Intravenous Induction Drugs Flashcards
What class of drug is Thiopental, and what structural feature explains its short duration?
Barbiturate; sulfur atom at the R2 position of the barbiturate ring.
How does Thiopental’s metabolism differ after repeated doses?
Follows zero-order kinetics (constant metabolism rate, leading to accumulation and delayed recovery).
List 3 properties of an ‘ideal IV induction drug’ that Thiopental lacks.
- Safe in porphyria (Thiopental precipitates attacks). 2. No histamine release (Thiopental causes bronchospasm). 3. Minimal CV depression (Thiopental reduces cardiac output/BP).
Propofol’s formulation includes ______. Why is it contraindicated in children for sedation?
Soya oil, egg phosphatide, glycerol; risk of ‘propofol infusion syndrome’ (metabolic acidosis, arrhythmias,lipidaemia).
Compare R(-)-ketamine and S(+)-ketamine in potency and side effects.
S(+)-ketamine: 3x more potent, shorter recovery, fewer psychomimetic effects than R(-)-ketamine.
Which drug’s metabolism is least affected by hepatic impairment?
Propofol (hepatic glucuronidation, but moderate impairment does not alter kinetics).
Etomidate inhibits ______, causing ______. Why is its use declining?
11-β-hydroxylase → adrenal cortisol suppression. Declining due to adrenal suppression morbidity.
Midazolam’s pH-dependent structure allows ______. Compare its induction dose to Propofol.
Unionized at physiological pH → rapid CNS penetration. Midazolam: 0.3mg/kg vs. Propofol: 2-2.5mg/kg.
Why is Diazepam used in resource-poor settings despite its long half-life?
Stable without infusion devices (6-hourly IM dosing); widely available.
Which drug is safest in porphyria? Least safe?
Propofol (safe); Thiopental (unsafe).
Thiopental’s reconstituted solution has a pH of ___. Why?
10.8 (alkaline solution for stability; contains 6% sodium carbonate).
Describe Thiopental’s hygroscopic property and storage requirements.
Attracts moisture; stored in airtight containers with nitrogen gas to prevent degradation.
What % of Thiopental is protein-bound? How does reduced cardiac output alter dosing?
65-85%. Reduced cardiac output → higher cerebral delivery → dose reduction required.
Which drug causes ‘dissociative anesthesia’? List 3 clinical features.
Ketamine. Features: Catalepsy, preserved reflexes, hallucinations, bronchodilation.
Match the drug to its class: Etomidate, Propofol, Midazolam.
Etomidate: Imidazole. Propofol: Phenol. Midazolam: Benzodiazepine.
Which drug causes the most significant hypotension? How to mitigate this?
Propofol (due to vasodilation). Mitigate by slow injection, especially in elderly/hypovolemic patients.
What adverse effect is unique to Etomidate infusions?
Adrenal suppression (inhibits cortisol synthesis → increased mortality in ICU sedation).
Propofol reduces ICP by ______.
Reducing cerebral blood flow/metabolic rate.
Why is Ketamine preferred in hypovolemic shock?
Maintains BP via sympathetic stimulation (tachycardia, hypertension); other agents cause hypotension.
What is Thiopental’s ‘acute tolerance’ phenomenon?
Higher plasma levels required for wakefulness after large doses vs. smaller titrated doses.
Which drug is associated with ‘green urine’? Why?
Propofol (rare side effect due to phenolic metabolites).
Compare Midazolam and Diazepam in protein binding and excretion.
Midazolam: 96% protein-bound; Diazepam: 99%. Both excreted via urine (glucuronidated metabolites).
What reversal agent is used for Benzodiazepines? Dose?
Flumazenil; 100mcg IV increments, max 2mg. Caution: Short duration → risk of re-sedation.
Thiopental’s intra-arterial injection risks ______. Management?
Arterial thrombosis/gangrene. Treat with arterial vasodilators (papaverine), heparin, stellate ganglion block.
