Metered dose inhalers III: Metaproterenol sulphate; particle size distribution and dose uniformity.

Three American products and one Canadian product were examined for content uniformity and particle size distribution. The results showed that not all products performed equally well. Some of the products exhibited high sprays early in the canister lifetime and all products demonstrated loss of prime. The particle size distributions were determined using the Andersen cascade impactor (USP Induction Port) and the fine particle fraction was determined using the twin impinger. The results showed that three of the four products had similar particle size distribution profiles. Both the Andersen cascade impactor and the twin impinger yielded the same trends in the amount of drug substance delivered to the fine particle fraction.

CYP2C19 genotyping and associated mephenytoin hydroxylation polymorphism in a Canadian Inuit population.

The CYP2C19-associated oxidation polymorphism of mephenytoin was investigated in an Inuit population living in the high Arctic of Canada. Results were obtained for 152 subjects, of whom 90 were unrelated to first degree relatives. Phenotyping was based on the capillary gas chromatographic determination of the S/R enantiomeric ratio in overnight urine collected after a dose of 100 mg (R,S)-mephenytoin. The phenotype was confirmed by determining the S/R enantiomeric ratio after acid treatment of urine samples, and for some subjects, by determining urinary recovery of 4'-hydroxymephenytoin using capillary electrophoresis analysis. DNA was analysed for the m1 and m2 mutations of CYP2C19. Three of 152 subjects (2.0%; 95% confidence limits: 0.0-4.2%) were phenotypically classified as poor metabolizers (PMs). Genotype analysis characterized three individuals as homozygous, and 28 individuals as heterozygous for the m1 mutation, the remaining individuals being homozygous for the wild-type allele. The genotype of the three PMs was concordant with that of the phenotype. DNA fingerprinting confirmed that these three individuals were genetically unrelated. The allele frequency of the CYP2C19m1 mutation, determined in unrelated subjects, was 0.12 (95% confidence limits: 0.07-0.17). CYP2C19m2 was not detected in this population. Thus, the Canadian Inuit resemble Caucasian rather than Asian populations in both the incidence of PM phenotype and the molecular basis of the polymorphism.

Metered-dose inhalers, I: Drug content and particle size distribution of beclomethasone dipropionate.

Four commercially available beclomethasone metered dose inhalers were analyzed for both spray content uniformity and particle size. The drug contents of primed and unprimed sprays collected at the beginning of the lifetime of the canister were not significantly different from those collected throughout the experiment. Particle size analysis of the four products using the Andersen Cascade Impactor Mark II showed that the distribution profiles were not identical. An existing HPLC method was modified to quantitate single sprays for content uniformity and to measure the amount on an impactor stage for particle sizing.

Chiral identification and determination of ephedrine, pseudoephedrine, methamphetamine and methcathinone by gas chromatography and nuclear magnetic resonance.

The enantiomers of the related substances methamphetamine, ephedrine, pseudoephedrine and methcathinone were determined by both gas chromatography after derivatization and by nuclear magnetic resonance using a chiral solvating agent. For GC the substances were derivatized with (R)-(+)-alpha-methoxy-alpha-(trifluoromethyl)phenylacetic acid (MTPA) to give diasteromeric derivatives. Resolution (baseline) of at least 1.6 was obtained between all derivatives. NMR determination of the enantiomers was conducted in a chiral environment by the addition of the chiral solvating agent, (R)-(+)-1,1'-bi-2-naphthol, to NMR solutions of the substances. Racemization of methcathinone was demonstrated to be facile by exposure to alkaline solutions for varying periods of time. Enantiomeric ratios of some products derived from the oxidation of ephedrine were determined.

Chiral resolution of cationic drugs of forensic interest by capillary electrophoresis with mixtures of neutral and anionic cyclodextrins.

Chiral resolution of a number of cationic drugs of forensic interest (amphetamine, methamphetamine, cathinone, methcathinone, cathine, cocaine, propoxyphene, and various alpha-hydroxyphenethylamines) is achieved via capillary electrophoresis (CE) with added cyclodextrins (CDs), including novel mixtures of neutral and anionic CDs. In the latter studies, resolution and migration speed are readily adjusted by varying the ratio of the two added CDs, as the anionic CD acts as a counter-migrating complexing reagent. The neutral CD, heptakis(2,6-di-O-methyl)-beta-CD, was found suitable for the analysis of illicit cocaine and khat leaves (Catha edulis Forsk), which contain (-)-alpha-aminopropiophenone ((-)-cathinone), (+)-norpseudoephedrine (cathine), (-)-norephedrine, and trace levels of the phenylpentenylamines (+)-merucathinone, (+)-merucathine, and possibly (-)-pseudomerucathine. The use of mixtures of the neutral and the anionic CD (beta-CD sulfobutyl ether IV) was found suitable for the analysis of illicit amphetamine, methamphetamine, methcathinone, and propoxyphene. A model is presented for the impact of mixtures of neutral and anionic CDs on migration behavior and chiral resolution in CE.

Separation, identification and determination of lumichrome in swine feed and kidney.

During surveillance of hog carcasses from Manitoba for antibiotic residues by the Health of Animals Laboratory, Agriculture Canada, Saskatoon, an unknown substance was found which produced tetracycline-like results with the methods used. This same substance was found in an implicated swine feed premix. Using various HPLC systems and columns, UV spectroscopy, reverse-phase TLC, and mass spectrometry, the substance was isolated from the feed premix, and identified as lumichrome, a photodegradation product of riboflavin. Traces of the same substance were found in riboflavin standard. Analysis of swine kidney, previously found to contain the unknown, showed the same substance was present at a level of about 1 ppm.

Identification of N-formylnorcocaine and N-benzoylnormethylecgonine in illicit cocaine.

Gas chromatographic determination of the acidic and neutral components of illicit cocaine indicated the presence of one or more common components in different samples. Isolation and examination of the spectroscopic properties of the major impurity indicated it to be N-formylnorcocaine. The material was compared with authentic material synthesized from norcocaine. N-Benzoylnormethylecgonine was also found to be present in illicit cocaine.

Stability of methadone in four vehicles for oral administration.

The stability of methadone in vehicles commonly used for oral administration was determined. Solutions of methadone were prepared in (1) orange-flavored Tang, (2) grape-flavored Kool-Aid, (3) apple juice, (4) grape-flavored Crystal Light, and (5) grape-flavored Crystal Light plus 0.1% sodium benzoate. For each of the first four preparations listed, two solutions were formulated at each methadone hydrochloride concentration of 0.2, 0.8, and 1.5 mg/mL; one set of three concentrations of each solution was stored in a refrigerator at 5 degrees C for up to 55 days, and the other set was stored unprotected from light at 20-25 degrees C for up to 17 days. Only three Crystal Light plus sodium benzoate solutions were prepared at the same methadone concentrations and stored at 20-25 degrees C for up to 29 days. Methadone concentrations were measured by high-performance liquid chromatography. Methadone was stable (loss of potency, less than 5%) for up to 17, 11, 9, and 8 days when stored at 20-25 degrees C in Kool-Aid, Tang, apple juice, and Crystal Light, respectively, and for up to 29 days when stored at 20-25 degrees C in Crystal Light plus sodium benzoate. Methadone was stable for up to 55, 49, 47, and 34 days when stored at 5 degrees C in Kool-Aid, Tang, apple juice, and Crystal Light, respectively. All the solutions that did not contain sodium benzoate and were stored at room temperature displayed unacceptable microbial growth after approximately two weeks. No significant loss of methadone potency occurred in any of the vehicles for oral administration during the study.

The examination of illicit cocaine.

A laboratory system of examination of illicit cocaine exhibits is described. Separation and identification of many of the components in exhibits are achieved by the use of capillary column gas chromatography and a Finnigan ion trap detector. Further examination and quantitation of the components of exhibits is achieved using two high performance liquid chromatographic (HPLC) systems. Both of these systems use identical reverse phase C8 columns. System 1 employs a solvent composed of 40% acetonitrile, 10% tetrahydrofuran and 50% 0.1% v/v aqueous triethylamine. The eluant is monitored at 280 nm. This system is preferred for routine quantitative analysis of cocaine and related alkaloids in exhibits. System 2 employs a solvent composed of 30% acetonitrile and 70% 0.05M phosphate buffer (pH = 5.0). The eluant from this system is monitored at both 220 and 280 nm. This system offers advantages in sensitivity. The relative retention times of a number of relevant substances as determined with gas chromatography and the two HPLC systems are given. The utility of the methodology for the identification and comparison of exhibits is demonstrated.

Identification of an imidazolinium salt, the major product from reaction of benzathine with iodine.

The isolation and identification of an imidazolinium salt are described. Unambiguous determination of structure was accomplished by independent synthesis. The isolated product interferes in the iodometric assay of the benzathine salts of penicillin.

Isolation and identification of a fluorophore from ampicillin degradation.

A fluorescent impurity in ampicillin has been isolated and identified as 2-hydroxy-3-phenylpyrazine. The product is formed under acidic conditions similar to those employed in some fluorometric assay procedures. The mechanism of the reaction is proposed to involve cyclization by condensation of the penilloaldehyde of ampicillin. The structure was confirmed by independent synthesis.

High-performance liquid chromatographic analysis of penicillin V benzathine oral suspensions.

A rapid high-performance liquid chromatographic assay for penicillin V content of penicillin V benzathine bulk drug and oral suspensions is described. Dilution of the oral suspension with methanol containing 1,3,5-trimethoxybenzene as the internal standard allowed for direct analysis on a reversed-phase column with a mobile phase of 53% methanol in 0.05 M aqueous pH 3.5 phosphate buffer. A relative standard deviation of less than 1% was obtained on commercial formulations, and the system was linear over a range 10-40 microgram injected.