4A - Tranquillizers Flashcards
Minor tranquilizers;
Also called “antianxiety agents”
Useful to calm anxious patients before surgery
For people who have neuroses and fear some of life’s “normal” situations
For insomniacs who are so tense that they cannot function or sleep normally
Most common
Xanax, Librium, Valium, Ativan-for daytime use
As sleeping aids: Restoril, Halcion
GABA
Gamma Amino Butyric Acid
Inhibits neurotransmission in the brain
Blocks the arousal of “higher” brain centres
GABA receptor is a macromolecular complex
BDA’s enhace GABA activity
BDA’s (Benzodiazepines) make the GABA receptor site more efficient
Open up the Cl- channel
Results in increased chloride ion concentration in the post synaptic neuron
Makes this neuron “less excitable” IE. Decreased excitation of many nerve systems, reduced anxiety, diminished alertness and an increase in the threshold of convulsion
Other minor tranquilizers
Equanil, Miltown; mechanism of action not known completely
- NO LONGER SOLD IN CANADA - RISKS OUTWEIGH BENEFIT
Problems with Halcion
Largely ineffective after 2 weeks of continued use
Not for use if pregnant –it is teratogenic!
Banned in the UK
Adverse effects: amnesia, suicidal behaviour, agitation,
Also “rebound insomnia” can occur with drugs having short half lives
- NEVER COMBINE WITH ALCOHOL
Comparison to barbiturates
Barbiturates are older drugs used as “minor tranquilizers”
But, major abuse potential, since these drugs depress respiration
BDA’s are “safer’ since they do not significantly depress respiration
BUT»>This is NOT true if BDA’s are combined with alcohol!
Popular sleep inducing drugs
Ambien and Lunesta are popular
BDA Withdrawal symptoms
Anxiety, restlessness, tremors, nausea, cramps,……
Also paranoia and disorganized irrational thinking
Psychopharmacology of Benzodiazepines
Benzodiazepine (BDA) receptors are located primarily in the brain, hence these drugs have no effect on the heart or skeletal muscles
“pharmaceutical pollution”
When a person takes a drug, the entire dose does not get absorbed by the body
Some of the original drug, along with its metabolites, gets excreted
Ends up in wastewater and can enter the natural water supply
Major tranquilizers
Include antipsychotics, drugs for manic depression, treating acute alcoholism or geriatric agitation
Chlorpromazine & Dosage
Used as an anesthetic booster in intravenous doses of 50-100mg on surgery patients
Found to be “the best drug to date” in calming and reducing shock
75-100mg /day
Many inhumane methods of coping with psychotic behaviour (Isolation, shock therapy, lobotomies) etc were replaced by chlorpromazine treatment
How do major tranquilizers work?
Evidence supports antipsychotic agents acting on the cortex of the brain, at the cortical synapses, where dopamine is the neurotransmitter
Phenothiazines such as chlorpromazine block the dopamine receptors thus preventing the stimulating action of dopamine
Schizophrenia is deemed to be caused by abnormally high amounts of dopamine in the brain, hence this mode of action is consistent with the action of antipsychotic drugs to reduce the symptoms that schizophrenics experience
Some Things to note about antipsychotic drugs
Antipsychotic effect is slow to develop-often need several weeks before results are noticed
Similarly, after therapy is ceased, some amounts of these drugs remains in the body, due to the high lipophilicity (fat soluble nature) of these substances
