Disease relevance of Norflurane

• There has been little published human or animal research evaluating possible neurobehavioral toxicity from longer HFC 134a exposures, as may be expected to occur in operational scenarios [1].
• Effects on lung function, symptoms, and bronchial hyperreactivity of low-dose inhaled beclomethasone dipropionate given with HFA-134a or CFC propellant [2].

High impact information on Norflurane

• Two commercially available salbutamol metered dose inhalers using a novel hydrofluorocarbon HFC-134a as propellant were equally as potent and efficacious as conventional CFC-MDIs, as were the Rotahaler and Clickhaler dry powder inhalers (DPIs) [3].
• The abilities of halothane and the fluoroethane chlorofluorocarbon (CFC) substitutes, FC-123, FC-133a, FC-124, FC-134a and FC-125, to stimulate cytochrome P450 activities and 2-chloro-1,1-difluoroethene (CDE) defluorination in hepatic microsomes from phenobarbital-treated rabbits were compared [4].
• In vivo rabbit ear vasculature was used as a model of cutaneous anomalies to assess the influences of CSC (with R-134a or R-404a) on the photothermolysis of dermal blood vessels [5].
• We investigated the potential of CSC with R-404a (boiling point approximately -46.5 degrees C at 1 atm), which has a lower boiling point than R-134a, for improved therapeutic outcome in dark human skin at three levels: in vitro (epoxy resin skin phantom), ex vivo (normal dark human skin sample), and in vivo (skin of the rabbit external ear) [5].
• An atmospheric pressure chemical ionization study of the positive and negative ion chemistry of the hydrofluorocarbons 1,1-difluoroethane (HFC-152a) and 1,1,1,2-tetrafluoroethane (HFC-134a) and of perfluoro-n-hexane (FC-72) in air plasma at atmospheric pressure [6].

Biological context of Norflurane

• Two TAA aerosol formulations have been developed using a non-chlorofluorocarbon propellant, HFA-134a (Azmacort HFA Inhalation Aerosol delivering TAA 75 microg/puff or 225 microg/puff) [7].
• A study comparing the clinical pharmacokinetics, pharmacodynamics, and tolerability of triamcinolone acetonide HFA-134a metered-dose inhaler and budesonide dry-powder inhaler following inhalation administration [8].
• We report the first study of R-134a (also known as HFC-134a and CF3CFH2) refrigerant leakage from air conditioning (AC) systems of modern vehicles [9].
• RESULTS: A significant dose response was found for HFA-134a albuterol sulfate and CFC albuterol with regard to changes in FEV1, serum potassium, heart rate, and blood pressure after 16 cumulative inhalations [10].
• Release of F- from R- 134a biotransformation as shown by the near-total lack of dehalogenation during anaerobic incubations [11].

Anatomical context of Norflurane

• Oxidation of 1,1,1,2-tetrafluoroethane in rat liver microsomes is catalyzed primarily by cytochrome P-450IIE1 [12].
• Defluorination of 1,1,1,2-tetrafluoroethane (R-134a) by rat hepatocytes [13].

Associations of Norflurane with other chemical compounds

• Cumulative dose response study comparing HFA-134a albuterol sulfate and conventional CFC albuterol in patients with asthma [10].
• As part of its toxicological evaluation we assessed the in vitro metabolism of 1,1,1,2-tetrafluoroethane (R-134a), a non-ozone-depleting chemical likely to replace dichlorodifluoromethane (R-12) as an air-conditioning refrigerant [13].
• Pyridine also potently induced defluorination of R-134a catalyzed by rabbit liver microsomes [12].
• Defluorination of R-134a was inhibited by CO, lack of NADPH, or heat denaturation of microsomes [11].
• Halothane (1,1,1-trichloro-2-bromo-2-chloro-ethane), although not defluorinated by hepatocytes maintained with 95% O2, inhibited defluorination of R-134a [13].

Gene context of Norflurane

• In this study, we determined that the human ortholog of P-450 2E1 plays a role of similar importance in the metabolism of HFC-134a [14].
• Dominant role of cytochrome P-450 2E1 in human hepatic microsomal oxidation of the CFC-substitute 1,1,1,2-tetrafluoroethane [14].
• The chlorofluorocarbon substitute 1,1,1,2-tetrafluoroethane (HFC-134a) is subject to metabolism by cytochrome P-450 in hepatic microsomes from rat, rabbit, and human [14].
• Blood samples for HFA-134a in the MDI A group were collected on day 28 to measure systemic absorption [15].
• 3. In a peri- and post-natal study, rats were exposed to HFA-134a from days 17 to 20 of pregnancy and days 1 to 21 post partum to atmospheres of 1800, 9900 or 64,400 p.p.m. 4 [16].

Analytical, diagnostic and therapeutic context of Norflurane

• R-134a was measured using gas chromatography (GC) with a flame ionization detector (FID) [9].
• PURPOSE: To assess the physical stability and aerosol characteristics of suspensions of hollow porous microspheres (PulmoSpheres) in HFA-134a [17].
• We have recorded the vibrational absorption spectrum of 1,1,1,2-tetrafluoroethane (HFC-134a) in the fundamental and first five CH-stretching overtone regions with the use of Fourier transform infrared, dispersive long-path, intracavity laser photoacoustic, and cavity ringdown spectroscopies [18].
• One inhaler was actuated using the press and breathe (P&B) technique and the other was breath-actuated (AH); both inhalers used HFA-134a as propellant [19].
• A gas chromatographic procedure with headspace analysis and flame-ionization detection is described for the determination of the chlorofluorocarbon substitute 1,1,1,2-tetrafluoroethane (HFA-134a) [20].

References