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At least 631 records · Page 35Linked to original sources
PubMed1983

Bioavailability of phenytoin on single and multiple oral doses of two dosage forms in normal subjects.

The extent and rate of absorption of phenytoin (PHT) from tablet and powder were studied in four healthy adult volunteers. It was demonstrated by urinary and fecal excretion that the almost all quantity of PHT in tablet was absorbed through the gastrointestinal tract, and the observed values of the estimated free concentration (Cest.f) estimated from mixed saliva concentration of PHT in the multiple dose were in fair agreement with the calculated values of that by using computer simulation in case of tablet. On the contrary, the variations were observed in Cest.f using therapeutic dose of PHT powder. The values of Cest.f at steady-state in tablet administration were higher than those in powder administration. The absorption ratio of PHT powder was low and variable, and decreased upon increase of dose. The ratio calculated from the Cest.f values of both dosage forms at steady-state were in good correspondence to the observed values of PHT excreted in feces.

Adult↗
PubMed1995

A supercritical fluid chromatographic method using packed columns for phenylbutazone and oxyphenbutazone in serum, and for phenylbutazone in a dosage form.

The separation of phenylbutazone (PB) and its major metabolite oxyphenbutazone (OPB) using supercritical fluid chromatography (SFC) has been investigated. The separations were studied on octadecylsilane, silica and cyano packed columns with 5% methanol in carbon dioxide as mobile phase and detection at 240 nm. The octadecylsilane column showed the most favourable chromatographic parameters for the analysis of the analytes. Recoveries of PB and OPB from spiked human serum were in the 82-83% range using solid phase extraction on an ODS cartridge. Limits of detection of the SFC assay were 0.1 microgram ml-1 for PB and 1.0 microgram ml-1 for OPB. Accuracy and precision of the method were in the 0.24-4.94% range for PB and OPB. The SFC method was directly comparable to an HPLC assay of the same analytes. The SFC method was also applied to a commercial 100 mg dosage form of PB with good recovery of PB.

Capsules↗
PubMed1985

In vitro-in vivo correlation and dissolution studies with oral theophylline dosage forms.

The dissolution rates of theophylline from six commercially available products (three uncoated and three sustained-release formulations) were determined in distilled water using the USP and rotating-filter dissolution apparatus. The effect of pH on the dissolution of these products was also examined by both methods. In addition, the effect of stirring rate on the dissolution of theophylline from these products was studied using the rotating-filter apparatus. The data obtained under all conditions were reproducible and well-described by a first-order equation. There was no significant difference between the percent of labeled content dissolved in 30 min (D30) and in 60 min (D60) obtained by the USP method and those obtained by the rotating-filter apparatus. The product-to-product variation in D30 and D60 was significant (p less than 0.001) for both the sustained-release and uncoated dosage forms. The pH of the dissolution fluid had a significant effect on the dissolution of theophylline from the products. The data obtained from the dissolution and absolute bioavailability studies in the rabbit were subjected to linear least-squares regression analysis, and good correlations were obtained between the dose-normalized peak serum level, time-to-peak, percent of the dose absorbed at 1 h and at 6 h, or the dose-normalized area under the curve from t = 0 to t = 00 and from t = 0 to t = 6 h and D30, D60, or the rate constant for dissolution. The linear relationship assumed for two of the products was used to predict bioavailability parameters from dissolution variables. The values predicted by this method were not statistically different from the actual values of these parameters.

Administration, Oral↗
PubMed2006

Sensitive spectrophotometric methods for quantitative determination of chlorprothixene in pharmaceutical dosage form.

Simple and sensitive UV-VIS spectrophotometric methods for the determination of chlorprothixene hydrochloride have been developed. One of them is based on the oxidation of chlorprothixene (CPT) by ammonium metavanadate with the formation of colourless product. The second method involves the formation of ion-pair between the drug under investigation and inorganic complexes of titanium (IV) thiocyanate followed by its extraction with mixture of butanol-chloroform (1:9, v/v). The optimum conditions for the oxidation of CPT or ion-pair formation are established. The studies are examined by UV-VIS, IR or NMR spectroscopy. The methods permit the determination of CPT over the concentration range of 2.5-25 mug/ml and 4-35 mug/ml using ammonium metavanadate or the titanium (IV) thiocyanate complex, respectively. The methods are rapid, highly reproducible and accurate with +/- 0.8%. The methods are applicable to the assay of the drug under investigation in different dosage forms and the results are in good agreement with those obtained by the official methods. Common excipients used as additives to active ingredient in pharmaceutical preparations do not interfere in the proposed methods. The extractive spectrophotometric method can be applied to the determination of chlorprothixene hydrochloride in tablets after solid phase extraction (SPE).

Antipsychotic Agents↗
PubMed2003

New colorimetric methods for the determination of trazodone HCl, famotidine, and diltiazem HCl in their pharmaceutical dosage forms.

Two sensitive and simple spectrophotometric methods are developed for the determination of trazodone HCl, famotidine, and diltiazem HCl in pure and pharmaceutical preparations. The methods are based on the oxidation of the cited drugs with iron(III) in acidic medium. The liberated iron(II) reacts with 1,10-phenanthroline (method A) and the ferroin complex is colorimetrically measured at 510 nm against reagent blank. Method B is based on the reaction of the liberated Fe(II) with 2,2-bipyridyl to form a stable colored complex with lambda(max )at 520 nm. Optimization of the experimental conditions was described. Beer's law was obeyed in the concentration range of 1-5, 2-12, and 12-32 microg mL(-1) for trazodone, famotidine, and diltiazem with method A, and 1-10 and 8-16 microg mL(-1) for trazodone and famotidine with method B. The apparent molar absorptivity for method A is 1.06x10(5), 2.9x10(4), 1.2x10(4) and for method B is 9.4x10(4 )and 1.6x10(4), respectively. The suggested procedures could be used for the determination of trazodone, famotidine, and diltiazem, both in pure and dosage forms without interference from common excipients.

Colorimetry↗
PubMedDate not supplied

High-performance liquid chromatographic determination of alpha-amino acids in pharmaceutical dosage forms using aqueous mobile phase containing copper (II) ions.

A simple high-performance liquid chromatographic method was developed and validated for the determination of three alpha-amino acids (glycine, lysine, cysteine) and the amino acid derivative (N-acetylhomocysteine thiolactone) using aqueous mobile phase containing copper (II) ions. These amino acids were extracted from tablets, vials, effervescent salts and syrups and quantitatively diluted by the mobile phase. The separation was carried out on zorbax TMS column. The mobile phase was either 1.0 x 10(-3) M CuSO4 or 1.0 x 10(-3) M CuSO4 with 1.0% trimethylamine, pH 4.0. A linear relationship was obtained between detector response at 232 nm and the concentration of the studied amino acids in the range of 1.5-50 ng/microL. The intraday precision for 10-replicate samples varied from 0.59-2.66 while the interday precision ranged from 0.91-3.55 as CV%. A good recovery percentage was obtained in the analysis of many dosage forms ranging from 96.93 to 100.85 with a CV% from 0.33 to 1.74. The presented chromatographic separation method does not depend on any pretreatment or derivatization. The described chromatographic conditions, for both linearity and sensitivity, are sufficient for the selective determination of the cited amino acids. The interference from other combined pharmaceutical ingredients was resolved.

Amino Acids↗
PubMed2004

Pharmacokinetic evaluation of an azithromycin controlled release dosage form in healthy human volunteers: a single dose study.

Azithromycin (AZI) follows a two-compartment model pharmacokinetically. The purpose of this study was to evaluate the in vivo performance of a controlled release (CR) formulation of AZI, which would eliminate the risk of high peak plasma concentrations obtained within 2-3 h after peroral administration of immediate release (IR) products. The study was conducted in twelve healthy male human volunteers to compare an experimental NIPER product (CR tablets) with Vicon (IR tablets) at the same dose level as a single-dose, randomized, one-period, two-treatment, and parallel-study. Concentrations of AZI in serum samples were assessed using the validated HPLC method. From the serum concentration-time profiles various pharmacokinetic parameters (AUC(0-96), AUC(0-inf), C(max) and T(max)) were calculated for both products. Results showed that the high peak concentration obtained by administration of a conventional IR formulation were eliminated with the CR product. A mean dosage form index (DI) of 1.17 with fluctuations of 7.57% was obtained with the CR product at steady state level, indicating reduced fluctuations at the steady state serum concentrations. Elimination of the pronounced peak as well as fluctuations reduced or minimized AZI adverse effects associated with the IR product.

Administration, Oral↗
PubMed1993

Biopharmaceutical evaluation of transnasal, sublingual, and buccal disk dosage forms of butorphanol.

A series of three-way crossover randomized studies were conducted to evaluate the absolute bioavailability of butorphanol, a potent agonist-antagonist analgesic, from transnasal, sublingual, and buccal disk formulations in order to identify a practical alternative to oral administration. In each study, healthy male volunteers received 2 mg doses of butorphanol tartrate intravenously and either transnasally, sublingually or buccally. Serial blood samples were collected over 12 h and butorphanol plasma concentrations were determined by radioimmunoassay. The plasma concentration data were subjected to non-compartmental pharmacokinetic analysis. The elimination half-life of butorphanol was about 3-5 h and was independent of the route of administration. Absorption of butorphanol following transnasal administration was faster than that observed following sublingual or buccal administration. Mean absolute bioavailabilities of sublingual tablet and buccal disk formulation were only 19 per cent and 29 per cent, respectively, but for transnasal administration the value rose significantly, to 70 per cent. Based on the results of these studies, transnasal dosage form of butorphanol was selected for further clinical trials of treatment of moderate to severe pain.

Administration, Buccal↗
PubMed1999

The application of an artificial neural network and pharmacokinetic simulations in the design of controlled-release dosage forms.

The objective of this work is to use an artificial neural network (ANN) and pharmacokinetic simulations in the design of controlled-release formulations with predictable in vitro and in vivo behavior. Seven formulation variables and three other tablet variables (moisture, particle size and hardness) for 22 tablet formulations of a model sympathomimetic drug were used as the ANN model input, and in vitro dissolution-time profiles at ten different sampling times were used as output. An ANN model was constructed by selecting the optimal number of iterations and model structure (the number of hidden layers and number of hidden layer nodes). The optimized ANN model was used for prediction of formulations based on two desired target in vitro dissolution-time profiles and two desired bioavailability profiles. For three of the four predicted formulations there was very good agreement between the ANN predicted and the observed in vitro and simulated in vivo properties. This work illustrates the potential for an artificial neural network, along with pharmacokinetic simulations, to assist in the development of complex dosage forms.

Biological Availability↗
PubMedDate not supplied

Application of pi-acceptors to the spectrophotometric determination of lisinopril in commercial dosage forms.

Two simple, rapid and sensitive spectrophotometric methods have been proposed for the determination of lisinopril in pure form and pharmaceutical formulations. The methods are based on the charge transfer complexation reaction of the drug with 7,7,8,8,tetracyanoquinodimethane (TCNQ) and p-chloranilic acid (pCA) in polar media. The lisinopril-TCNQ and lisinopril-pCA charge transfer complexes dissociate in acetone and methanol, respectively, and yield coloured TCNQ and pCA radical anions which are measured spectrophotometrically at 743 and 525 nm. Under optimised experimental conditions, Beer's law is obeyed in the concentration range of 2-26 and 25-300 microg ml-1 with molar absorptivity of 1.432x10(4) and 1.192x10(4) l mol-1 cm-1 for TCNQ and pCA methods, respectively. Both the methods have been applied to the determination of lisinopril in pharmaceutical dosage forms. Results of analysis are validated statistically.

Acetone↗
PubMedDate not supplied

Liquid chromatographic determination of levodopa and levodopa-carbidopa in solid dosage forms: collaborative study.

A liquid chromatographic method for the determination of levodopa in tablets and capsules and levodopa-carbidopa in tablets was collaboratively studied by 6 laboratories. Collaborators were supplied with duplicate powdered composites of levodopa (1 synthetic formulation, 1 commercial tablet, and 1 commercial capsule) and levodopa-carbidopa (1 synthetic formulation and 2 commercial tablets), along with individual levodopa-carbidopa tablets for content uniformity determinations. The repeatability coefficient of variation (CVo) and reproducibility coefficient of variation (CVx) for levodopa single component were 0.48 and 0.87%; for levodopa in combination, 0.50 and 0.90%; and for carbidopa, 0.77 and 1.20%, respectively. Overall, the recovery values for levodopa and carbidopa from synthetic formulations simulating tablets were 100.4 and 99.5%, respectively. The pooled CVDo and CVDx values for the individual tablet assays were 2.07 and 2.30% for levodopa, and 1.80 and 2.24% for carbidopa, respectively. The method has been adopted official first action for determination of the active ingredients in levodopa tablets and capsules and in levodopa-carbidopa tablets and for content uniformity testing in the combination dosage form.

Capsules↗
PubMed1991

The preparation and evaluation of a tablet dosage form of cyclosporine in dogs.

Cyclosporine (CsA) is commercially available for oral administration as a solution in olive oil with alcohol and an emulsifier. To improve its variable absorption and low patient acceptability, several oral formulations were prepared and tested in vitro and in vivo in dogs. A tablet formulation prepared by direct compression was then selected for comparison with the commercial oil solution placed into soft gelatin capsules. The study involved a randomized crossover design in six dogs. In order to determine absolute bioavailability and to compensate for any time-dependent changes in clearance, an intravenous tracer dose of 3H-CsA was administered along with each oral test product on each of two occasions. Absolute bioavailability (mean +/- SD) was 46.0 +/- 11.1 and 45.4 +/- 9.9% for the capsules and tablets, respectively. Cmax, tmax, and mean absorption time were not significantly different between the two products. No differences were observed in the pharmacokinetics of the intravenously administered CsA in the two experiments, which were separated by 8-13 days. We conclude that the proposed tablet formulation for CsA is equivalent in dogs to the commercial dosage form placed into soft gelatin capsules.

Administration, Oral↗
PubMed2005

In situ gelling, bioadhesive nasal inserts for extended drug delivery: in vitro characterization of a new nasal dosage form.

The purpose of this study was the preparation and characterization of sponge-like, in situ gelling inserts based on bioadhesive polymers. Hydrophilic polymers (carrageenan, Carbopol, chitosan, hydroxypropyl methylcellulose (HPMC) K15M and E5, sodium alginate, sodium carboxy methylcellulose (NaCMC), polyvinyl pyrrolidone (PVP) 90, xanthan gum) were dissolved with/without the model drug oxymetazoline HCl in demineralized water and lyophilized into small inserts. The drug release, water uptake, mechanical properties, X-ray diffraction and bioadhesion potential of the nasal inserts were investigated. A sponge-like structure of nasal inserts was formed with amorphous, but not with crystalline polymers during the freeze-drying process. The insert hardness increased with the glass transition temperature of the polymer (PVP25<PVP30<PVP90). The bioadhesion potential was governed by the polymer ability to interact with mucin/agar (highest for carrageenan, Carbopol, xanthan gum and NaCMC). Inserts prepared from low molecular weight polymers resulted in polymer dissolution and fast drug release (HPMC E5, Na-alginate, PVP90). The drug release from inserts prepared from high molecular weight polymers (carrageenan, Carbopol, chitosan, HPMC K15M, NaCMC, xanthan gum) was a complex interplay of osmotic forces, water uptake and electrostatic interactions between drug and polymer. The drug release decreased with higher polymer content and increased drug loading of the insert. Bioadhesive nasal inserts have a high potential as new nasal dosage form for extended drug delivery.

Adhesiveness↗
PubMed1990

Formulation and dosage form design in drug-induced topical irritation of the gastrointestinal tract.

To test drugs for topical effects on gastrointestinal mucosa, a new in situ rabbit colon model was used that permits direct application of drugs in suspensions from gel cups, solutions, or commercially available tablets and capsules onto rabbit colonic mucosa for up to 8 hr. For each agent tested an irritation index was calculated--the product of the area of the mucosa affected by drug exposure and a numerical score for observed effect. Irritation indices ranged from 0 (no effect) to 25.6 (maximal irritation measurable). In general, the immediate release of drug onto tissue elicited the greatest effect, whereas slow or controlled release of drug produced the least response. Topical irritation was found to be a function of (1) the drug, (2) the formulation, (3) the delivery rate, and (4) the concentration. The gastrointestinal therapeutic system (GITS) of potassium chloride and of brompheniramine/pseudoephedrine produced far less irritation than current commercial formulations of these drugs. The rabbit colon model is proposed as a useful screening tool during drug development to aid in selecting the formulation of an oral dosage form that will minimize topical irritation.

Animals↗
PubMed1987

Bioavailability of three oral dosage forms of cisapride, a gastrointestinal stimulant agent.

Relative bioavailability of the investigational gastrointestinal stimulant agent cisapride after oral administration was determined in healthy men. Treatments administered were (A) two 5-mg tablets; (B) one 10-mg tablet; (C) 10 mL of a 1-mg/mL suspension; and (D) 10 mL of a 1-mg/mL aqueous reference solution. The study had a randomized four-way, crossover design; drug administration was followed by a standard breakfast. Plasma cisapride concentrations in blood samples drawn over 48 hours were measured by high-performance liquid chromatography. Individual and mean values for bioavailability parameters were subjected to analysis of variance followed by multiple comparison testing. Time to maximum concentration was shortest after administration of the solution. There was a significant difference in mean peak plasma concentrations between treatment A (48.8 +/- 12.8 ng/mL) and treatment D (41.6 +/- 10.6 ng/mL), with treatment A producing a 17.3% higher peak concentration. No significant differences between treatments were found for area under the plasma concentration-time curve. The overall mean elimination half-life was 7.01 hours. The results of the study indicate that the tablet and suspension dosage forms of cisapride are bioequivalent to the reference solution.

Administration, Oral↗
PubMed1998

Determination of tramadol in various dosage forms by capillary isotachophoresis.

Cationic capillary isotachophoresis (ITP) with conductometric detection has been used for separating and determining milligram amounts of tramadol [2-dimethylaminomethyl-1-(3-methoxyphenyl)-cyclohexanol hydrochloride] (I) in seven commercial mass-produced pharmaceutical preparations. The optimised ITP electrolyte system consisted of 5 mM potassium picolinate + 5 mM picolinic acid (pH 5.25) as the leading electrolyte and 10 mM formic acid as the terminating electrolyte. The driving and detection currents were 50 microA (for 320 s) and 10 microA, respectively (a single analysis took 12-15 min). Under such conditions the effective mobility of I was determined as 24.26 x 10(-9) m2 V(-1) s(-1) (with tetraethylammonium ion as standard); thermodynamic pKa value of I was 9.44 +/- 0.03 (n = 8) as determined by UV spectrophotometry at 25 degrees C and I = 0.01 (NaCl). The calibration graph relating the ITP zone length to the concentration of I was rectilinear (r = 0.99997) in the range 15-180 mg l(-1) of I. The relative standard deviation (RSD) was 0.21% (n = 6) when determining 60 mg l(-1) of I in pure test solution. Sample pre-treatment of the dosage forms involved dilution or extraction of I with water (for suppositories the extraction was carried out in an ultrasonic bath at 40 degrees C for 10 min). The method was suitable for determining 50 or 100 mg ml(-1) of I in injections and drops, 50 mg of I in capsules, and 100 mg of I in suppositories with RSD values 0.4 to 1% (n = 6). According to the validation procedure based on the standard addition technique the recoveries were 97.2-100.1% of I.

Analgesics, Opioid↗
PubMedDate not supplied

Voltammetric determination of benazepril and ramipril in dosage forms and biological fluids through nitrosation.

A simple and highly sensitive voltammetric method was developed for the determination of benazepril (I) and ramipril (II). The compounds were treated with nitrous acid, and the cathodic current produced by the resulting nitroso derivatives was measured. The voltammetric behavior was studied by adopting direct current (DCt), differential pulse (DPP), and alternating current (ACt) polarography. Both compounds produced well-defined, diffusion-controlled cathodic waves over the whole pH range in Britton-Robinson buffers (BRb). At pH 3 and 5, the values of diffusion-current constants (Id), were 5.90 +/- 0.40 and 6.66 +/- 0.61 for I and II, respectively. The current concentration plots for I were rectilinear over the range of 1.5-40 and 0.1-30 microg/mL in the DCt and DPP modes, respectively; for II, the range was 2-30 and 0.1-20 microg/mL in the DCt and DPP modes, respectively. The minimum detectabilities (S/N = 2) were 0.015 microg/mL (about 3.25 x 10(-8)M) and 0.012 microg/mL (about 2.88 x 10(-8)M) for I and II, respectively, adopting the DPP mode. Results obtained for the proposed method when applied to the determination of both compounds in dosage forms were in good agreement with those obtained using reference methods. Hydrochlorthiazide, which is frequently co-formulated with these drugs, did not interfere with the assay. The method was also applied to the determination of benazepril in spiked human urine and plasma. The percentage recoveries adopting the DPP mode were 96.2 +/- 1.21 and 95.7 +/- 1.61, respectively.

Angiotensin-Converting Enzyme Inhibitors↗