1. Neuroleptics Flashcards
(18 cards)
What groups of drugs neuroleptics include?
Phenothiazine derivatives + butiriphenones
What drugs belong to phenothiazine derivatives?
- Acepromazine
- Chlorpromazine
- Propionylpromazine
Mechanism of action of phenothiazines (receptors)
Antagonist of:
* Dopaminergic receptor (D2) -› antipsychotic, antiemetic effect
* α-adrenoreceptor -› hypotension, sedation
* muscarinic receptor (mainly side effects)
* H1 receptor -› sedation, antiemetic effect
* 5HT receptor (enhancement of other effects)
Pharmacological effects of phenothiazine derivatives:
- sedation (catalepsy-like immobilization)
- potentiation
- antiemetic effect
- inhibition of regulation of body temperature
Pharmacokinetics of phenothiazines
- Poor oral absorption
- Good tissue distribution
- Slow onset of activity
- Long duration
- 95% of plasma protein binding
- Metabolism in liver
- Excretion via urine, in metabolites
- Slow elimination from the body, long WP
Side effects of phenothiazines
- Hypotension (not for dehydrated or in shock)
- Hypothermia
- Tissue irritation, allergy, liver damage
- Penile prolapse (horses) and third eyelid prolapse (pets)
- Epilepsy
- Prolactin↑
- FSH, LH, ADH and oxytocin↓
Main usage of phenothiazines
- calming during veterinary investigation and transport
- decrease of motor activity
- premedication
Contraindications for phenothiazine derivatives:
- dehydrated animals
- shock
- epileptic animals
- pseudopregnant animals
Chlorpromazine
- frequent side effects
- tissue irritation
- paradox reaction in horses
Acepromazine
more efficacious than chlorpromazine, less side effects, better oral bioavailability
Propionylpromazine
more reliable than chlorpromazine, less side effects
Is oral absorption of phenothiazine tranquillisers good?
No. F = 0,2. Better in buccal, rectal use
Also IV, IM application
Do phenothiazines cross BBB?
Yes -> good tissue distribution
What is onset of activity for phenothiazines?
Slow onset. Long duration (10-12 hours)
Drugs belonging to butirophenones:
- AZAPERONE
- Droperidol
- Fluanisone
Mechanism of action of butirophenones:
- D2 inhibitors
- NA inhibitors
- Anticholinergic effects in CNS
- weak antagonists on alpha1 and H1 receptors
are more potent than phenothiazine derivatives, have some analgesic effects
applied only IM
Which neuroleptic drug targets swine? What group of CNS depressants?
Azaperone. Butirophenones
Used in combination with metomidate
Side effects, contraindications of butirophenons
- salivation or panting
- hypotension
- boar penile prolapse
- avoid use in cold conditions
