Pharmacology Quiz: GABAA Modulators and Receptor Effects

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80 Questions

What is the main form of vitamin B6 found in multivitamins?

Pyridoxine

Which type of drugs are antagonists of dopamine receptors and are contraindicated with l-DOPA?

Antipsychotics

What effect may pyridoxine have on the metabolism of l-DOPA?

Enhance the metabolism

Which medication depletes dopamine and is contraindicated with l-DOPA?

Reserpine

What is the recommended withdrawal period for Monoamine oxidase inhibitors (MAOIs) prior to l-DOPA administration?

2 weeks

How do anticholinergics affect gastric emptying?

Slow down gastric emptying

Which type of GABAA-mediated inhibition involves receptors with α + γ subunits?

Phasic inhibition

What is the primary mechanism of action for barbiturates at GABAA receptors?

Binding site within the channel

Which drug is contraindicated in porphyria patients or those with a family history of porphyria?

Phenobarbital

What is the medical emergency characterized by prolonged seizures or multiple seizures in succession without recovery of consciousness?

Status epilepticus

What is the purpose of antiepileptic drugs?

Inhibiting abnormal neuronal discharges

Which drug class has an allosteric binding site that potentiates Cl- flow and a higher therapeutic index?

Benzodiazepines

Which type of inhibition captures GABA that has diffused away from the synapse?

Tonic inhibition

What type of effect do barbiturates have on GABAA receptors?

Increase the conductance of GABAA to chloride ions

What is the mechanism of action of flumazenil?

Antagonist to benzodiazepine action

Which hormone promotes sleep and is inhibited by light?

Melatonin

What is the role of sevorexant?

Inhibits orexin receptors

Which drug class induces the rate-limiting step of heme biosynthesis?

Barbiturates

What is the primary role of carbidopa when co-administered with l-dopa for the treatment of Parkinson's disease?

Inhibiting the degradation of l-dopa by COMT in the periphery

Which enzyme degrades l-dopa in the periphery and is inhibited by carbidopa?

COMT

What is the goal of dopamine supplementation therapy for Parkinson's disease?

Minimize 'off' time, make it as predictable as possible, and treat it with the least amount of medication

What are the primary excitatory and inhibitory neurotransmitters in the central nervous system?

Glutamate and GABA

What is the primary pharmacological target of GABA in the central nervous system?

Muscle tone and sleep

What is the main function of GABAergic neurotransmission?

Decreased responsiveness to excitatory current

Which enzyme is responsible for the synthesis of GABA from glutamate in GABAergic neurons?

Glutamic Acid Decarboxylase (GAD)

How are GABA's effects terminated in the synaptic cleft?

By uptake transporters in astrocytes and presynaptic neurons (GABA transporters, or GATs)

What role do astrocytes play in neuronal communication involving glutamate and GABA?

They degrade glutamate and recycle GABA

What is the function of benzodiazepines and barbiturates on GABAA receptors?

They enhance the inhibitory effects of GABA on neuronal activity

What triggers the release of glutamate from presynaptic terminals?

Arrival of an action potential

Which type of GABA receptors open chloride ion channels upon binding of GABA?

Ionotropic GABA receptors

Which neurotransmitter is primarily responsible for promoting repolarization at excitatory glutamatergic synapses?

Glutamate

Which antiepileptic drug inhibits voltage-dependent Na+ channels, blocks the degradation of GABA, and activates the synthesis of GABA?

Valproic acid

Which antiepileptic drug exhibits non-linear pharmacokinetics and has a relationship between dosage and plasma concentration that is not linear?

Phenytoin

What is the primary inhibitory neurotransmitter in the central nervous system (CNS)?

GABA

Which mechanism do anticonvulsants use to inhibit abnormal neuronal discharges by acting at excitatory glutamatergic synapses?

Inhibiting calcium entry

What is the primary excitatory neurotransmitter in the central nervous system (CNS)?

Glutamate

Which antiepileptic drug inhibits voltage-gated sodium channels in a voltage- and use-dependent manner?

Lamotrigine

Which type of kinetics do phenytoin exhibit with increased doses?

Zero-order kinetics

Which anticonvulsant is debated to inhibit T-type Ca2+ channels and NMDA-receptor activation?

Valproic acid

Which channels does valproic acid inhibit as one of its mechanisms of action?

T-type Ca2+ channels

What form of vitamin B6 found in multivitamins may enhance the metabolism of l-DOPA?

Pyridoxine

Which drug class, as antagonists of dopamine receptors, are contraindicated with l-DOPA?

Antipsychotics

Which enzyme depletes dopamine and is contraindicated with l-DOPA?

Dopamine decarboxylase

Which medication blocks dopamine breakdown and may exaggerate effects such as hypertensive crisis and hyperpyrexia?

Monoamine oxidase inhibitors (MAOIs)

Which drug class may slow gastric emptying?

Anticholinergics

Which enzyme is a cofactor for dopa decarboxylase and may enhance the metabolism of l-DOPA?

Kinase

Which type of GABAA-mediated inhibition involves receptors with α + δ subunits?

Tonic inhibition

What is the primary effect of barbiturates at GABAA receptors?

Increase the conductance of chloride ions

In what way do benzodiazepines affect the frequency of channel opening when only GABA is bound?

Have no effect on the frequency of channel opening

What is the primary role of antiepileptic drugs?

Inhibiting abnormal neuronal discharges

Which drug class is contraindicated in porphyria patients or those with a family history of porphyria?

Barbiturates

What is the medical emergency characterized by prolonged seizures or multiple seizures in succession without recovery of consciousness?

Status epilepticus

Which drug class has an allosteric binding site that potentiates Cl- flow and a higher therapeutic index?

Benzodiazepines

What is the primary mechanism of action for barbiturates at GABAA receptors?

Increasing GABAA conductance to chloride ions

What is the medical emergency characterized by prolonged seizures or multiple seizures in succession without recovery of consciousness?

Status epilepticus

What is the primary role of carbidopa when co-administered with l-dopa for the treatment of Parkinson's disease?

Inhibiting degradation of l-dopa in the periphery

Which drug class induces the rate-limiting step of heme biosynthesis?

Barbiturates

What effect may pyridoxine have on the metabolism of l-DOPA?

Potentiate its effects

What is the primary inhibitory neurotransmitter in the central nervous system?

GABA

Which enzyme degrades l-dopa in the periphery and is inhibited by carbidopa?

Aromatic L-amino acid decarboxylase (AAAD)

What are the primary excitatory and inhibitory neurotransmitters in the central nervous system?

Glutamate and GABA

What is the primary pharmacological target of GABA in the central nervous system?

Neuronal hyperactivity

Which drug class induces the rate-limiting step of heme biosynthesis?

Barbiturates

Which antiepileptic drug inhibits voltage-dependent Na+ channels, blocks the degradation of GABA, and activates the synthesis of GABA?

Valproic acid

Which type of receptor is an ionotropic GABA receptor?

Ligand-gated ion channel

What is the primary role of astrocytes in neuronal communication involving glutamate and GABA?

Degradation and recycling of glutamate

What is the mechanism of action for benzodiazepines and barbiturates on GABAA receptors?

Enhance GABAA receptor function

What is the primary excitatory neurotransmitter in the central nervous system (CNS)?

Glutamate

Which enzyme is responsible for the synthesis of GABA from glutamate in GABAergic neurons?

Glutamic acid decarboxylase (GAD)

What effect do barbiturates have on GABAA receptors?

Enhance GABAA receptor function

Which antiepileptic drug is known for inhibiting the degradation of GABA (GABA-T) and activating the synthesis of GABA (GAD)?

Valproic acid

Which type of neurotransmitter primarily promotes repolarization at excitatory glutamatergic synapses in the central nervous system (CNS)?

Glutamate

Which anticonvulsant drug exhibits non-linear pharmacokinetics, leading to a shift from first to zero-order kinetics with increased doses?

Phenytoin

Which neurotransmitter is primarily responsible for inhibiting abnormal neuronal discharges by limiting the depolarization of the terminal and inhibiting Ca2+ entry at excitatory glutamatergic synapses?

GABA

Which anticonvulsant is debated to inhibit T-type Ca2+ channels and NMDA-receptor activation?

Lamotrigine

Which antiepileptic drug inhibits voltage-dependent Na+ channels, blocks the degradation of GABA (GABA-T), and activates the synthesis of GABA (GAD)?

Valproic acid

Which antiepileptic drug is known for inhibiting voltage-gated sodium channels in a voltage- and use-dependent manner?

Phenytoin

Which anticonvulsant drug exhibits non-linear pharmacokinetics, leading to a shift from first order to zero order with increased doses?

Phenytoin

Which antiepileptic drug is debated to inhibit T-type Ca2+ channels and NMDA-receptor activation?

Lamotrigine

Which anticonvulsant drug is known for inhibiting voltage-gated sodium channels in a voltage- and use-dependent manner?

Phenytoin

Study Notes

  • Antiepileptic drugs, also known as anticonvulsants, are medications used to prevent seizures and inhibit abnormal neuronal discharges in people with epilepsy.

  • Epilepsy is a neurological disorder characterized by unprovoked seizures, which are caused by abnormal neuronal activity in the brain.

  • Glutamate is the primary excitatory neurotransmitter, and GABA is the primary inhibitory neurotransmitter in the central nervous system (CNS).

  • Abnormal neuronal activity and hyperexcitability in the brain can be caused by excessive release of glutamate and insufficient release of GABA.

  • Voltage-gated sodium channels are responsible for the upstroke of action potentials that propagate through neurons, which contributes to the generation of seizures.

  • Anticonvulsants can inhibit abnormal neuronal discharges by inhibiting glutamate release, slowing down the rate of recovery from inactivation of voltage-gated sodium channels or inhibiting voltage-gated sodium channels directly.

  • Phenobarbital, phenytoin, and lamotrigine are examples of anticonvulsants that inhibit voltage-gated sodium channels, while phenytoin and lamotrigine do so in a voltage- and use-dependent manner.

  • Phenytoin and fosphenytoin have non-linear pharmacokinetics, which means that their relationship between dosage and plasma concentration is not linear.

  • Phenytoin metabolism gets saturated with increased doses, leading to a shift from first to zero-order kinetics, while oral gabapentin kinetics shift from first order to zero but in the opposite direction due to the saturation of the transporter necessary for absorption.

  • Anticonvulsants can also act at excitatory glutamatergic synapses by inhibiting the release of glutamate, limiting the depolarization of the terminal, inhibiting Ca2+ entry, promoting repolarization, or inhibiting exocytosis of glutamatergic vesicles.

  • Valproic acid is an antiepileptic drug that inhibits voltage-dependent Na+ channels, blocks the degradation of GABA (GABA-T), activates the synthesis of GABA (GAD), and inhibits GABA transporters (i.e., reuptake). It is also debated to inhibit T-type Ca2+ channels and NMDA-receptor activation.

  • Antiepileptic drugs, also known as anticonvulsants, are medications used to prevent seizures and inhibit abnormal neuronal discharges in people with epilepsy.

  • Epilepsy is a neurological disorder characterized by unprovoked seizures, which are caused by abnormal neuronal activity in the brain.

  • Glutamate is the primary excitatory neurotransmitter, and GABA is the primary inhibitory neurotransmitter in the central nervous system (CNS).

  • Abnormal neuronal activity and hyperexcitability in the brain can be caused by excessive release of glutamate and insufficient release of GABA.

  • Voltage-gated sodium channels are responsible for the upstroke of action potentials that propagate through neurons, which contributes to the generation of seizures.

  • Anticonvulsants can inhibit abnormal neuronal discharges by inhibiting glutamate release, slowing down the rate of recovery from inactivation of voltage-gated sodium channels or inhibiting voltage-gated sodium channels directly.

  • Phenobarbital, phenytoin, and lamotrigine are examples of anticonvulsants that inhibit voltage-gated sodium channels, while phenytoin and lamotrigine do so in a voltage- and use-dependent manner.

  • Phenytoin and fosphenytoin have non-linear pharmacokinetics, which means that their relationship between dosage and plasma concentration is not linear.

  • Phenytoin metabolism gets saturated with increased doses, leading to a shift from first to zero-order kinetics, while oral gabapentin kinetics shift from first order to zero but in the opposite direction due to the saturation of the transporter necessary for absorption.

  • Anticonvulsants can also act at excitatory glutamatergic synapses by inhibiting the release of glutamate, limiting the depolarization of the terminal, inhibiting Ca2+ entry, promoting repolarization, or inhibiting exocytosis of glutamatergic vesicles.

  • Valproic acid is an antiepileptic drug that inhibits voltage-dependent Na+ channels, blocks the degradation of GABA (GABA-T), activates the synthesis of GABA (GAD), and inhibits GABA transporters (i.e., reuptake). It is also debated to inhibit T-type Ca2+ channels and NMDA-receptor activation.

Test your knowledge of GABAA modulators and their effects on receptors with this pharmacology quiz. Explore principles of pharmacology, including the duration of action of GABAA modulators and the effects of benzodiazepines and barbiturates on GABAA receptors.

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