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At least 1,315 records · Page 73Linked to original sources
PubMed1991

Dissolution of solid dosage form. II. Equations for the dissolution of nondisintegrating tablet under the sink condition.

An equation for dissolution from the whole surface of a nondisintegrating single component tablet under the sink condition was derived. Also, equations for several dissolution manners of the tablet under the sink condition were derived in the postulation of the dominant dissolution rate constant which determines the dissolution manner. The applicability or validity of these equations were examined by the dissolution measurements with nondisintegrating single component tablets. About one-tenth the amount of the amount needed to saturate the solution was used to prepare a tablet, and dissolution measurements were carried out with the tablet whose flat or side surface was masked with an adhesive tape in accordance with the conditions for derivation of equations. Among the derived equations, dissolution from the whole surface of a tablet was expressed by a form similar to the cube root law equation for particles. Hence, a single component tablet compressed by the use of a suitable amount was thought to behave like a single crystal. Also, equations derived for several dissolution manners were thought to be applicable for the dissolution of a nonspherical particle and crystal concerning the crystal's habit and its dissolution property, and the extended applicability was examined by converting the crystal into a simplified or idealized form, i.e., rectangle or plate.

Mathematics↗
PubMed1999

Paracetamol-propyphenazone interaction and formulation difficulties associated with eutectic formation in combination solid dosage forms.

Polymorphic behaviours of paracetamol and propyphenazone and interaction between these two compounds were investigated using differential scanning calorimetry (DSC), X-ray powder diffraction and Fourier transform-infrared (FT-IR)-spectroscopy. Binary mixtures containing various ratios of the compounds were prepared as physical and fused mixtures and analysed by DSC to study their thermal behaviours. Phase diagrams obtained from the melting endotherms of the binary mixtures demonstrated formation of an eutectic mixture at a paracetamol-propyphenazone combination of about 35:65 (w/w) with an eutectic temperature of 56 degrees C. The FT-IR spectroscopy revealed no chemical interaction due to eutectic formation, and a lower degree of crystallinity of the eutectic mixture than individual substances was observed by X-ray powder diffraction analysis. The DSC and X-ray powder diffraction data demonstrated a polymorphic change in propyphenazone as a result of melting of the compound. Tablets, containing both paracetamol and propyphenazone in a combination formulation and prepared using standard wet granulation technology, were found to have physical instability when packed in either polyvinylchloride// aluminium or polyvinylchloride/polyvinyldienechloride// aluminium blisters and stored for one month at 40 degrees C with either 75% relative humidity or without any humidity control. The instability of the tablets was more apparent under the high humidity condition.

Acetaminophen↗
PubMed2005

Mathematical algorithms applied to the multi-linear regression functions for the multicomponent determination of pharmaceutical dosage form containing three-component mixtures.

In the presence of closely overlapping spectra, the quantitative multiresolution of ternary mixtures of three active compounds paracetamol (PAR), caffeine (CAF) and acetylsalycilic acid (ASP) in tablets, without using pretreatment such as separation step and graphical procedure of spectra was accomplished by the multivariate spectral calibration models, tri-linear regression calibration (TLRC), multi-linear regression calibration (MLRC) and Cramer's rule solution (CRS) of three linear equation functions in the matrix form. In the first two models, TLRC and MLRC are based on the use of the linear regression functions at selected wavelength sets in the spectral region of 210-300 nm. In the case of CRS model, A1(1) (1%, 1 cm) were used to obtain three linear equation functions and this linear equation system was resolved by the Cramer's rule for the prediction of PAR, CAF and ASP in samples. In the TLRC and CRS models, the selection of the appropriate wavelength set was performed by the Kaiser's technique. The algorithms of these mathematical calibration models were briefly described. The validation of TLRC, MLRC and CRS models was carried out by analyzing various synthetic ternary mixtures and by using the standard addition technique. These three calibration approaches were applied to the analysis of the real pharmaceutical tablets containing PAR, CAF and ASP. The obtained results were statistically compared with each other by using experimental and statistical tests. In the comparison of TLRC and MLRC models to the classical approach, CRS technique, the successful assay results were observed for the quantitative multiresolution of ternary mixture of the subject active compounds.

Acetaminophen↗
PubMed2002

[Preparation and evaluation of press-coated aminophylline tablet using crystalline cellulose and polyethylene glycol in the outer shell for timed-release dosage forms].

In an attempt to achieve chronopharmacotherapy for asthma, press-coated tablets (250 mg), which contained aminophylline in the core tablet in the form of low-substituted hydroxypropylcellulose (L-HPC) and coated with crystalline cellulose (PH-102) and polyethylene glycol (PEG) at various molecular weights and mixing ratios in the amounts of PH-102 and PEG as the outer shell (press-coating material), were prepared (chronopharmaceutics). Their applicability as timed-release (delayed-release) tablets with a lag time of disintegration and a subsequent rapid drug release phase was investigated. Various types of press-coated tablets were prepared using a tableting machine, and their aminophylline dissolution profiles were evaluated by the JP paddle method. Tablets with the timed-release characteristics could be prepared, and the lag time of disintegration was prolonged as the molecular weight and the amount of PEG, for example PEG 500,000, in the outer shell were increased. The lag time of disintegration could be controlled by the above-mentioned method, however, the pH of the medium had no effect on disintegration of the tablet and dissolution behavior of theophylline. The press-coated tablet (core tablet:aminophylline 50 mg, L-HPC and PEG 6000; outer shell:PH-102:PEG = 8:2 200 mg) with the timed-release characteristics was administered orally to rabbits for an in vivo test. Theophylline was first detected in plasma more than 2 h after administration; thus, this tablet showed a timed-release characteristics in the gastrointestinal tract. The time (tmax) required to reach the maximum plasma theophylline concentration (Cmax) observed after administration of the press-coated tablet was significantly (p < 0.05) delayed compared with that observed after administration of aminophylline solution in the control experiment. However, there was no difference in Cmax and area under the plasma theophylline concentration-time curve (AUC0-->24) between the press-coated tablet and aminophylline solution. These results suggest that the press-coated aminophylline tablet (with the timed-release characteristic) offers a promising forms of theophylline chronotherapy for asthma.

Aminophylline↗
PubMed1994

[Pharmaceutical dosage form design of copoly (lactic/glycolic acid) microspheres. Mechanism of in vitro release of gentamicin].

The sustained release mechanism of gentamicin (GM) from lactic acid/glycolic acid copolymer (PLGA) microspheres was investigated. The terminal free carboxyl group of polymer was proved to be necessary for GM to be highly incorporated into microspheres by comparing interactions with GM and two types of polymers; free (ionized and non ionized) and the terminal esterified carboxyl group of polymer. The weight-average molecular weights (Mws) of component PLGAs of microspheres with an ionizable carboxyl group used here were approximately 4900 and 10000. The release pattern of GM was tested in phosphate buffered saline. The release rate of GM was dependent on the initial Mw and surface form. The GM release continued for 20 and 30 d from PLGA 4900- and PLGA10000-microspheres, respectively. The changes of total weight of microspheres tended to decrease with time, and the molecular weight distribution of PLGA gradually shifted to lower distribution, indicating a decrease in Mw. The changes and the shifts were dependent on the initial Mws of PLGAs but independent of their surface form. The half-times of wight loss of PLGA 4900- and PLGA10000-microspheres were about 10 and 20 d, respectively. From these results, the release profile of GM from PLGA microspheres was explained by the following three steps, i.e., 1) the release from the surface, 2) the relatively slow release caused by the obstruction of channels followed by the degradation of PLGA, 3) the release accompanied by the erosion of microspheres.

Biotransformation↗
PubMed2006

Adherence and persistence with single-dosage form extended-release niacin/lovastatin compared with statins alone or in combination with extended-release niacin.

BACKGROUND: Lipid-lowering therapies have been shown to reduce cardiovascular events and mortality; patient cooperation with therapy varies. A fixed-dose combination product, extended-release niacin/lovastatin (ERNL), has been shown to be beneficial in lipid management; however, little is known regarding patient behavior with ERNL therapy. OBJECTIVE: To evaluate patient adherence and persistence with ERNL, statin monotherapy (SM), extended-release niacin (ERN) monotherapy, and ERN plus a statin (ERN-S). METHODS: Prescription claims for lipid-lowering therapies were obtained from a pharmacy benefits manager between 2002 and 2003. Claims for a total of 2389 patients were analyzed for adherence and persistence, using medication possession ratios (MPRs) and proportions of days covered (PDCs). Adherence and persistence were defined, respectively, as an MPR or PDC greater than or equal to 0.80. Logistic regression was conducted to detect differences among groups. Covariates included age, gender, copay, and number of lipid-lowering therapies, a surrogate for disease severity. RESULTS: Average MPR scores were relatively high in all groups at 0.88, 0.81, 0.89, and 0.90 for ERNL, SM, ERN, and ERN-S, respectively. The adjusted odds ratio for adherence was lowest for SM (0.69), which was statistically significant compared with ERN-S (1.43), but not ERNL (1.00) or ERN (0.74). Persistence outcomes were poor in all groups. By the fourth quarter, patients receiving ERN-S (OR 1.31) had significantly greater persistence than those receiving ERN (OR 0.41) and SM (0.61), but not those receiving ERNL (OR 1.00). CONCLUSIONS: Managed care patients tended to be adherent to chronic lipid-lowering therapies, based on a mean MPR greater than 0.8. However, most patients failed to persist for at least 6 months.

Delayed-Action Preparations↗
PubMed2005

Comparison of near-infrared and laser-induced breakdown spectroscopy for determination of magnesium stearate in pharmaceutical powders and solid dosage forms.

Near-infrared (NIR) spectroscopy has become well established in both the pharmaceutical arena and other areas as a useful technique for rapid quantitative analysis of solid materials. Though laser-induced breakdown spectroscopy (LIBS) has not been widely applied in the pharmaceutical industry, the technique has been used for rapid quantitative analysis of solids in many other applications. One analysis amenable to each technique is the determination of magnesium stearate in solids during the lubrication blending unit operation of pharmaceutical processing. A comparative study of the utility of these two techniques for this application will be presented. Necessary sample preparations and the extent and type of matrix effects will be discussed. Additionally, it will be shown that NIR provides better accuracy and precision than LIBS with the experimental parameters used; however, LIBS showed superior selectivity as it was demonstrated to be more robust to sample matrix perturbations. Examples of blending applications will also be presented.

Drug Compounding↗
PubMed2006

Promoting absorption of drugs in humans using medium-chain fatty acid-based solid dosage forms: GIPET.

One of the most important and challenging goals in drug delivery is overcoming the poor oral absorption of high-value therapeutics that include peptides. Gastrointestinal Permeation Enhancement Technology (GIPET) attempts to address this question by safely delivering drugs across the small intestine in therapeutically relevant concentrations. GIPET is based primarily on promoting drug absorption through the use of medium-chain fatty acids, medium-chain fatty acid derivatives and microemulsion systems based on medium-chain fatty acid glycerides formulated in enteric-coated tablets or capsules. Importantly, these excipients are generally regarded as safe and the systems are formulated in such a way that there is no change in chemical composition of the active ingredient. More than 300 volunteers have been administered GIPET formulations in 16 Phase I studies of 6 separate drugs comprising both single- and repeat-dosing regimes. Oral bioavailability of alendronate, desmopressin and low-molecular-weight heparin in humans was increased using GIPET formulations compared with unformulated controls. GIPET was well tolerated by human subjects. Using fluxes of markers of epithelial permeability, the effects of GIPET on the human intestine were shown to be rapid, short-lived and reversible in vivo. These data suggest that GIPET formulations have genuine potential as a platform technology for safe and effective oral drug delivery of a wide range of poorly permeable drugs.

Administration, Oral↗
PubMed2006

Kinetic spectrophotometric analysis of pantoprazole in commercial dosage forms.

A kinetic spectrophotometric method has been developed which is based on the oxidation of pantoprazole with Fe(III) in sulfuric acid medium. Fe(III) subsequently reduces to Fe(II), which is coupled with potassium ferricyanide to form Prussian blue. The reaction is followed spectrophotometrically by measuring the increase in absorbance with time (1-8 min) at 725 nm. The initial rate method is adopted for constructing the calibration graph, which is linear in the concentration range of 5-90 microg ml(-1). The regression analysis yields the calibration equation, nu = 3.467 x 10(-6) + 4.356 x 10(-5)C. The limits of detection and quantitation are 1.46 and 4.43 microg ml(-1), respectively. The proposed method was optimized and validated both statistically and through recovery studies. The experimental true bias of all samples is < +/-2.0%. The method has been successfully applied to the determination of pantoprazole in pharmaceutical preparations.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2003

Efficacy and safety of Ritalin LA, a new, once daily, extended-release dosage form of methylphenidate, in children with attention deficit hyperactivity disorder.

OBJECTIVE: To evaluate the safety and efficacy of extended-release methylphenidate with a bimodal profile using SODAS technology (Ritalin LA ) compared with placebo in children aged 6-14 years with attention deficit hyperactivity disorder (ADHD). METHOD: This was a multicenter, double-blind, randomized, placebo-controlled, parallel-group study in children meeting Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria for ADHD. Following titration and a 1-week placebo washout period, patients were randomized to 2 weeks of double-blind treatment with either Ritalin LA (10-40 mg/day) or placebo. The efficacy assessments used were the Conners' ADHD/DSM-IV Scales for teachers (CADS-T) and for parents (CADS-P), and the Clinical Global Impression-Improvement Scale (CGI-I) completed by the investigator. The primary efficacy variable was the change from baseline (end of placebo washout) to the final rating (end of 2-week double-blind treatment) in the CADS-T Total subscale score. RESULTS: One-hundred-and-sixty-one children were treated and 134 responders were included in the intent-to-treat analysis. Ritalin LA achieved a mean change from baseline (+/- SD) on the CADS-T Total subscale of -10.7 (+/-15.68) compared with 2.8 (+/-10.59) for placebo (p < 0.0001); the effect size on the CADS-T Total score with Ritalin LA was 0.90. Additionally, 69.8% of patients in the Ritalin LA group were rated as much or very much improved on the CGI-I at final assessment compared with 40% of patients in the placebo group (p = 0.0009). The adverse events reported were generally mild or moderate, and were similar in both groups. CONCLUSION: The results demonstrate that Ritalin LA administered once daily for up to 2 weeks achieved outcomes statistically superior to placebo in children with ADHD.

Adolescent↗