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MRCPsych – Psychopharmacology: Questions/Answers
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MRCPsych – Psychopharmacology: Questions/Answers
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MRCPsych – Psychopharmacology: Questions/AnswersLofexidine Right Ans - Lofexidine is an alpha 2 agonist which acts at the
autoreceptor.
Lofexidine stimulates the alpha 2 autoreceptors, thus stopping the release of
noradrenaline into the synapse.
When the presynaptic autoreceptors are stimulated, they generally stop the
release of the particular neurotransmitter. Thus they act as a brake.
The antagonists of autoreceptors increase the release of the neurotransmitter.
In the case of serotonin, 5HT1B are autoreceptors. Some alpha 2 receptors are
found on serotonergic neurones and control the release of 5HT; these alpha 2
receptors are called heteroreceptors.
Which of the following is NOT a reuptake inhibitor?
A. Cocaine
B. Sertraline
C. Clomipramine
D. Bupropion
E. Buspirone Right Ans - E. Buspirone is a partial agonist at 5-HT1A
autoreceptors and can influence the firing of
serotonergic (5-HT) neurones.
Cocaine is a dopamine reuptake inhibitor. Bupropion inhibits reuptake of both
dopamine and noradrenaline.
Antidepressants also block this
Class of drugs for antipsychotics Right Ans - Benzisoxazole = risperidone
Dibenzothiazepine = quetiapine
Dibenzodiazepines = clozapine
Thienobenzodiazepine = olanzapine
Substituted benzamides = Sulpiride and amisulpiride
Phenothzine = chlorpromazine
Butyrophenone = Haloperidol
,Acamprosate Right Ans - Acamprosate is used to treat alcohol dependence.
It has a structure similar to GABA and it is thought to act via glutamate
receptor mechanism.
Zopiclone Right Ans - Zopiclone is not a benzodiazepine. It is a hypnotic
classed with other 'Z drugs'; Z drugs are non benzodiazepines which act on
the GABA complex but at a slightly different site than benzodiazepines
Clozapine
anticholinergic S.E Right Ans - Clozapine causes anticholinergic effects by
blocking muscarinic (M3) receptors. This can
cause side-effects such as dry mouth, constipation, loss of accommodation,
and urinary retention.
Constipation is a side-effect in around 15% of patients taking clozapine, and,
in most, simple
advice about diet and fluid intake is sufficient.
More significant ileus is an uncommon but
potentially more serious side-effect. It may particularly be associated with
bowel surgery. It could potentially be fatal.
Which route is most liable for first-pass metabolism?
Pharmacology Right Ans - Oral
Orally administered drugs reach the liver via the portal circulation. If hepatic
metabolism is extensive, a large amount of drug will be removed during this
first passage through the liver.
Thus, even if a drug is extensively absorbed, first pass removal will reduce its
systemic availability.
So, drugs administered parenterally may need lower dosage compared to the
same compound
taken orally. Apart from the liver, first pass metabolism also takes place in gut
mucosa, muscle
tissue, and lung parenchyma, albeit to a smaller extent.
Non adherence in schizophrenia Right Ans - Up to 40-50%
, Steady state in Lithium Right Ans - The time taken for a drug to reach the
steady state is the function of its half-life. If the drug is given regularly within
its half-life, it will reach a steady state in the plasma in about four to five half-
lives.
In this case, Lithium has a half-life of nearly 24 hours. So if we give lithium
once daily for 4 days, it would have reached a steady state, and a blood taken
on the 4th or 5th morning 12 hours after the last dose will give the trough
lithium level, which will be an estimateof the plasma level of lithium.
Hyponatreamia and antidepressants Right Ans - Hyponatraemia has a well-
known association with the use of antidepressants, especially SSRIs. Elderly
people and those medically frail are worst affected. Hyponatraemia can also
confuse the picture of depression by inducing lethargy and fatigue. T
Other causes of hyponatreamia:
Carbamazepine is also associated with SIADH and hyponatraemia. Lithium
causes nephrogenic diabetes insipidus and sodium levels are either
normal or marginally high as a result. Antipsychotics are also reported to be
associated with hyponatraemia, although SSRIs are more likely to be
associated with this phenomenon.
Nocebo effect Right Ans - Placebos can also have adverse effects. Some
patients will not tolerate placebos despite the fact that they are inert, and
suffer from adverse effects (called the nocebo phenomenon).
Predisposing factors for a nocebo response include expectations of adverse
effects at the onset of treatment, conditioning, wherein the patient learns from
prior experiences to associate medication taking with certain somatic
symptoms, predisposition due to gender (women complain more),
neuroticism, hypochondriasis, a tendency to somatize, coexistent emotional
disturbances, and
situational and contextual factors that alter expectations or result in aversive
conditioning
Flumazenil Right Ans - Flumazenil is an antagonist of benzodiazepine
receptors at the GABAA complex. It is used
to reverse sedative effects of benzodiazepines used in anaesthesia and in
management of
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