HYPNOTIC AND SEDATIVE
•WHAT IS HYPNOTIC:---- Hypnotic are those drugs that produce sleep resembling natural sleep.
• WHAT IS SEDATIVE:------. These are the drugs that reduce excitement without producing sleep.
Qualitatively Hypnotics and sedatives produce a depression of the central nervous system, which is mainly quantitative.
♠ What is the classification of sedative- Hypnotic.:---------
• These are mainly three parts, but they also have subparts.
♥ 1). Barbiturates.
a). Phenobarbitone
b). Butobarbitone
c). Pentobarbitone
d). Thiopentone
e). Methohexitone
♥2). Benzodiazepines:-----
a). Diazepam
b). Flurazepam
c). Nitrazepam
♥3). Newer non benzo diazepines :-.
a). Zopiclone
b). Zolpodem.
• WHAT IS BARBITURATES:------
Barbiturates are derivatives of barbituric acid ( malonyurea) obtained by the condensation of urea and manolic acid.
Barbiturates acid itself does not possess Hypnotic activity. But Hypnotic activity is produced if the hydrogen atoms at position five are replaced by an alkyl or aryl group.
UREA + MANOLIC ACID = BARBITURIC ACID.
♠ WHAT IS THE CLASSIFICATION OF BARBITURATES:---
These are three types:--
1) Long acting:---
a) Phenobarbitone
2) Short acting:---
a) Butobarbitone
b) Pentobarbitone
3) Ultra short acting:--
a) Thiopentone
b) Methohexitone
♠ WHAT IS THE PHARMACOLOGICAL ACTION OF BARBITURATES:---
1). Central nervous system:-
Barbiturates produce all degrees of CNS depression like mild sedation, hypnosis, and general anesthesia.
a) Sleep :---
Barbiturate-induced sleep resembles natural sleep. But it decreases the time spent on 'rapid- eye- movement- sleep ( REM sleep)—also their hangover effect after awakening.
b). Analgesic effect:- Barbiturate do not releive pain without producing unconsciousness. But they enchance the analgesic effect of salicylate and para- amino phenol derivative.
c). Anaesthetic effect:--
Thiobarbiturates and some ultra short acting oxybarbiturates produce anaesthesia on Intravenous administration.
d). Anticonvulsant effect:--
Barbiturates like phenobarbitone which has a phenyl group at the 5th carbon atom, have an anticonvulsant effect.
e). Respiration:----
Respiration is not affected at sedative or Hypnotic doses. A large amount administered intravenously may produce death due to central respiratory paralysis.
2). Gastrointestinal tract:---
Intestinal motility is not affected at a standard dose, but gastric secretion may be depressed.
3). Uterus:----
Force and frequency of uterine contractions are depressed at toxic dose.
4). Kidney:---
No effect at standard dose, but anaesthetic dose decreases urinary output due to decrease in glomerular filtration and release of ADH.
5). Liver:---
No effect vat average dose, but the anesthetic dose may produce hepatic dysfunction.
♠ HOW THE DRUGS ABSORPTION, FATE AND EXCRETION:---
Oral and parental routes can administer barbiturate. They are distributed in all tissue and fluids. They Cross placental barrier and also are excreted in milk. They are cheify metabolized in the Liver and to a small extent in the Kidney and brain. Excretion is through urine both in free form and glucuronic acid conjugate.
•Adverse reaction:---
1) intolerance like nausea, headache, and diarrhea.
2) Foetal respiratory depression vif administered during labor.
3) Drug automatism due to repeatedly taking the drug oeing to forgetfulness.
4). Depends and withdrawl symptoms.
• THERAPEUTIC USE :---
1) Sedation in case of anxiety or tension.
2) Hypnosis to relieve insomnia.
3) Acticonvulsant effect in case of tetanus or status epileptic.
4). Potentiation of analgesics like salicylate.
♠ BENZODIAZEPINES :---
Diazepam b, nitrazepam and flurazepam are the important Benzodiazepines. Diazepam is the commonly used drugs.
The Benzodiazepines have.
1) anxiolytic.
2) Hypnotic
3) anti - convulsant
4) muscle relaxant effect.
All the Benzodiazepines have a Hypnotic effect. They produce less unconsciousness and respiratory depression. So these compunds are relatively non - toxic.
♠ WHAT IS NEWER NON - BENZODIAZEPINES:----
a) Zopiclone:-
It is non-Benzodiazepines sedative. It is a cyclopyrrolone derivative. It shorten sleep latency and increases total sleep time. It does not affect REM sleep, and also there is no hangover. Tolerance or rebound insomnia does not occur.
b). ZOLPIDEM:---
It is a imidazopyridine derivative. It decreases sleep latency and increases sleep duration. It has a weak anticonvulsant effect.
• ADVANTAGE:--+
1) NO tolerance or physical depends
2). Low abuse potential.
3) no rebound insomnia
4) Safety with overdose.
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