Barbiturate

rasel mahbub jnu

1. Barbiturates Presented By Rasel mahbub & Ananta sutradhar

2. CNS depressants CNS depressants are substances that can slow brain activity by selectively depressing neuronal activity in posterior hypothalamus. Barbiturates are derivatives which is synthesized by urea & malonic acid. Malonic acid Barbituric acid Barbiturates It was first prepare by a german scientist Adlof Von Baeyer in 1864,combining urea from animal & malonic acid from apples.

3. It was used as sleeping aid(hypnotic only) from 1903-1950.Since 1950 they have been popular drug in the UK,these were previously popular drug of abuse. It was estimated that 27000 peoples died from barbiturates overdose in the UK between 1959-1974.

4. Synthesis

5. Progressive grade of CNS depressant Sedation Hypnosis Narcosis General anaesthesia Coma Death

6. Classification according to duration of action .Ultra-short acting Properties 1.Theopental act within second 2.Hexo-barbitone D/A:30 min Main use: as I/V anaesthesia

7. Short acting Properties 1.Pento-barbitone D/A:2 hours 2.Quino-barbitone Main use: as sedative

8. Intermediate acting Properties 1.Amilo-barbitone D/A:3-6 hour 2.Allo-barbitone Main use 3.Buto-barbitone Hypnotic 4.Vin-barbitone

9. A)Long acting Properties 1.Barbitone D/O:>6 hour 2.Pheno-barbitone Main use: 3.Mepho-barbitone Anticonvulsant 4.Apo-barbitone

10. According to chemical structure 1.Oxybarbiturate (If oxygen is present) 2.Thiobarbiturate (If oxygen is replaced by sulpher )

11. Mechanism Of Action Barbiturates are general depressants of all cell of the body,acting as a cellular histotoxic agent.But the cell of the CNS are more sensitive to barbiturate action. 1.Barbiturate induce sleep by selectively depressing RAS in the brain stem. 2.Barbiturate selectively depress neuronal activity in posterior hypothalamus,amygdaloid nucleus& limbic structure (CNS depression) 3.Barbiturates depress monosynptic pathway of spinal cord( anticanvulsion ) 4.Barbiturates have also GABA like activity or enhance GABA activity.

12. Mechanism of action Barbiturate+GABA Activation of GABA receptor Opening of chloride channel Increase the duration of GABA gated channel opening Hyperpolarisation of cells Depression of CNS

13. Pharmacological action of Barbiturates A.On CNS 1.Mild degree of sedation to general anaesthesia . 2.Anticonvulsant effect. 3.Respiratory centre depression B.On CVS 1.Hypotension 2.Decrease heart rate 3.Circulatory collapse

14. C.On liver 1.Enzyme induction,so increase metabolism of itself & other drugs. 2.Stimulate glucoronyl transferase . D.On kidney 1.Antidiuretic effect (increase ADH) 2.Decrease urinary output by depressing GFR

15. E.On eye 1.No effect (normal dose) 2.Miosis ( toxic effect) F.On GIT 1.Constipation (on prolong use)

16. Structure

17. Indication 1.As anticonvulsant tetanus eclampasia , epilesy cerebral haemorrhage convulsant drug poisoning during surgical anaesthesia 2.As sedative & hypnotic 3.Intravenous anaesthesia 4.Hyperbilurobinaemia & kernicterous

18. 5.Haemolytic jaundice 6.Cholestasis 7.In narco analysis & narcopathy 8.Identifying the dominant cerebral haemisphere for speech prior to neuro surgery 9.Kernicterus in children

19. Contraindication 1.Pulmonary insufficiency,pulmonary emphysema 2.In idiosyncratic patient 3.Acute intermittent pophyria 4.In impaired renal function 5.In hepatic failure 6.Ptient with suicidal tendency 7.CCF & hypovolmic shock

20. Adverse effect of Barbiturates 1.Pain;Localized or diffuse myalgic,neuralgic or arthritic pain especially in psychoneurotic patient. 2.Allergic skin lessions 3.After effects drowsiness Hangover effect Over excitement Night mares & night terrors weakness & lethargy

21. 4.Drug automatism 5.Enzyme induction (so tolerance develops rapidly) 6.Idiosyncratic reaction:barbiturates precipitate attacks of acute porphyria in sussceptible individual.

22. Doses of barbiturates The typical dose of phenobarbital use as anticonvulsant,, For adult:50-100 mg,2/3 times per day For newborn:2-4 mg per kilogram of body weight per day For infant:5-8 mg per kilogram pf body weight For sedation before surgery 100-200 mg,one hour before surgery

23. Commercial brand name available in BD Brand Name Manufacturer Barbit Incepta pharma Genesia DS Square Nelepsin Beximco Parotin ACI pharma

24. Sedative:Drugs that reduce anxiety,excitement & exert calming effect without effecting mental function.It is usually lower or normal dose,not higher dose. Hypnotic:Drugs those cause of sleep are called hypnotic. Usually higher dose not normal or lower dose Sedative given day time hour,they makes patient drowsy not sleep Hypnotics are given at night of sleep