that produces analgesia, narcosis and addicton. 1. opiates: are groups of naturally occurring compounds derived from the juice of the poppy plant (papaver somineferum). It contains: a. Phenanthrene ring:( more CNS efect, cause addicton, spaspmogenic) morphine, codeine and thebaine. b. Benzylisoquinoline ring: (less CNS efects, do not cause addicton, spamsolytc efect) Papaverine, noscapine and narcine 2. opioids: much broader class of agents that are either producing opium like efects or binding to opioid receptors. a. semi synthetcs: Heroin( acytle morphine), hydromorphone.. b. synthetcs: 1. agonist: meperidine, methadone, taramadol. 2. Mixed agonist antagonist: nalorophine, nalbuphine, pentazocin, butorphanol, bupermorphine. 3. Antagonist: naloxone, naltrexone.  Morphine Main medical uses: Management of acute and chronic pain. Pulmonary edema. It is abused for its euphoric and pain relieving efect. It causes addicton (physical and psychological dependence). Routes of administraton: Mainly given orally, IV, IM,SC, epidural. After oral intake only 25% of the dose is bioavailable. receptors: Mu, delta an kappa. Mechanisms of pain relief: 1. Interference with neurotransmiter (substance P) in the posterior horn cells of the spinal cord. 2. Inhibiton of neurotransmission from higher(supra-spinal) brain centers. 3. Decreases noradrenalin(enhances emotonal sensaton of pain) release in the brain. 4. Peripherally ,decreases pain sensaton in infamed tssue. Morphine dose not relieve itching but it causes and increases it for: 1. Itching has a diferent pathway. 2. Morphine causes histamine release. Pharmacological efects: CNS:- 3. Analgesia(physical and emotonal pain). 4. Euphoria. 5. Miosis. 4. Vagal stmulaton. 5. Nausea and vomitng. 6. Respiratory depression. 7. Cough suppression. 8. Increased intra-cranial pressure. CVS:- 1. Bradycardia. 2. Hypotension( Vagal stmulaton and histatmine release). GIT:- 1. Constpaton and colic. 2. Gall bladder spasm. Genito-urinary:- 1. Urgency of micturaton and difculty of passing urine. 2. Prolongaton of labour. Resp.: 3. Bronchiconstricton. 4. Cough suppression. Skin:- Itching. Acute intoxicaton( overdose):- 1. Respiratory:- depression, bronchospasm and non- cardiogenic pulmonary edema( acute lung injury). 2. CNS depression preceded by anxiety, agitaton, euphoria or dysphoria. 3. Seizures mostly due to hypoxia. 4. Pin-point pupils. 5. CVS:- Hypotension and bradycardia. 6. hypothermia. 7. prurits. 8. GIT:- constpaton. Causes of death:- 1. Resp. depression. 2. Pulm. Edema. 3. Dysrhythmia. 4. irreversible brain damage due prolonged hypoxia. Fatal dose: 100 mg 0r 2-3 grams of opuim. DD of pin-point pupils:- Pontne hemorrhage, OPC, carbamate. Investgatons: ABG, pulse oximetry, ECG, urea, electrolytes, creatnine, glucose, CXRR, AXRR, urine screening. Management:- 1. Emergency measures(ABCD). 2. Antdote: naloxone( Narcan ). 3. Eliminaton: GL, AC, Whole bowel irrigaton. 4. Supportve treatment: IV fuids, ant- arrhythmic, ant-convulsants , management of Pulm. Edema, management of coma. Withdrawal: Anxiety, agitaton, hypertension, yawning, lacrimaton, running nose, dilated pupils, tremors, piloerecton, vomitng, diarrhea, muscle aches. Death may be due to dehydraton and collapse. Management:- 1. Admission and good diet. 2. Detoxifcaton: Methadone, clonidine, supportve care( relief of pain, control of vomitng and diarrhea, adequate rehydraton). Naltrexone( outpatent treatment once detoxifcaton is complete. 3. psychotherapy, rehabilitaton and follow up. Post mortem: Asphyxial death, smell of opium, injecton sites, morphine is detected in body fuids(urine). ThnQ