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PubMed2000

A unique dosage form to evaluate the mechanical destructive force in the gastrointestinal tract.

The purpose of this study was to prepare tablets that could evaluate the destructive force in the gastrointestinal (GI) tract. Many factors are known to affect in vivo drug release from oral dosage forms. There is still relatively little information on the mechanical destructive force in the GI tract. Press-coated tablets with an extremely brittle outer layer were developed using a unique, highly hydrophobic Teflon powder that could be shaped with weak compression force. A marker drug contained in the tablets was released only when the tablets received a force larger than its predetermined crushing strength. We referred to this type of tablet as a 'destructive force dependent release system' (DDRS). A total of nine healthy, male subjects were orally administered the tablets under fed and/or fasting conditions. Tablets with a predetermined crushing strength of 1.50 N were crushed by all of the four subjects who took them under fed conditions and two of the five subjects under fasting conditions. Tablets with a crushing strength of 1.89 N were crushed by two of the six subjects who took them under fed conditions and none of the five subjects under fasting conditions. The range of mechanical destructive force in the human stomach was obtained.

Adult↗
PubMed1982

Ascorbic acid absorption in humans: a comparison among several dosage forms.

There have been few studies conducted to determine the efficiency of ascorbic acid absorption in humans. Differences in the extent of its absorption among individuals may contribute to the outcome of clinical trials. Ascorbic acid absorption in four subjects was investigated from several oral dosage forms containing 1 g of the vitamin (solution, tablet, chewable tablet, and timed-release capsule. Approximately 85% of an intravenous dose was recovered in the urine as ascorbic acid and its major metabolites. In contrast, only approximately 30% of the dose was recovered from the solution and tablet forms. A considerably smaller fraction of the dose (approximately 14%) was recovered from the timed-release capsule. There was considerable intersubject variation in ascorbic acid absorption and there appeared to be good and poor absorbers of the vitamin. Consideration should be given to the influence of the extent of ascorbic acid absorption on the results of clinical trails.

Adult↗
PubMed1999

Examination of the polymorphism of piroxicam in connection with the preparation of a new "soft-patch" type pharmaceutical dosage form.

The influence of different solvents (propylene glycol, glycerol, ethanol), as well as different technological procedures (melting, rapid and slow cooling), on the formation of polymorphous piroxicam modifications was examined in the course of the elaboration of a "soft-patch" type of semisolid pharmaceutical dosage form. The thermodynamical behavior, some physicochemical properties (such as melting point, dissolution rate), and infrared (IR) spectrum of the formed (needle and cubic) crystal modifications were studied, and the possibilities of their formation and their avoidance were examined.

Administration, Cutaneous↗
PubMed2005

Once-a-day extended-release dosage form of divalproex sodium III: development and validation of a Level A in vitro-in vivo correlation (IVIVC).

Defining a quantitative and reliable relationship between in vitro drug release and in vivo absorption is highly desired for rational development, optimization, and evaluation of controlled-release dosage forms and manufacturing process. During the development of a once-daily extended-release (ER) tablet of divalproex sodium, a predictive in vitro drug release method was designed and statistically evaluated using three formulations with varying release rates. In order to establish an internally and externally validated Level A IVIVC, a total of five different ER formulations of divalproex sodium were used to evaluate a linear IVIVC model based on the in vitro test method. For internal validation, a single-dose four-way crossover study (N = 16) was performed using fast-, medium-, and slow-releasing ER formulations and a 12-h IV infusion of valproic acid as reference. To validate the IVIVC externally, a second three-way crossover study (N = 36) was performed using slightly-fast-, medium-, and slightly-slow-releasing ER formulations. The in vivo absorption-time profile was inferred by deconvolution of the observed plasma concentration-time profiles against the unit disposition function (UDF). A linear IVIVC model was established in which the in vivo absorption was expressed as a function of in vitro drug release. Plasma profiles of ER formulations were estimated via convolution of in vitro release profiles with the UDF. Successful internal and external validations of the model were demonstrated by individual and average absolute percent prediction errors of </=9% for both C(max) and AUC(infinity). In conclusion, a Level A IVIVC describing the entire time-course of plasma concentrations was developed and validated, both internally and externally, for ER formulations of divalproex sodium.

Adolescent↗
PubMed1993

Prediction of the therapeutic dose for beta-stimulants based on preclinical data: application of oral dosage forms and aerosols to asthmatic patients.

The therapeutic doses of beta-stimulants in the treatment of bronchial asthma show wide variation among the drugs. In the present study, we tried to construct a system for prediction of the optimum clinical dose of beta-stimulants as oral dosage forms and aerosols using the data from preclinical pharmacological studies and pharmacokinetic data in humans. Values of EC50 (drug concentration that gives the half-maximum bronchodilator effect) in the in vitro studies based on isolated trachea of guinea pigs were collected from the literature. The ratios of the EC50 value of each drug to that of isoproterenol were used as the indicator of in vitro pharmacological activity. There were significant correlations between the EC50 ratios and the oral dose or the maximum plasma concentration after single oral administration, but the correlation coefficients were relatively small (r < .9). On the other hand, a linear log-log relationship was observed between the EC50 ratio and the maximum plasma unbound concentration (Cu(max)) (slope = 0.907, r = .955, p < 0.001). In the case of aerosols, a good correlation was observed between the EC50 ratio and the dose (slope = 0.770, r = .900, p < 0.01). The predicted concentration of beta-stimulants in the lung after aerosol administration tended to be higher than the Cu(max) after oral administration, suggesting the contribution of nonspecific binding in the lung tissue. These findings indicate the possibility of predicting the appropriate dose of beta-stimulants based on the preclinical pharmacological data and the pharmacokinetic data in humans.

Administration, Oral↗
PubMed1997

Application of artificial neural networks (ANN) in the development of solid dosage forms.

The application of ANN in pharmaceutical development has been assessed using theoretical as well as typical pharmaceutical technology examples. The aim was to quantitatively describe the achieved data fitting and predicting abilities of the models developed with a view to using ANN in the development of solid dosage forms. The comparison between the ANN and a traditional statistical (i.e., response surface methodology, RSM) modeling technique was carried out using the squared correlation coefficient R2. Using a highly nonlinear arbitrary function the ANN models showed better fitting (R2 = 0.931 vs. R2 = 0.424) as well as predicting (R2 = 0.810 vs. R2 = 0.547) abilities. Experimental data from a tablet compression study were fitted using two types of ANN models (i.e., multilayer perceptrons and a hybrid network composed of a self-organising feature map joined to a multilayer perception). The achieved data fitting was comparable for the three methods (MLP R2 = 0.911, SOFM-MLP R2 = 0.850, and RSM R2 = 0.897). ANN methodology represents a promising modeling technique when applied to pharmaceutical technology data sets.

Algorithms↗
PubMed2003

Once-a-day controlled-release dosage form of divalproex sodium I: formulation design and in vitro/in vivo investigations.

Divalproex sodium is a narrow therapeutic index drug that is widely used for the treatment of epilepsy, the manic episodes associated with bipolar disorder, and prophylaxis of migraine headaches. The present investigation was undertaken to design an oral dosage form that would provide once-daily administration with improved therapy and to explore the relationships between in vitro drug release and in vivo absorption. Controlled release hydrophilic matrix formulations of divalproex sodium were designed and evaluated via in vitro and in vivo studies. The release rate of divalproex sodium was modulated by varying different rate-controlling hydrophilic polymers and measured in vitro using a USP apparatus II dissolution method. Formulations with differing release rates were studied in beagle dogs and in healthy subjects. A selected formulation given once-daily was further evaluated against the commercial enteric tablet dosed twice-daily in a multiple dose study, and shown to provide desired nearly constant therapeutic plasma concentrations over the entire 24-h dosing interval. Preliminary linear relationships between in vitro dissolution and in vivo absorption were observed in both the animal model and in humans. However, the relationships were formulation dependent, indicating a need for further studies.

Animals↗
PubMed2006

Determination of terpene trilactones in Ginkgo biloba solid oral dosage forms using HPLC with evaporative light scattering detection.

A reversed phase high performance liquid chromatographic method with evaporative light scattering detection (RP-HPLC-ELSD) was developed for the quantitative determination of the terpene trilactones, ginkgolide A, B, C and J and the sesquiterpene, bilobalide in Ginkgo biloba solid oral dosage forms. Separation was achieved using a minibore Phenomenex Luna (5 microm) C18 column with dimensions 250 mm x 2.00 mm maintained at a temperature of 45 degrees C. A simple gradient method using a mobile phase of methanol:water and a flow rate of 350 microl/min facilitated baseline separation of the selected marker compounds within 14 min. The ELSD parameters affecting the detector response were optimized prior to the validation. The limits of detection and quantification were 31.25 and 62.50 ng, respectively. The percentage relative errors of the recovery ranged between -3.16 and +1.88 and both intra-day and inter-day percentage standard deviations were all better than 6%. This method was used to assay commercially available Ginkgo biloba products and proved to be suitable for the routine analysis of such products for quality control purposes.

Administration, Oral↗
PubMed2005

Quality of phenobarbital solid-dosage forms in the urban community of Nouakchott (Mauritania).

PURPOSE: Epilepsy is a major public-health problem in Africa. The quality of available drugs is a limiting factor for an adequate management. The aim of this study was to describe the proportion of poor-quality phenobarbital (PB) solid-dosage forms and evaluate the factors associated with its quality in Nouakchott (Mauritania). METHODS: A cross-sectional study was carried out within pharmacies, hospitals, and on the parallel market in March 2003. PB samples were bought by a native person and then assayed by a liquid chromatography method. A package was considered to be of good quality if the active-substance average content was between 85 and 115% of the stated content printed on the packet. RESULTS: Forty-five pharmaceutical stores were visited, enabling us to collect 146 samples of PB. Three brand names were available in Nouakchott. They originated from France, Morocco, Senegal, and Egypt. Results: A prevalence of 13.7%[95% confidence interval (CI), 8.8-20.0] of poor-quality PB was found. All samples from Morocco were underdosed. The generic active content was satisfactory, but saccharose, an excipient with a potential side effects, was identified. Two factors associated with the good quality of PB have been put forward: tablets manufactured in France and loose packaging as generics conditioned in such a way were of good quality. CONCLUSIONS: This study shows that the quality of antiepileptic drugs in Africa is still worrying. The setting up of medicine quality control in Mauritania is legitimate. Considering the good quality of generic PB and its lower cost, this type of medicine should be promoted in this region.

Anticonvulsants↗
PubMed1990

Effects of food intake and meal size on the bioavailability of sulpiride in two dosage forms.

This study examined the influences of food intake on sulpiride (100 mg) bioavailability from a commercial film-coated tablet and of the meal size (small, medium or large) on sulpiride bioavailability from an aqueous solution in three healthy male volunteers. The cumulative urinary excretions of sulpiride for 48 h (Du48) from two dosage forms following oral administration were decreased approximately 30% by food intake. Also, a good correlation was found between the bioavailability of sulpiride from the solution and size of meals with the same dietary components. These results suggest that food intake and meal size before dosing significantly affect the gastrointestinal absorption of sulpiride.

Administration, Oral↗
PubMed2001

Progesterone freeze-dried systems in sublingual dosage form.

Various polymer matrices were tested to enhance progesterone bioavailability as part of an emergency therapy. Among the different polymers used, i.e. poly(N-vinylpyrrolidone) (PVP), poly(ethylene oxide) (PEO), Dextran T70 and partially saponified poly(methyl glyoxylate) (PMGz), the latter gives the fastest solubilization rate. The best results were obtained with the lyophilized dosage form instead of a simple mixture of the drug within the polymer matrix. A nearly instantaneous solubilization was observed with PMGz copolymers bearing 10-40% of carboxylic groups and containing up to 20% of the drug. The instantaneous solubilization of the PMGz matrix is due to the hydrophilic moieties, and the presence of hydrophobic zones in PMGz promotes good affinity with the drug and optimal dispersion into the matrix.

Administration, Sublingual↗
PubMed2005

The simultaneous determination of selected flavonol glycosides and aglycones in Ginkgo biloba oral dosage forms by high-performance liquid chromatography-electrospray ionisation-mass spectrometry.

An accurate, precise and sensitive liquid chromatography-tandem mass spectrometric (LC-MS-MS) method was developed for the determination of two flavonol glycosides, rutin and quercitrin, together with the algycone markers, quercetin, kaempferol and isorhamnetin in several Ginkgo biloba solid oral dosage forms. In addition, a novel quercetin glycoside, not yet reported in Ginkgo extracts, was identified. Liquid chromatography was performed using a minibore high-performance liquid chromatography (HPLC) column (150 mm x 2.0mm i.d.) and a one step gradient of acetonitrile-formic acid (0.3%) at a flow rate of 0.5 ml/min. Baseline separation of the five selected flavonol marker compounds was achieved within 20 min at 45 degrees C. Tandem mass spectrometry was performed using electrospray ionisation (ESI) in the negative ion mode. The marker compounds exhibited linearity over the range of 3-26 microg/ml and intra- and inter-day standard deviations were better than 7% and 16%, respectively. All Ginkgo products investigated were found to contain varying amounts of target analytes.

Calibration↗
PubMed2002

Formulation of an oral dosage form utilizing the properties of cubic liquid crystalline phases of glyceryl monooleate.

Glyceryl monooleate is a Food and Drug Administration-approved food additive which has the ability to form various liquid crystalline phases in the presence of various amounts of water. The unique properties of the cubic liquid crystalline phase that result upon the presence of excess body fluids at body temperature were utilized to formulate an oral dosage form containing furosemide as the model drug. The aim was to develop a formula, which has both bioadhesive and sustained release properties of the resultant cubic phase, so that increasing gastric residence time to improve bioavailability of the drug and at the same time obtaining a sustained action. The system was found to be affected by the limited solubility of furosemide in both the carrier system and the pH of surrounding medium. As a consequence, the addition of some solubility modifiers was investigated in order to obtain the desired properties of the expected liquid crystalline system.

Absorption↗
PubMed1977

Liquid chromatography in pharmaceutical analysis VI: determination of dantrolene sodium in a dosage form.

Operating conditions are described for the qualitative and quantitative determination of dantrolene sodium by high-pressure liquid chromatography. A 10-mum porous silica column was employed, using carbon tetrachloride-dimethylformamide (90:10) as the mobile phase. The flow rate was 2.0 ml/min (1800 psig), and the peaks were detected at 375 nm. The analysis of a dosage form can be carried out within 30 min with an accuracy of 3.1%. The results agree favorably with those obtained with a modified spectrophotofluorometric method.

Capsules↗
PubMed1983

Simultaneous in vitro and in vivo evaluation of both trimethoprim and sulfamethoxazole from certain dosage forms.

The dissolution rates of trimethoprim (T), and sulphamethoxazole (S), from different brands of tablets and suspensions were studied at pH = 1.1 and 7.2. The bioavailabilities of both drugs in humans were studied by the urine excretion method. The dissolution rates were dependent on the pH of the dissolution medium, the solubilities of the drugs at the pH involved, the dosage form and the brand studied. While the dissolution rates of T from all brands studied were consistent with their pH-dependent solubility, those of S were not. The dissolution rates of S from suspensions were found to be equal at pH = 7.2, but different at pH = 1.1. A correlation existed between the dissolution rate of T at pH = 1.1 from tablets and the excretion rate in humans. With S, however, no such correlation was observed at either pH.

Absorption↗
PubMed1989

Chromatographic methods for determining the identity, strength and purity of ranitidine hydrochloride both in the drug substance and its dosage forms--an exercise in method selection, development, definition and validation.

The selection, development, definition and validation of selective stability-indicating procedures for high-performance liquid chromatographic and thin-layer chromatographic analyses of ranitidine hydrochloride are described. The procedures used in conjunction can be applied to the quality assurance and stability assessments of both the drug substance and its dosage forms and serve to establish the identity, strength and purity of this drug used in the treatment of peptic ulcer and related conditions.

Chromatography↗
PubMed2004

Effect of glucomannan and the dosage form on ethinylestradiol oral absorption in rabbits.

To the beneficial properties of dietary fiber in human health, several disadvantages can be added as the possible modification of the bioavailability of other drugs when administered by the oral route. In this study, the influence of glucomannan in the oral bioavailability of ethinyl estradiol (EE), when administered to female rabbits in two different dosage forms (enteric capsules and dispersed in water), was established. To carry out the study, three groups of six animals each were used. All animals received 1 mg kg(-1) oral EE, and rabbits in groups 2 and 3 received 1.5 g glucomannan dispersed in water or in enteric capsules, respectively, immediately before EE. When comparing the results obtained after the administration of EE/glucomannan dispersed in water with those obtained after the administration of this estrogen without fiber, we can see that Cmax is 1.4 times lower, AUC 1.9 times lower and that tmax is identical (10 min). However, after the administration of fiber in enteric capsules, AUC and Cmax are higher (4.1 and 7.8 times, respectively) than when the estrogen was administered alone, and also, there is a delay in tmax (20 min). After the administration of glucomannan in the enteric capsule, the fiber forms, as in the stomach, a highly viscous solution in the gut that would limit EE access to the mucosal surface delaying its absorption. However, this effect could be compensated by a reduction of EE metabolism in the intestinal wall, leading to a higher absorption of the estrogen.

Absorption↗