Pharmacological properties : תכונות פרמקולוגיות

Pharmacodynamic Properties

5.1   Pharmacodynamic properties
Desflurane is one of a family of halogenated methylethylethers which are administered by inhalation producing a dose-related, reversible loss of consciousness and of pain sensations, suppression of voluntary motor activity, reduction of autonomic reflexes and sedation of respiration and the cardiovascular system.
Other members of the series include enflurane and its structural isomer isoflurane which are halogenated with chlorine as well as fluorine. Desflurane is halogenated exclusively with fluorine. As suggested by its structure, the low blood/gas partition coefficient of desflurane (0.42) is lower than that of other potent inhaled anaesthetics such as isoflurane (1.4) and even lower than that of nitrous oxide (0.46). These data indicate that desflurane would meet the need for an agent characterised by rapid recovery and that it is particularly suited for use in outpatient anaesthesia where this is an important property.
Animal studies showed a more rapid induction and recovery from anaesthesia than for isoflurane, with a similar cardiorespiratory profile.
There were no signs of epileptogenic or other untoward effects on EEG, and adjuvant drugs produced no unanticipated or toxic EEG responses during anaesthesia with desflurane.
Studies in pigs bred to be susceptible to malignant hyperthermia (MH) indicated that desflurane is a potential trigger for MH.

Pharmacokinetic Properties

5.2   Pharmacokinetic properties
 a.      General Characteristics
As predicted from its physicochemical profile, pharmacokinetic studies in animals as in man indicate that desflurane washes into the body more rapidly than other volatile anaesthetic agents, suggesting a more rapid induction of anaesthesia. It also washes out of the body more rapidly, allowing quick recovery and flexibility in adjustment of the depth of anaesthesia. Desflurane is eliminated via the lungs, undergoing only minimal metabolism (0.02%).
 b.      Characteristics in patients

The pharmacological effect is proportional to the inspired concentration of desflurane.
The main adverse effects are extensions of the pharmacological action.
MAC decreases with increasing age. A reduction of dosage is recommended in hypovolaemic, hypotensive and debilitated patients, as discussed under Warnings above.