Q21

What are the indications for benzodiazepine use?

  • Anxiety Disorders
  • Preoperative Medication
  • Insomnia
  • Sleep Disturbances
  • Seizure Disorders
  • Panic Disorder
  • Alcohol Withdrawal
  • Muscle Spasm
  • Induce amnesia during procedural sedation

Pass Criteria: Seizures PLUS 2 others

Explain the rationale for use of benzodiazepines in alcohol withdrawal.

  • Down-regulation of neuro-inhibitory GABA receptors in alcohol dependent individual leads to symptoms of GABA deficiency in withdrawal.
  • BZD act at a modulatory site on the the GABAA receptor to facilitate GABA binding to the GABAA receptors, enhance chloride channel opening, and overcome neuroexcitatory symptoms of GABA deficiency

Pass Criteria:

Facilitate GABA binding to the GABAA receptors

Control neuroexcitatory symptoms of alcohol withdrawal


Q22

Describe the pharmacokinetics of lithium.

  • Rapidly absorbed (except SR preparations) with peak plasma concs in 1-3hrs.  High bioavailability.
  • Not metabolised
  • Renally excreted unchanged with partial reabsorption from PT.
  • Long T ½ of 24hrs in adults
  • Steady state plasma concs not reached for 5-7 days

 Pass Criteria:

Long T ½ so steady state plasma concs not reached for days.

Renally excreted unchanged

What are the adverse effects of Lithium at therapeutic levels?

  • Short termTremor, nausea, polydypsia /polyuria, diarrhoea, weight gain.
  • Long-term:
    • Acne / psoriasis,
    • hypothyroidism,
    • nephrogenic diabetes insipidus

 Pass Criteria: Polyuria & Polydipsia OR NDI

What are the signs/symptoms of lithium toxicity?

  • GIT: Vomiting.
  • Neuro: Tremors, confusion, slurred speech, ataxia, drowsiness, blurred vision, seizures

Pass Criteria: CNS effects with at least 3 symptoms


Q23

Describe the distribution of thiopentone following an IV bolus.

  • To highly vascular tissue and rapidly crosses BBB.
  • High lipid solubility.
  • Then rapidly redistributed to body fat.

What are the potential adverse effects of thiopentone?

  • Advantages:
    • Rapid,
    • Controllable,
    • Amnesic,
    • Reduction of ICP,
    • anticonvulsant
    • Disadvantages:
      • Hypotension,
      • Venous irritant,
      • Myocardial depression,
      • minimal muscle relaxation and analgesia,
      • hepatic metabolism (vs inhalational agents)

Pass criteria: Bold


Q24

How do benzodiazepines work at the receptor level?

  • Bind to the GABA receptor at a site separate to GABA binding
  • GABA opens Chloride channels increasing the membrane potential
  • Does not directly activate the receptor but facilitates the effect of GABA on the receptor.

 

What are the clinical effects of benzodiazepines?

  • Sedation
  • Hypnosis
  • Anesthesia
  • Anticonvulsant
  • Muscle relaxation
  • Respiratory depression
  • CVS depression

What is flumazenil?

  • Antagonist of benzodiazepines at the GABA receptor.
  • Can cause benzodiazepine withdrawal.

Q25

List the major categories of the antiemetic agents.

  • Antihistamines
    • Diphenhydramine
    • Antimuscarinic, sedative and H1 blocking
    • Effective in motion sickness
  • Phenothiazines
    • Prochlorperazine, Chlorpromazine
    • Dopamine anatagonists
    • Can cause extrapyramidal symptoms
  • Metoclopramide
    • Dopamine antagonist
  • 5-HT inhibitors
    • Ondanestron, Gransitiron
  • Steroids
    • Unknown mechanism

Q26

Describe the mechanism of action of valproate.

  • Sodium Channel blocker
  • Enhances K+ efflux
  • Increase in GABA
    • Inhibition of GABA T
    • Decrease in GABA breakdown.

What potential drug interactions can occur with valproate?

  • Decrease metabolism of
    • Phenobarbitone
    • Phenytoin
    • Carbamazepine
    • Displaces phenytoin from plasma proteins
    • Inhibits its own metabolism at low doses.

Q27

What adverse reactions can be associated with the use of antipsychotic agents?

  • Anticholinergic
  • Extrapyramidal Side effects
    • Parkinsonism
    • Akathesia
    • Dystonia
    • Tardive dyskinesia
    • Neuroleptic Malignant Syndrome
    • Alpha adrenergic antagonism
    • Antihistamine
    • Jaundice
    • Endocrine

Q28

How does ondansetron work as an anti-emetic?

  • 5-HT3 antagonism  (gut and brain / central)

What are the routes of administration and dose of ondansetron?

  • Similar doses 4-8 mg oral – tablet/wafer, IV

Q29

What type of anaesthesia does ketamine produce?

  • Dissociative anaesthetic: analgesia, amnesia, catatonia +/- LOC
  • Blockade of glutamic acid (excitatory neurotransmitter) at NMDA receptor

What are the cardiorespiratory effects of ketamine?

  • CVS: HR, BP, CO increase central SNS excitation
  • Resp: decreased rate, airway reflexes remain intact, bronchodilator

Q30

What drugs can be used in the treatment of an acute attack of migraine?

  • simple analgesia (eg paracetamol, aspirin, codeine);
  • metoclopramide,
  • prochlorperazine;
  • chlorpromazine;
  • triptans eg sumatriptan (opoids can be used but not choice)
  • ergot alkaloids eg ergotamine ( +/- caffeine added);

How do triptans work?

  • structural analogue of 5-HT;
  • selective agonists at 5-HT1 receptors;
    • cause vasoconstriction,
    • particularly on cerebral arteries

Chlorpromazine can be used to treat acute migraine. What are the major side effects of chlorpromazine?

  • hypotension;
  • sedation;
  • anticholinergic (dry mouth, dry eyes, urinary retention, constipation);
  • extrapyramidal (eg acute dystonia);
  • pain with IM injections, risk of muscle necrosis

Pass criteria: Bold


GO BACK TO
Questions 11 to 20
              GO ON TO
Questions 31 to 40