Enflurano

El enflurano (éter difluorometílico de 2-cloro-1,1,2-trifluoroetilo) es un éter halogenado . Desarrollado por Ross Terrell en 1963, se utilizó clínicamente por primera vez en 1966. Su uso para anestesia por inhalación aumentó durante las décadas de 1970 y 1980 ^{[ 2 ]} , pero ya no se utiliza comúnmente ^{[ 3 ] .}

El enflurano es un isómero estructural del isoflurano . Se vaporiza fácilmente, pero es líquido a temperatura ambiente.

The exact mechanism of the action of general anaesthetics has not been delineated.^[4] Enflurane acts as a positive allosteric modulator of the GABA_A,^[5][6][7][8]glycine, and 5-HT₃ receptors,^[9][10] and as a negative allosteric modulator of the AMPA, kainate, and NMDA receptors,^[10][11][12] as well as of nicotinic acetylcholine receptors.^[9]

Clinically, enflurane produces a dose-related depression of myocardialcontractility with an associated decrease in myocardial oxygen consumption. Between 2% and 5% of the inhaled dose is oxidised in the liver, producing fluoride ions and difluoromethoxy-difluoroacetic acid. This is significantly higher than the metabolism of its structural isomer isoflurane.

Enflurane also lowers the threshold for seizures, and should especially not be used on people with epilepsy.^[13] Like all potent inhalation anaesthetic agents it is a known trigger of malignant hyperthermia.

Like the other potent inhalation agents it relaxes the uterus in pregnant women, which is associated with more blood loss at delivery or other procedures on the gravid uterus.

The obsolete (as an anaesthetic) agent methoxyflurane had a nephrotoxic effect and caused acute kidney injury, usually attributed to the liberation of fluoride ions from its metabolism. Enflurane is similarly metabolised but the liberation of fluoride results in a lower plasma level and enflurane related kidney failure seemed unusual if seen at all.^[14]

El Instituto Nacional de Seguridad y Salud Ocupacional de EE. UU. (NIOSH) ha establecido un límite de exposición recomendado (REL) para la exposición a gases anestésicos residuales de 2 ppm (15,1  mg/m³ ⁾ durante un período de 60 minutos. Los síntomas de la exposición ocupacional al enflurano incluyen irritación ocular, depresión del sistema nervioso central , analgesia , anestesia , convulsiones y depresión respiratoria . ^{[ 15 ]}