Piero Corti

Evaluation of transcutol as a clonazepam transdermal permeation enhancer from hydrophilic gel formulations.

The influence of diethyleneglycol monoethyl ether (transcutol), alone or in combination with propylene glycol, on clonazepam permeation through an artificial membrane and excised rabbit ear skin from Carbopol hydrogels was investigated. Drug kinetic permeation parameters were determined for both series of experiments and compared. Rheological characteristics, drug solubility and membrane/vehicle partition coefficient for each gel formulation were also determined, and their role in the formulation performance was investigated. Both series of experiments showed an increase of drug permeation as a function of transcutol content in the formulation. The combination of transcutol and propylene glycol resulted in a synergistic enhancement of clonazepam flux. A different trend was found in experiments with gels containing mixtures of the two enhancers, where an increase (in the case of artificial membrane) or a decrease (in the case of rabbit ear skin) of drug permeation was found by increasing the transcutol/propylene glycol ratio in the mixture. Such a result is explained on the basis of the particular mechanism of action demonstrated for transcutol which associates the increase of drug solubility to the potent effect of a depot in the skin.

Application of near-infrared reflectance spectrometry to the analytical control of pharmaceuticals: ranitidine hydrochloride tablet production

The possibility of applying near-infrared reflectance spectrometry to the control of the production cycle of ranitidine hydrochloride tablets was investigated. The results were good for the identification of ranitidine hydrochloride drug substance, mixtures for tablets, cores and coated tablets. The determination of the compound and of its water content also gave satisfactory results.

Near infrared transmittance analysis for the assay of solid pharmaceutical dosage forms

The recent commercial availability of near infrared spectrometric instruments for the transmittance analysis of solids makes it possible to analyse solid drugs in their finished form. Application of the method to the control of the assay of the active ingredient in diphenhydramine tablets gave results comparable to those obtained in reflectance mode with whole and milled tablets.

Near-infrared reflectance spectrometry in the determination of the physical state of primary materials in pharmaceutical production

Near-infrared reflectance spectrometry was used to determine various physical characteristics of primary materials currently used in the pharmaceutical industry. It was possible to distinguish substances with different grain sizes, crystalline states and densities.

Quantitative Fourier transform near-infrared spectroscopy in the quality control of solid pharmaceutical formulations

In this study we investigated the capacities of near-infrared spectroscopy equipment with Fourier transform spectral analysis and an optical fibre probe. The equipment was tested for quantitative analysis during pharmaceutical production of powders containing benzydamine hydrochloride and tricetol (a p-toluene sulfonate analogue of cetyltrimethylammonium bromide), pills containing ibuprofen and tablets containing paracetamol.

High-performance liquid chromatographic assay of erythromycin from biological matrix using electrochemical or ultraviolet detection.

Two chromatographic methods were developed for the determination of erythromycin A (EA) residues in animal tissues (muscle, liver, kidney and fat of cattle, pigs and poultry) and cows milk. In addition to a more traditional method using electrochemical detection, we developed an original alternative method based on UV detection at 236 nm, by pretreating to create a chromophore in the molecule. An internal standard was used with both methods to check the variability of the analytical system. Analysis times and performance were compared. The recovery of EA from various matrices was greater than 95%. For both methods the quantification limit for EA was 0.25 microgram ml-1 for plasma, 0.025 microgram g-1 for milk and 0.125 microgram g-1 for the other biological matrices. The methods can be used to check for EA residues in these matrices; in fact, the statutory maximum residue limits (MRLs) of EA are 0.4 microgram g-1 in muscle, kidney, liver and fat of beef cattle, sheep, pigs and poultry, and 0.04 microgram g-1 in cows and sheeps milk.

Application of near-infrared reflectance analysis to the integrated control of antibiotic tablet production

The possibility of applying near-infrared reflectance analysis to the integrated control of the production cycle of cefuroxime axetil tablets was investigated. The results were good for the identification of cefuroxime axetil primary material, granules, cores and tablets. The determination of the compound and of its water content also gave satisfactory results.

High Performance Thin Layer Chromatographic Quantitative Analysis of Picrocrocin and Crocetin, Active Principles of Saffron (Crocus sativusL.‐Iridaceae): A New Method

A new high performance thin layer chromatographic method has been developed for the quantitative analysis of the active principles (picrocrocin and crocetin) of saffron (Crocus sativusL.). The method is easily applied, shows good reproducibility and is rapid and sensitive. The technique overcomes the problems usually found with other analytical approaches to saffron determination which generally are not repeatable and deal with identification of adulterations more than with the analysis of constituents.

Nuclear relaxation studies in ligand-macromolecule affinity index determinations

Abstract An ‘affinity index’, representing the global affinity between a ligand and a biomacromolecular receptor, is proposed. It is determined as the slope of the linear relations between ΔR1SE and the receptor concentration and has the advantage of providing a measure of the ligand-biomacromolecule global affinity which is independent of the number of interaction sites. The method was applied to the calculation of the lamotrigine-albumin affinity index.

Determination of some quinolones in tablets, human plasma and urine by differential-pulse polarography

Abstract A differential pulse polarographic method was developed for the determination of norfloxacin, cinoxacin and pipemidic. oxolinic and piromidic acids in tablets and biological fluids. Well defined peaks, useful for an accurate and precise assay, were observed in the appropriate supporting electrolyte (Britton-Robinson and phosphate buffers), depending on both the kind of preparation (tablet, plasma or urine) and the quinolone investigated. The analysis of quinolones in biological fluids requires a prior clean-up procedure (treatment with acetonitrile and 2 M potassium hydroxide for plasma and solid-liquid extraction for urine) while common excipients were found not to interfere in the tablet assay. In each of the above situations (tablet, plasma or urine), good precision of the method evaluated as the CV, was found.