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Forane Dosage

Medically reviewed by Last updated on April 19, 2021.

Generic name: ISOFLURANE 1mL in 1mL
Dosage form: inhalant


Premedication should be selected according to the need of the individual patient, taking into account that secretions are weakly stimulated by FORANE, and the heart rate tends to be increased. The use of anticholinergic drugs is a matter of choice.

Inspired Concentration:

The concentration of isoflurane being delivered from a vaporizer during anesthesia should be known. This may be accomplished by using:

a. Vaporizers calibrated specifically for isoflurane;

b. Vaporizers from which delivered flows can be calculated, such as vaporizers delivering a
saturated vapor which is then diluted. The delivered concentration from such a vaporizer may
be calculated using the formula:

% isoflurane = 100 PVFV / FT(PA – PV)




Pressure of atmosphere



Vapor pressure of isoflurane



Flow of gas through vaporizer



Total gas flow (mL/min)

Isoflurane contains no stabilizer. Nothing in the agent alters calibration or operation of these vaporizers.


Induction with isoflurane in oxygen or in combination with oxygen-nitrous oxide mixtures may produce coughing, breath holding, or laryngospasm. These difficulties may be avoided by the use of a hypnotic dose of an ultra-short-acting barbiturate. Inspired concentrations of 1.5 to 3.0% isoflurane usually produce surgical anesthesia in 7 to 10 minutes.


Surgical levels of anesthesia may be sustained with a 1.0 to 2.5% concentration when nitrous oxide is used concomitantly. An additional 0.5 to 1.0% may be required when isoflurane is given using oxygen alone. If added relaxation is required, supplemental doses of muscle relaxants may be used.

The level of blood pressure during maintenance is an inverse function of isoflurane concentration in the absence of other complicating problems. Excessive decreases may be due to depth of anesthesia and in such instances may be corrected by lightening anesthesia.

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