Forane

DRUG DESCRIPTION

FORANE (isoflurane, USP), a nonflammable liquid administered by vaporizing, is a general inhalation anesthetic drug. It is 1-chloro-2, 2,2-trifluoroethyl difluoromethyl ether, and its structural formula is:

FORANE (isoflurane) Structural Formula Illustration

Some physical constants are:

Molecular weight..............................184.5
Boiling point at 760 mm Hg...................48.5C (uncorr.)
Refractive index n20D..........................1.2990-1.3005
Specific gravity 25/25C....................1.496
Vapor pressure in mm Hg**

20C........238
25C...........295
30C...........367
35C...........450

**Equation for vapor pressure calculation:
log10Pvap = A + B/T where A = 8.056 T
B = -1664.58
T = C + 273.16 (Kelvin)

Partition coefficients at 37C:

Water/gas.................0.61
Blood/gas.................1.43
Oil/gas.......................90.8

Partition coefficients at 25C - rubber and plastic

Conductive rubber/gas.................62.0
Butyl rubber/gas.................75.0
Polyvinyl chloride/gas.................110.0
Polyethylene/gas.................~2.0
Polyurethane/gas................. ~1.4
Polyolefin/gas .................~1.1
Butyl acetate/gas................. ~2.5
Purity by gas chromatography ................. > 99.9%
Lower limit of flammability in oxygen or nitrous oxide at 9 joules/sec. and 23C.................None
Lower limit of flammability in oxygen or nitrous oxide at 900 joules/sec. and 23C.................Greater than useful concentration in anesthesia.

Isoflurane is a clear, colorless, stable liquid containing no additives or chemical stabilizers. Isoflurane has a mildly pungent, musty, ethereal odor. Samples stored in indirect sunlight in clear, colorless glass for five years, as well as samples directly exposed for 30 hours to a 2 amp, 115 volt, 60 cycle long wave U.V. light were unchanged in composition as determined by gas chromatography. Isoflurane in one normal sodium methoxide-methanol solution, a strong base, for over six months consumed essentially no alkali, indicative of strong base stability. Isoflurane does not decompose in the presence of soda lime (at normal operating temperatures), and does not attack aluminum, tin, brass, iron or copper.



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