PubMed · 5769693
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R C Gibbs. 1969. Drugs for some dermatologic problems.. https://doi.org/10.7547/87507315-59-5-182
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An accurate, sensitive, and selective reversed phase high performance liquid chromatographic (HPLC) method was developed for the analysis of two halogenated 8-hydroxyquinoline derivatives; clioquinol (CQN) and iodoquinol (IQN). The proposed method depends on the complexation ability of the studied compounds with Pd(II) ions. Reversed phase chromatography was conducted using a 300 x 3.9 mm i.d. stainless steel column packed with 10 microm Bondclone phenyl at ambient temperature. A solution containing 0.005% w/v of Pd(II)-chloride in a mixture of acetonitrile-methanol-water (3:3:4 v/v/v) of pH 3.7 as a mobile phase pumped at a flow rate of 0.75 ml min(-1). UV-detection was performed at 282 and 285 nm for CQN and IQN, respectively. The method showed excellent linearity in the range 0.05-1.8 and 0.1-3.0 microg ml(-1) with limit of detection (S/N=2) 4.8 ng ml(-1) (1.57 x 10(-8) M) and 6.4 ng ml(-1) (1.61 x 10(-8) M) for CQN and IQN, respectively. The suggested method was successfully applied for the analysis of the studied drugs in bulk with average% recoveries of 99.68+/-0.44 for CQN and 99.65+/-0.53 for IQN. The proposed method was successfully applied for the analysis of the studied drugs in single or combined dosage forms with average% recoveries of 99.41+/-0.51-100.02+/-0.63. The proposed method could be used successfully for the determination of the studied compounds in the presence of their degradation product as they could be eluted with different retention times. The presence of metronidazole (MNZ) or tolnaftate (TFT) with the studied drugs does not affect their accurate determination. The results obtained were favorably compared with those obtained by the reference method. The results were satisfactorily, accurate, and precise.
Evidence for multiple functional active oxidants in cytochrome P450-catalyzed reactions was previously obtained in this laboratory with mutants in which proton delivery was perturbed by replacement of the highly conserved threonine residue in the active site by alanine, thus apparently interfering with the conversion of the peroxo-iron to the hydroperoxo-iron and the latter to the oxenoid-iron species. These enzymes have now been employed to examine the reaction in which cytochrome P450 in liver microsomes is known to effect ipso-substitution, the elimination of p-substituents in phenols to yield hydroquinone. As shown with purified NH(2)-truncated cytochromes in a reconstituted enzyme system, the reaction exhibits an absolute requirement for cytochrome P450 and NADPH-cytochrome P450 reductase. Under optimal conditions truncated cytochrome P450 2E1 is active with 10 of the p-substituted phenols examined. Of particular interest, the corresponding cytochrome with threonine-303 replaced by alanine is from 1.5- to 50-fold higher in activity with the p-chloro, -bromo, -nitro, -cyano, -hydroxymethyl, -formyl, and -acetyl derivatives, and the reaction with the p-benzoyl, -methyl, and -t-butyl compounds is catalyzed by the mutant enzyme only. The results implicate the hydroperoxo-iron species as an electrophilic active oxidant in cytochrome P450-catalyzed aromatic ipso-substitution.
BACKGROUND AND OBJECTIVE: Pulsed KTP lasers effectively treat facial telangiectasia without purpura production. Transient side effects following treatment include erythema, edema, and vesiculation leading to crust formation. The aim of this study was to investigate the utility of an aqueous gel in reducing side effects associated with pulsed KTP laser treatment of facial telangiectasia. STUDY DESIGN/MATERIALS AND METHODS: Nineteen patients with extensive facial telangiectasias were treated with a pulsed KTP laser (Versapulse, Coherent, Palo Alto, CA). The laser was used with the water cooled handpiece chilled to 4C, a 4 mm spot size, a 10-millisecond pulse duration and a fluence of 9.5 J/cm2. One side of the face was treated with the laser using the cooling handpiece alone. The other side was treated using the cooling handpiece applied to a 2-mm film of aqueous gel spread over the treatment area. RESULTS: Treatment side effects, including pain, erythema, edema, vesiculation, and crusting were scored following treatment with and without the aqueous gel. Use of the aqueous gel in conjunction with the cooling handpiece decreased the incidence and severity of pain, erythema, edema, and crusting following pulsed KTP laser treatment of facial telangiectasia. Most patients demonstrated 50-75% clearance of their telangiectasias 1 month after one treatment session, and use of the gel did not alter the treatment efficacy. CONCLUSIONS: The application of an aqueous gel during pulsed KTP laser treatment of facial telangiectasia improves treatment associated side effects without affecting vessel clearance.