Pharmadynamics

Question 1

Which of the following medications has been found to be effective in patients with premature ejaculation?

Select one:
1. Flunarizine
2. Fluoxetine
3. Flupentixol
4. Fluphenazine
5. Trifluoperazine

Answer 1

Fluoxetine

Due to the inhibitory effects of serotonin on the central ejaculatory reflex, selective serotonin reuptake inhibitors (SSRIs) are useful in the treatment of Premature Ejaculation. These inhibitors have been shown to delay ejaculation in multiple placebo-controlled randomized studies (Biri, et al., 1998; Haensel, Klem, Hop, Slob, 1998; Kara et al.,, 1996; Kim and Soo. 1998; Waldinger , Hengeveld, Zwinderman, Olivier, 1994, 1997, 1998) and is the most common class of medications used to treat PE currently.

Question 2

Drug that is comparatively safe as an adjunctive to MAOI in treating depression is

Select one:
1. Amitriptyline
2. Clomipramine
3. Fluoxetine
4. Lithium
5. Paroxetine

Answer 2

Amitriptyline

MAOIs potentiate the actions of TCAs, which may provide an explanation for the use of such a combination in the treatment of therapy-resistant depression. There is evidence to suggest that a combination of an MAOI with clomipramine is more likely to produce serious adverse effects than occurs with other TCAs.

Question 3

Buspirone acts on

Select one:
1. GABA-b receptor complex
2. 5HT2a receptor
3. 5HT1a and 5HT2a receptor
4. 5HT1a receptor
5. GABA-a receptor complex

Answer 3

5HT1a receptor

Buspirone acts on 5HT1-a receptors. It is a partial agonist at post-synaptic 5HT1-a receptors and a full agonist at pre-synaptic 5HT1-a receptors.

Question 4

A patient on mirtazapine treatment develops rapidly spreading bacterial infection. Which of the following must be immediately checked?

Select one:
1. Liver function
2. Differential count
3. Renal function
4. CSF profile
5. Blood glucose

Answer 4

Differential count

Severe neutropenia, defined as less than 0.5 x 10^9/L mature neutrophil cells, is a potentially life-threatening side effect of mirtazapine, occurring with a risk of up to 1 in 1,000 instances.

Question 5

Which one among the following has high D2/high 5HT2 activity?

Select one:
1. Clozapine
2. Quetiapine
3. Risperidone
4. Haloperidol
5. Amisulpride

Answer 5

Risperidone

Haloperidol has a High D2/low 5HT2 activity. High D2/high 5HT2 activity is characteristic of atypicals such as olanzapine, risperidone and also loxapine. Low D2/high 5HT2 is specific to clozapine while some argue that quetiapine has a lowD2/low 5HT2 activity.

Question 6

Weight gain caused by clozapine is possibly related to

Select one:
1. Alpha-2 antagonistic activity
2. 5HT1-a receptor antagonistic activity
3. 5HT2-a receptor antagonistic activity
4. 5HT2-c receptor antagonistic activity
5. 5HT3 receptor antagonistic activity

Answer 6

5HT2-c receptor antagonistic activity

The mechanism by which weight gain occurs during treatment with antipsychotics is poorly understood, but
the broader receptor affinities of the agents and their antagonism of histamine H1 and serotonin 5-HT2C
receptors have been implicated.

Question 7

The enzyme/s that metabolise/s most of the body dopamine:

Select one:
1. MAO-A and COMT
2. COMT only
3. MAO-A and MAO-B
4. MAO-B and COMT
5. MAO-A and Tyrosine hydroxylase

Answer 7

MAO-B and COMT

Dopamine is metabolized in the liver, kidney, and plasma by MAO and COMT. Therefore, inhibition of one or both of these enzymes would decrease dopamine metabolism and result in increased levels of dopamine in the brain.

Question 8

Mechanism of action of acamprosate is

Select one:
1. Opioid antagonism
2. Glutamate antagonism
3. Inhibits alcohol dehydrogenase
4. Opioid agonism
5. Inhibits aldehyde dehydrogenase

Answer 8

Glutamate antagonism

Acamprosate’s mechanism is not well understood but is thought to involve interference with excitatory amino acids such as glutamate that may be involved in alcoholic relapse.

Question 9

Which of the following antidementia drugs acts directly on nicotine receptors?

Select one:
1. Donepezil
2. Tacrine
3. Rivastigmine
4. Galantamine
5. Memantine

Answer 9

Galantamine

Galantamine, unlike the other anticholinesterases in clinical use, is derived from the alkaloids from the daffodil and snowdrop family. It is a reversible, competitive inhibitor of acetylcholinesterase with some
inhibitory action on butyrylcholinesterase. It is also an agonist at nicotinic receptor sites. Although a clinically effective drug, galantamine frequently causes gastrointestinal side effects.

Question 10

Which drug acts as a full agonist at Mu receptor and has a long half-life?

Select one:
1. Acamprosate
2. Buspirone
3. Methadone
4. Buprenorphine
5. Disulfiram

Answer 10

Methadone

Methadone is a full mu- opioid agonist. Its half-life is approximately 24 hours with regular use.

Question 11

The pharmacological activity of benzodiazepines depends on its action on which of the following receptors?

Select one:
1. Beta Adrenergic receptor complex
2. GABA-a and GABA-b receptor complex
3. 5HT1-A receptor complex
4. GABA-b receptor complex
5. GABA-a receptor complex

Answer 11

GABA-a receptor complex

Benzodiazepines act on GABA-a receptor complex and potentiates GABAergic function.

Question 12

Which of the following is a noradrenaline reuptake inhibitor?

Select one:
1. Risperidone
2. Reboxetine
3. Agomelatine
4. Fluoxetine
5. Paroxetine

Answer 12

Reboxetine

Reboxetine, the first selective norepinephrine reuptake inhibitor used in the treatment of depression, mainly acts by binding to the norepinephrine transporter and blocking the reuptake of extracellular norepinephrine.

Question 13

Which of the following is a 5HT1A partial agonist?

Select one:
1. Buspirone
2. Pramipexole
3. Amisulpride
4. Risperidone
5. Aripiprazole

Answer 13

Buspirone

Buspirone is an azaspirodecanedione, a non-benzodiazepine anxiolytic. Buspirone’s mechanism of action is related to 5HT partial agonism.

Question 14

Which of the following street drugs is called a dissociative anaesthetic?

Select one:
1. Ketamine
2. Cannabis
3. Heroin
4. LSD
5. Cocaine

Answer 14

Ketamine

Ketamine is used as a veterinary anaesthesia and produces a state of dissociative anaesthesia (not same as
psychological dissociation).

Question 15

How much Zuclopenthixol depot is equivalent to 50mg of haloperidol given every four weeks?

Select one:
1. 200mg every 2-4 weeks
2. 20 mg every 2-4 weeks
3. 20mg every 3 weeks
4. 100mg every 2-4 weeks
5. 400mg every 2 weeks

Answer 15

200mg every 2-4 weeks

Using antipsychotic depot conversion chart from POMH (Prescribing Observatory for Mental Health), 200mg / 2 weeks or 400mg/4 weeks of zuclopentixol depot is equivalent to 50mg of haloperidol depot every 4 weeks.

Question 16

Disulfiram acts on

Select one:
1. Sigma receptors
2. Alcohol dehydrogenase
3. Glutamate dehydrogenase
4. Aldehyde dehydrogenase
5. Nicotinic cholinergic system

Answer 16

Aldehyde dehydrogenase

In usual doses, disulfiram acts via inhibition of acetaldehyde dehydrogenase that produces deterrent effects when alcohol is consumed (flush reaction).

Question 17

The endocrine effects of neuroleptics would include all except

Select one:
1. Gynaecomastia
2. Primary amenorrhoea
3. Weight gain
4. Lactorrhoea
5. Impotence

Answer 17

Primary amenorrhoea

The endocrine effects are probably largely due to elevated prolactin, whose release is normally inhibited by dopamine. The endocrine effects would include secondary amenorrhoea and not primary amenorrhoea.

Question 18

Which of the following drugs is not suitable for treating acute mania?

Select one:
1. Topiramate
2. Lithium
3. Carbamazepine
4. Olanzapine
5. Valproate

Answer 18

Topiramate

Though initial data from open trials suggested that topiramate may possess antimanic properties; this has not been borne out by later more rigorous trials.

Question 19

The drug alprazolam acts on

Select one:
1. NMDA receptors
2. GABA
3. D1 receptors
4. Histaminergic receptors
5. M1 muscarinic receptors

Answer 19

GABA

Alprazolam is a benzodiazepine; it acts via GABA mechanisms.

Question 20

Which of the following increases the risk of withdrawal reactions to therapeutic drugs?

Select one:
1. The drug having anticholinergic properties
2. Taking the drug after food
3. Having multiple active metabolites with slow clearance
4. Slow withdrawal of the drug
5. Drugs being a partial agonist instead of full agonist.

Answer 20

The drug having anticholinergic properties

Paroxetine has anticholinergic properties; withdrawal causes cholinergic rebound symptoms.

Question 21

Which of the following has atypical antipsychotic activity?

Select one:
1. Fluphenazine
2. Promazine
3. Chlorpromazine
4. Amoxapine
5. Amisulpiride

Answer 21

Amisulpiride

Amisulpride has atypical antipsychotic activity as it produces very low EPSEs and is more D2/3 selective compared to other typicals. But it does not have 5HT2A blockade like other newer atypicals.

Question 22

The mechanism of action of varenicline tartrate is

Select one:
1. Nicotinic antagonist
2. Partial muscarinic agonism
3. Inhibition of nitric oxide synthesis
4. Phosphodiesterase inhibition
5. Partial nicotinic agonism

Answer 22

Partial nicotinic agonism

Varenicline is an a4ß2 nicotinic acetylcholine receptor partial agonist that relieves symptoms of nicotine withdrawal and cigarette craving through its agonist actions while blocking the reinforcing effects of continued nicotine use through an antagonist action.

Question 23

The mechanism of action for sodium valproate

Select one:
1. Dopamine stabilisation
2. NMDA antagonism
3. Benzodiazepine antagonism
4. GABA potentiation
5. Membrane stabilising

Answer 23

GABA potentiation

Valproate acts at sodium channels, at several important steps in GABA metabolism leading to GABA potentiation, and on the activity of histone deacetylase (which influences gene transcription).

Question 24

Which of the following statements best describes the receptor profile of trazodone?

Select one:
1. It is a serotonin antagonist
2. It is a mixed serotonin antagonist/agonist.
3. It is a serotonin, dopamine and norepinephrine antagonist
4. It is a serotonin, dopamine and norepinephrine agonist
5. It is a serotonin agonist

Answer 24

It is a mixed serotonin antagonist/agonist

Trazodone is a multifunctional drug: it is a hypnotic at low doses and an antidepressant at high doses due to the manner in which different multifunctional binding properties apply at different doses. Trazodone’s most potent binding property is 5-HT2A antagonism. Its ability to block Serotonin reuptake transporters (SERT) is 100 fold less potent than its ability to block 5- HT2A receptors. Trazadone is categorized as ‘serotonin antagonist-reuptake inhibitor’. At lower doses, it acts as 5HT2A antagonist; though at higher doses it acts as SERT blocker.

Question 25

Which of the following actions can cause anorgasmia?

Select one:
1. Beta agonism
2. GABA-A agonism
3. Alpha 1 agonism
4. Antihistaminergic property
5. Alpha 1 antagonism

Answer 25

Alpha 1 antagonism

Alpha 1 antagonism, 5HT2A/2C stimulation (delayed ejaculation in SSRIs) can cause anorgasmia. Retrograde ejaculation due to Alpha 1 block, anticholinergic and antihistaminic effects.

Question 26

Endogenous substrates for monoamine oxidase (MAO) isoenzymes include

Select one:
1. Tyramine, acetylcholine, and dopamine.
2. Acetylcholine, dopamine and epinephrine.
3. Epinephrine, dopamine, and serotonin.
4. Tyramine, serotonin, and histamine.
5. Histamine, acetylcholine, and serotonin.

Answer 26

Epinephrine, dopamine, and serotonin.

Endogenous monoamines serotonin, dopamine and norepinephrine, are broken down by MAO enzymes. MAO-A is more selective for serotonin while MAO-B is more so for dopamine.

Question 27

Drug X produces improvement in depression when given at a dose of 10mg. Drug Y which acts via the same mechanism as X produces the same improvement when given at a dose of 20mg. When X and Y are given together Y binds to more receptors in a quicker and stronger fashion than X. Which of the following is true?

Select one:
1. Y has lesser affinity then X
2. X is less potent than Y
3. X and Y are equally efficacious
4. X and Y have equal potency but different affinity
5. X and Y have equal affinity but different potency

Answer 27

X and Y are equally efficacious

Efficacy refers to how well the drug produces the expected response i.e. the maximum clinical response produced by a drug (‘productivity’). Efficacy depends on affinity, potency, duration of receptor action in some cases and kinetic properties such as half life, among other factors.

Question 28

Which one among the following has a stimulant effect?

Select one:
1. Dothiepin
2. Lofepramine
3. Imipramine
4. Amitryptyline
5. Desipramine

Answer 28

Desipramine

Desipramine has relative selectivity for noradrenaline re-uptake and has a stimulant effect.

Question 29

Which one of the following has antiepileptic activity?

Select one:
1. Fluoxetine
2. Buspirone
3. Buspirone
4. Bupropion
5. Gabapentin

Answer 29

Gabapentin

Gabapentin has antiepileptic property.

Question 30

Which of the following types of drug molecules mimic endogenous chemical transmission?

Select one:
1. Antagonists
2. Agonists
3. Partial agonists
4. Non-competitive antagonists
5. Irreversible enzyme inducers

Answer 30

Agonists

Most antagonist drugs are competitive in nature, are displaced from their binding site by agonists so that at high doses the agonist can still exert maximum effect and cause a shift to the right in the dose-response curve for the agonist. Agonists are drugs that mimic endogenous transmission. A partial agonist can partially
antagonise the effect of full agonists. Buprenorphine, buspirone and aripiprazole are all partial agonists.

Question 31

The mechanism of action of cyproheptadine is

Select one:
1. Histamine H1 receptor blockade
2. Serotonin 5HT3 receptor blockade
3. Serotonin 5HT2 receptor stimulation
4. Histamine H2 receptor blockade
5. Histamine H1 receptor stimulation

Answer 31

Histamine H1 receptor blockade

Anorgasmia related to SSRI use may be treated by cyproheptadine one to two hours before sexual activity. Cyproheptadine is a sedating antihistamine with antimuscarinic,5HT2A serotonin-antagonist and calcium-channel blocking properties. It competes for H1-receptor sites on effector cells in the GIT, blood
vessels and respiratory tract.

Question 32

The chronic administration of tricyclics results in

Select one:
1. Upregulation of beta-adrenergic receptors
2. Down regulation of beta and alpha adrenergic receptors
3. Up-regulation of alpha-adrenergic receptors
4. Downregulation of alpha-adrenergic receptors
5. Downregulation of beta-adrenergic receptors

Answer 32

Downregulation of beta-adrenergic receptors

It has been consistently reported that chronic administration (2 to 4 weeks of treatment) of antidepressant drugs causes a downregulation of beta receptors in rats. However, such effects are not observed after acute or single administration of these drugs. Since most of the antidepressant drugs tested thus far produce such effects, it has been suggested that downregulation or decreased responsiveness of beta-adrenergic receptors may be related to the therapeutic effects manifested by antidepressant drugs. This is yet to be clarified.

Question 33

Excitotoxicity that is secondary to glutamatergic overstimulation results in neuronal damage. This is the basis of treating patients with neurodegenerative disorders with which of the following medications?

Select one:
1. Selegiline
2. Donepezil
3. Risperidone
4. Galantamine
5. Memantine

Answer 33

Memantine

The hypothesis that glutamate-mediated neurotoxicity is involved in the pathogenesis of AD is increasingly
being favoured; Glutamate receptors are overactive, and N-methyl-D-aspartate (NMDA) receptor antagonists have therapeutic potential for the treatment of AD and other neurological disorders. Memantine is a non-competitive NMDA antagonist that is considered a neuroprotective drug.

Question 34

Which one among the following is a weak inhibitor of cytochrome P450?

Select one:
1. Both 1 and 2
2. Fluvoxamine
3. Citalopram
4. Paroxetine
5. Fluoxetine

Answer 34

Citalopram

Citalopram and Escitalopram do not produce cytochrome P 450 inhibition. Fluoxetine, Fluvoxamine and Paroxetine are potent inhibitors of several hepatic cytochrome enzymes. Sertraline is safer, while citalopram is the safest. Citalopram is a weak inhibitor of 2D6.

Question 35

Which one of the following is a pure D2 antagonist?

Select one:
1. Aripiprazole
2. Clozapine
3. Risperidone
4. Amisulpride
5. Sulpiride

Answer 35

Sulpiride

Sulpiride is a pure D2 antagonist. Whereas, Amisulpride is a D2/D3 antagonist. At low doses blocks autoreceptors thus increasing the synaptic dopamine levels and thought to be how it improves negative symptoms. In the limbic region, blockade of postsynaptic D2/D3 receptors reduces positive symptoms.

Question 36

A patient with Parkinson’s disease experiences visual hallucinations on levodopa/carbidopa therapy. The most appropriate intervention would be to initiate treatment with which of the following medications?

Select one:
1. Aripiprazole
2. Amisulpride
3. Olanzapine
4. Risperidone
5. Quetiapine

Answer 36

Quetiapine

Atypical antipsychotic, especially quetiapine, have a reduced likelihood of causing adverse drug-induced parkinsonism and therefore a possible role in treating psychotic symptoms in patients with Parkinson’s, including the hallucinations induced by levodopa/ carbidopa.

Question 37

Mechanism of action of buprenorphine is via partial agonism at

Select one:
1. ß-opioid receptors
2. µ-opioid receptors
3. Adrenergic receptors
4. k-opioid receptors
5. Cholinergic receptors

Answer 37

µ-opioid receptors

Buprenorphine. A partial opiate agonist at mu-receptors is available in sublingual form as an alternative to methadone for agonist maintenance treatment of opioid dependence.

Question 38

Which one of the following has been postulated as the pharmacological basis of clozapine related hypersalivation?

Select one:
1. Reduced cholinesterase activity
2. Activation of the swallowing reflex.
3. Muscarinic M-4 antagonism
4. Adrenergic alpha-2 stimulation
5. Muscarinic M-4 agonism

Answer 38

Muscarinic M-4 agonism

Clozapine is well known to be associated with hypersalivation (drooling particularly at night). This seems to be problematic in the early stages of treatment and is probably dose-related. M4 agonism may be an underlying mechanism though this is not clear. Loss of swallowing reflex may also contribute.

Question 39

Which of the following has no evidence-based support when prescribing antidementia drug donepezil?

Select one:
1. Reduces caregiver burden
2. Improves the amount of daily activities in some patients
3. Improves neuropsychiatric symptoms
4. Reduces the progression of cognitive decline
5. Reduces time to institutionalisation

Answer 39

Reduces time to institutionalisation

There is strong evidence that donepezil has efficacy against the three major domains of Alzheimer’s disease symptoms, namely functional ability, behaviour, and cognition. The strongest evidence is for improvement or less deterioration in global outcomes and cognition in the short to medium term. There is limited evidence that improved global outcomes are maintained in the long term and clear evidence to support long-term maintenance of cognitive benefits. Also, donepezil appears to maintain function in the long term, and there is some level 1 and two evidence of improved or limited deterioration in behaviour or mood in the short to medium term. Despite donepezil’s effects on major symptoms of Alzheimer’s disease, its impact on patients’ quality of life has not been consistently demonstrated, perhaps reflecting the difficulty of assessing this aspect in this patient population. Donepezil may also lessen caregiver burden. There is limited and conflicting weak evidence that long-term donepezil treatment delays time to institutionalization.

Question 40

Which of the following is a partial D2 agonist?

Select one:
1. Risperidone
2. Amisulpride
3. Pramipexole
4. Aripiprazole
5. Buspirone

Answer 40

Aripiprazole

Aripiprazole is a dopamine D2 receptor partial agonist with partial agonist activity at serotonin 5HT1A receptors and antagonist activity at 5HT2A receptors.

Question 41

A new drug A is a non-competitive antagonist at NMDA receptors. If availability of glutamate at the receptor sites is increased experimentally after administering drug A, which of the following can happen?

Select one:
1. Effect of drug A is partially reversed
2. Glutamate levels decrease
3. No change takes place
4. Effect of drug A is reversed fully
5. Effect of drug A increases

Answer 41

Effect of drug A is partially reversed

Non-competitive antagonists alter the receptor site in some way so the effects can be reversed only partially by increasing the dose of the agonist drug. Non-competitive antagonism reduces both the potency and the efficacy of agonists.

Question 42

A 85-year-old lady with a history of cerebrovascular disease, atrial fibrillation, and prior myocardial infarction presents with moderately severe agitated depression with features of self-neglect. She is taking warfarin, lisinopril, and has been on a maximum dose of venlafaxine for last four weeks with moderate effect. The most appropriate intervention to manage the depression is

Select one:
1. Add a benzodiazepine
2. Prescribe trazodone
3. Add mirtazapine
4. Trial of sertraline after stopping venlafaxine
5. Electro convulsive therapy

Answer 42

Add mirtazapine

Mirtazapine works well in combination with venlafaxine; it will be the ideal choice in the above scenario.

Question 43

Tyramine gains neuronal access and releases stored catecholamines via which of the following routes?

Select one:
1. GABA
2. NMDA channel
3. Calcium channels
4. Sodium channels
5. Catecholamines reuptake channels

Answer 43

Catecholamines reuptake channels

As with most indirect sympathomimetics, tyramine enters the presynaptic neuron through amine uptake pumps - the channels that are blocked by antidepressants such as TCAs.

Question 44

The therapeutic effects of conventional antipsychotics is mainly due to

Select one:
1. Blockade of dopamine-2 receptors in the mesocortical pathway
2. Blockade of alpha-1 receptors
3. Blockade of dopamine-2 receptors in the nigrostriatal pathway
4. Blockade of dopamine-2 receptors in the tuberoinfundibular pathway
5. Blockade of dopamine-2 receptors in the mesolimbic pathway

Answer 44

Blockade of dopamine-2 receptors in the mesolimbic pathway.

Blockade of dopamine-2 receptors in the mesolimbic pathway leads to the therapeutic effects. Blockade of dopamine-2 receptors in the mesocortical pathway leads to production or worsening of negative symptoms. Blockade of dopamine-2 receptors in the nigrostriatal pathway leads to EPSEs. Blockade of dopamine-2
receptors in the tuberoinfundibular pathway leads features of hyperprolactinaemia such as galactorrhoea,
sexual dysfunction, gynaecomastia, infertility, amenorrhoea, and possibly accelerated osteoporosis. Blockade of alpha-1 receptors leads to sedation, dizziness, orthostatic hypotension.

Question 45

Which one among the following is the least sedative of tricyclic antidepressants?

Select one:
1. Dothiepin
2. Nortriptyline
3. Amitryptyline
4. Lofepramine
5. Imipramine

Answer 45

Nortriptyline

Amitryptyline and dothiepin are more sedative, with trimipramine being the most sedative, Imipramine and Lofepramine are less sedative, and Nortriptyline is the least sedative.

Question 46

A 27-year-old man who is taking mirtazapine for generalized anxiety disorder and major depression
experiences significant sedation at a dosage of 7.5 mg/day. Which neurotransmitter receptor is most likely
being affected?

Select one:
1. Nictonic receptors
2. Histamine Type 1 receptors
3. 5HT Type 2 receptors
4. Muscarinic type 1 receptors
5. 5HT type 3 receptors

Answer 46

5HT Type 2 receptors

Blockade of 5HT2 receptors by mirtazapine helps improving the quality of sleep in depressed patients.

Question 47

Which of the following groups of medications are associated with bruxism more often than the others listed?

Select one:
1. Stimulants
2. Antidementia drugs
3. Antidepressants
4. Antipsychotics
5. Benzodiazepines

Answer 47

Stimulants

Teeth grinding in children is otherwise known as bruxism. It is associated with ADHD especially when stimulants are sued for its treatment.

Question 48

Poor response to lithium prophylaxis is predicted by

Select one:
1. classic mania
2. family loading of bipolar spectrum disorders
3. rapid cycling
4. secondary mania
5. obsessional symptoms

Answer 48

Rapid cycling

The phenotype of lithium responders tend to differ from that of other mood stabilisers. Patients with episodic pattern, no comorbidity (especially no panic attacks and substance abuse), significantly higher familial risk of bipolar disorder and absence of rapid cycling pattern are some of the indicators for therapeutic response to lithium.

Question 49

The mechanism of action of barbiturates is by

Select one:
1. Increasing the frequency of chloride channels opening
2. Increasing the duration of chloride channel opening
3. Closing down the potassium channels
4. Increasing the number of chloride channels
5. Closing down the sodium channels

Answer 49

Increasing the duration of chloride channel opening

Barbiturates act on GABA receptors and serve to increase the duration of chloride channel opening.

Question 50

Receptor blockade in which dopaminergic pathway results in increased prolactin levels in the body?

Select one:
1. Mesocortical pathway
2. Nigrostriatal pathway
3. Mesolimbic pathway
4. Ultra short ganglionic pathway
5. Tuburoinfundibular pathway.

Answer 50

Tuburoinfundibular pathway.

Blockade of dopamine-2 receptors in the mesolimbic pathway leads to the therapeutic effects. Blockade of dopamine-2 receptors in the mesocortical pathway leads to production or worsening of negative symptoms. Blockade of dopamine-2 receptors in the nigrostriatal pathway leads to EPSEs. Blockade of dopamine-2
receptors in the tuberoinfundibular pathway leads features of hyperprolactinaemia such as galactorrhoea,
sexual dysfunction, gynaecomastia, infertility, amenorrhoea, and possibly accelerated osteoporosis.