Desflurane

[SH4:p43-p46]

Quick summary

• Fluorinated methyl ethyl ether
• Differ from isoflurane by substitution of a fluorine for chlorine on alpha-ethyl of isoflurane

Chemical structure

Fluorinate (rather than chlorination) causes

• Increased vapour pressure
  * Less intermolecular attraction
  * Vapour pressure at 20 degrees is 669 mmHg (cf. 240 mmHg for iso)
• Increased stability
  * Much less metabolism
• Decreased potency
  * MAC = 6.6% (cf. 1.17% for isoflurane)

Properties

• Low solubility
  * Blood:gas = 0.42
• Requires a special heated and pressurised vapouriser which requires electricity
• Pungent smell
  * Cannot be used for gas induction

Clinical relevance

• Increased incidence of salivation, breath-holding, coughing, or laryngospasm when >6% inspired desflurane is used in an awake patient
• Produces highest level of carbon monoxide (of all AAs) when reacting with the strong base in carbon dioxide absorber

 

Usage

What is the drug used for?

Structure

Structure

What is the proper name of the drug's structure?

What does the drug's structure look like?

Structure-activity relationship

How does the drug's structure change its activity or characteristics?

Pharmacodynamics

Main actions

Mechanisms of action

What receptors does the drug act on?

Where are these receptors?

What are the effects of these actions?

Effects by systems

 

(CNS, CVS, Resp, GIT, others)

Side Effects/Toxicity

What are the side-effects of the drug?

What happens in overdose? What are the toxic side-effects?

 

 

Pharmacokinetics (PK)

Absorption

How is the drug absorbed? Route of administration?

What is the bioavailability with non-IV routes?

Distribution

Where does the drug first get distributed to (e.g. VRG, muscle, fat)?

Where do the drug accumulate mostly?

How fast does it redistribute?

Does it cross BBB or placenta?

(Includes the Vd and Protein-binding)

Metabolism

How is the drug metabolised? Where does the metabolism take place(Liver, kidney, other organs)

What are the metabolites? Are they active or toxic?

Elimination

How is the drug eliminated? How are the metabolites eliminated?

How much of the drug is eliminated unchanged?

Clearance

Action profile

T1/2 (in different phases, alpha, beta, etc)

Onset of action, duration of action, time to peak effect

Physicochemical properties

Acid or base? pKa?

Pharmaceutics

Presentation

Composition

Price

Clinical

Administration

route of administration, and the dosage for each different route.

 

Indications/contraindication/precautions

When should the drug be used?

When should the drug NOT be used?

When should the drug be used, but only with caution?

 

Interactions

What other things can the drug interact with?

 

Special consideration

What issues should be considered when the drug is used in special circumstances, e.g.:

• Pregnancy/lactation
• Elderly
• Paediatrics
• Renal disease
• Hepatic disease

 

 

Trivia

History

 

Others