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At least 1,207 records · Page 67Linked to original sources

PubMed2006

Does the preferred orientation of crystallites in tablets affect the intrinsic dissolution?

The aim of this study was to examine the effect of preferred orientation of crystallites, i.e. texture, on the intrinsic dissolution rate of some active pharmaceutical ingredients. Although it has often been speculated that the intrinsic dissolution of pharmaceutical tablets is affected by texture, no experimental evidence of this effect has been reported. The texture of acetylsalicylic acid, tolbutamide, carbamazepine and entacapone tablets was measured using three different methods both before and after the dissolution measurements. To clarify the effect of texture, texturizing and less-texturizing batches of each material were used. The texturizing batches had big needle or plate-like particles and the less-texturizing batches were prepared by grinding the texturizing powders. The USP rotation disc method was used to measure the intrinsic dissolution rate of the samples. The results indicated that the acetylsalicylic acid, tolbutamide and entacapone tablets texturized strongly in compression and the grinding of the texturizing powders decreased the degree of texture. Also the carbamazepine tablets were slightly texturized. All of the texture measurement methods used were found to give acceptable and consistent results and therefore a special texture goniometer is not required to perform these measurements. The intrinsic dissolution rate of all the tablets compacted from the ground powder was slightly higher than the intrinsic dissolution rate of the more texturized samples. However, these differences were not significant on a large scale. After the dissolution tests the degree of texture of the samples was decreased. The intrinsic dissolution rates of the samples were presumably affected by several different parameters such as texture, solubility, pH, surface energetics and crystal strains. Although only small differences were found between the intrinsic dissolution rates of texturized and less texturized samples the effect of texture on the dissolution behavior of the pharmaceuticals should be considered when performing accurate intrinsic dissolution studies.

Aspirin↗

PubMed2005

Buprenorphine tablet versus liquid: a clinical trial comparing plasma levels, efficacy, and symptoms.

We evaluated peak plasma concentrations, trough concentrations, and the 24-hour area under the concentration curve (AUC(0-24 h)) during maintenance with sublingual (SL) liquid or tablet formulations in 57 opiate-dependent volunteers. Study participants were assigned randomly to one of three SL daily buprenorphine dose pairs and maintained for 2 weeks with the liquid formulation followed by 2 weeks with the corresponding tablet dose. Plasma samples were obtained after at least 10 days of maintenance with the liquid formulation and after at least 10 days of that with the tablet formulation. The bioequivalence of the tablet compared with the liquid doses ranged from 57% to 75% based on peak concentrations, from 102% to 108% based on trough concentrations, and from 66% to 86% based on 24-hour AUC, but there was a large intersubject and intrasubject variability in plasma concentrations, with greater variability following tablets than liquid. Measures of withdrawal symptoms or illicit opioid use were not associated with buprenorphine dose, formulation, or plasma buprenorphine levels.

Administration, Sublingual↗

PubMed2002

Different geometric shaped hydrogel theophylline tablets: statistical approach for estimating drug release.

The objective of this study was to develop a mathematical equation for the calculation of drug release from different shaped matrix tablets. By this way, release rate related to the geometric shape could be predicted with the help of the developed mathematical equation. So, drug release could be estimated before the dissolution. Hydroxypropylmethylcellulose (HPMC) E50 as polymer and theophylline as active substance were used in the matrix tablets prepared for this purpose. Matrix tablets in three different geometrical shapes, namely in triangular, cylindrical and half-spherical forms were prepared by using two different drug-polymer ratio (1:0.5, 1:1) and diluent's in three different percentages (0, 20, 40%). Using rotating paddle and basket methods reported in USP XXIII carried out the release rate studies of these tablets. The Higuchi square-root time model best described the dissolution data. Differential scanning calorimetry (DSC) analysis was performed to identify any solid-state inactivation of the drug. The practical benefit of this work is to improve mathematical equation that can be used to predict accurately the required composition and in order to achieve the desired release profiles of different geometric shaped tablets. By using this equation new pharmaceutical products can be easily improved.

Analysis of Variance↗

PubMedDate not supplied

Pharmacokinetics of the progesterone-containing vaginal tablet and its use in assisted reproduction.

Natural progesterone, which is devoid of androgenic activity, is widely used in assisted reproduction for luteal and pregnancy support. The vaginal route has become the most established way to deliver natural progesterone because it is easily administered, avoids liver first-pass metabolism, and has no systemic side-effects. The vagina has a large potential for absorption, and through the 'uterine first-pass effect' vaginal administration results in higher uterine progesterone concentrations. We have investigated the pharmacokinetics of natural progesterone in the form of a vaginal tablet. A single dose of 100 mg resulted in a mean C(max) of 31.53 +/- 9.15 nmol/l with a T(max) of 6.92 +/- 3.12 h. The terminal half-life was 16.39 +/- 5.25 h. The pharmacokinetic data are discussed in relation to dose, age, and estrogen priming. Single-dose pharmacokinetics of 100 mg of progesterone vaginal tablets and gelatin capsules were evaluated over 24 h. Results indicated a similar mean T(max) of 6.92 +/- 3.12 and 6.23 +/- 6.57 h, respectively. However, a significantly higher C(max) was achieved by the vaginal tablet (31.95 +/- 9.15 and 23.85 +/- 9.57 nmol/l, respectively, P < 0.05). Continuous use of vaginal progesterone did not influence the hormonal, liver, or lipid profiles evaluated. There was no case of endometrial hyperplasia. The vaginal tablet was found to be well-tolerated, safe, and easily administered. In conclusion, progesterone-containing vaginal tablets have good pharmacokinetic properties and should be used for progesterone supplementation in IVF.

Administration, Intravaginal↗

PubMed2002

Dissolution behaviour of hydrophilic matrix tablets containing two different polyethylene oxides (PEOs) for the controlled release of a water-soluble drug. Dimensionality study.

Hydrophilic matrix tablets containing polyethylene oxides as the retarding polymer have been successfully employed in the controlled release of drugs. To evaluate the relative influence of drug diffusion and polymer erosion mechanisms in the drug delivery process, we studied the hydration behaviour of matrix tablets containing a water-soluble drug and PEOs of two different molecular weights: Polyox WSRN 1105 (Mw = 0.9 x 10(6)) and Polyox WSRN 301 (Mw = 4 x 10(6)). The hydration rate, the extent of swelling, and the erosion rate of matrices containing the polymer, the drug and tableting excipients were evaluated in comparison to tablets made of pure polymer. The results of these studies on function of the release behaviour were then discussed. The results show that the higher molecular weight PEO swells to a greater extent and tends to form, upon hydration, a stronger gel, which is therefore less liable to erosion, if compared to the lower molecular weight PEO. This difference in the erosion behaviour can explain the different efficiencies of the two polymeric products in modulating the delivery rate of the water-soluble drug. Moreover, the presence of other soluble components (drug and excipients) in the dosage form enhances the erosion trend of the tablets with a consequent reduction of the efficiency of the polymer in drug release control.

Biocompatible Materials↗

PubMed2000

Efficacy of naratriptan tablets in the acute treatment of migraine: a dose-ranging study. Naratriptan S2WB2004 Study Group.

OBJECTIVE: This study sought to compare the efficacy of several doses of naratriptan tablets with that of sumatriptan tablets and placebo in the acute treatment of a single migraine attack. METHODS: This was a randomized, double-blind, placebo-controlled, parallel-group, dose-ranging study. Patients received either naratriptan tablets (1, 2.5, 5, 7.5, or 10 mg), sumatriptan tablets (100 mg), or placebo. RESULTS: A total of 643 patients took part in the study. Two hours after dosing, headache relief was reported by significantly more patients treated with any dose of naratriptan (52%-69%) or sumatriptan (60%) than with placebo (31%) (P < 0.05). Four hours after dosing, headache relief was reported by significantly more patients treated with any dose of naratriptan (63%-80%) or sumatriptan (80%) than with placebo (39%) and by significantly more patients treated with sumatriptan 100 mg (80%) than with naratriptan 1 mg (64%), 2.5 mg (63%), or 5 mg (65%) (P < 0.05). Twenty-four-hour overall efficacy (headache relief maintained through 24 hours postdose with no worsening, no use of rescue medication, and no recurrence) was reported by more patients treated with any dose of naratriptan (39%-58%) or sumatriptan (44%) than with placebo (22%). Headache recurrence was reported in 17% to 32% of naratriptan-treated patients, 44% of sumatriptan-treated patients, and 36% of placebo recipients. The overall incidence of adverse events was similar in patients treated with naratriptan 1 mg (20%), naratriptan 2.5 mg (21%), and placebo (23%). For naratriptan 5, 7.5, and 10 mg, the incidence of adverse events was 32%, 37%, and 35%, respectively, and for sumatriptan 100 mg it was 26%. CONCLUSIONS: Our results suggest that the 2.5-mg dose of naratriptan tablets offers the optimal efficacy-to-tolerability ratio at the dose range between 1 and 10 mg. Although naratriptan 2.5 mg was less effective than sumatriptan 100 mg at 4 hours after dosing, the 2 medications showed similar efficacy at 24 hours.

Dose-Response Relationship, Drug↗

PubMed2002

Durability of efficacy and long-term safety profile of glyburide/metformin tablets in patients with type 2 diabetes mellitus: an open-label extension study.

BACKGROUND: Intensive glycemic control substantially reduces the microvascular and macrovascular complications of type 2 diabetes mellitus, although less than half of patients with diabetes achieve the target glycosylated hemoglobin (HbA1c) value recommended by the American Diabetes Association. Because monotherapy with an oral agent does not address the multiple pathophysiologic defects of diabetes, use of combination therapy appears to be warranted. A previous 32-week, randomized, double-blind, placebo-controlled trial found that treatment with glyburide/metformin tablets was associated with greater reductions in HbA1c values compared with glyburide monotherapy, metformin monotherapy, and placebo. OBJECTIVES: This study evaluated the durability of efficacy and long-term safety profile of therapy with glyburide/metformin tablets over 52 weeks. METHODS: Patients enrolled in this open-label extension study were drawn from 3 groups: those who completed the 32-week double-blind study, those who were discontinued from the double-blind study, and those who were ineligible for the double-blind study and were enrolled directly in the open-label extension study. Patients with an HbA1c of < 9% received glyburide/metformin 1.25 mg/250 mg tablets BID, and those with an HbA1c of > or = 9% received glyburide/metformin 2.5 mg/500 mg tablets BID. Primary efficacy variables included changes from baseline in HbA1c, fasting plasma glucose (FPG), and body weight at week 52. Safety was assessed based on adverse-event data and the results of physical examinations and laboratory tests. RESULTS: A total of 828 patients were enrolled in the study: 515 who completed the 32-week double-blind study, 138 who were discontinued from the double-blind study, and 175 who were directly enrolled. At week 52, the mean HbA1c value for the entire population had decreased from a baseline value of 8.73% to 7.04% (95% CI, -1.81 to -1.58). Patients who were enrolled directly had the poorest glycemic control at baseline and experienced the greatest reduction in HbA1c (-3.35%; 95% CI, -3.61 to -3.10). A reduction in mean FPG for the total population was observed as early as week 2, from 201 to 141 mg/dL (95% CI, -63.0 to -55.7). Symptoms of hypoglycemia occurred in 19.9% (165/828) of patients, although only one third of these patients had a documented finger-stick blood glucose value of > or = 50 mg/dL. CONCLUSIONS: In this 52-week, open-label extension study, glyburide/metformin tablets were well tolerated and effective in patients with type 2 diabetes. They provided rapid and sustainable reductions in HbA1c values and FPG concentrations.

Blood Glucose↗

PubMed2003

Pharmacokinetic properties of single-dose loratadine and ambroxol alone and combined in tablet formulations in healthy men.

BACKGROUND: Due to Mexico's complicated socioeconomic environment, causing a high occurrence of >1 person sharing a single room, respiratory conditions are spread easily. Respiratory conditions are the main reason for consultation with a physician. The most frequent symptoms are throat soreness and cough; therefore, a new formulation combining loratadine and ambroxol hydrochloride was designed to treat these 2 major symptoms. The combination is expected to provide relief when coprescribed with more specific therapies, such as antibiotics. OBJECTIVE: This study determined the pharmacokinetic profile of single-dose loratadine-ambroxol hydrochloride combination therapy versus each component given separately. The analyses included descarboethoxyloratadine (DCL), the primary active metabolite of loratadine. METHODS: This was a 4-week, single-center, randomized, open-label, 3-period crossover study in adult male volunteers aged 18 to 50 years and in good general health. Subjects were randomized to receive single doses of treatment A (2 loratadine 5-mg tablets + ambroxol 30-mg tablets), B (2 ambroxol 30-mg tablets), or C (1 loratadine 10-mg tablet) in 1 of 3 sequences (ABC, BCA, or CAB) per period. A 14-day washout period separated each treatment period. Plasma concentration-time data curves for each subject and treatment were analyzed by noncompart-mental methods to obtain values for area under the curve (AUC), maximum plasma concentration (C(max)), and time to reach C(max) (T(max)). RESULTS: Thirty subjects (mean [SD] age, 22.5 [2.6] years) were enrolled. All treatments were well tolerated. Formulations A and C produced similar loratadine and DCL AUC from time 0 to 24 hours (AUC(0-24)) values, but showed slightly high C(max). values for loratadine and slightly low C(max) values for DCL, indicating failure to demonstrate bioinequivalence. Formulations A and B produced similar ambroxol C(max), T(max), and AUC(0-24) values. CONCLUSIONS: In this population of healthy mate volunteers, results showed the bioavailability of loratadine and ambroxol from the new formulation and did not show impairment of absorption when the drugs were formulated in a combination tablet.

Administration, Oral↗

PubMed2000

Percolation thresholds in ultrasound compacted tablets.

Twenty matrix systems with different KCl content (as drug model, from 10 to 90% w/w) and Eudragit RS-PM (as inert excipient) were prepared using an ultrasound-assisted press and a traditional eccentric machine. The release behavior from both types of matrices was examined; the kinetic parameters for the release (intrinsic dissolution) and the technological properties of the final tablets (total porosity) were used to estimate the percolation threshold for the drug model and the excipient in both systems. For the systems compacted by ultrasound (US) the estimated value for the excipient percolation threshold ranges from 13.4 to 20.2% v/v (lower than that found for traditional tablets), that agrees with a continuum percolation model suggesting the presence of a continuum phase inside the tablet. This depends on a thermoplastic deformation of Eudragit RS-PM under ultrasound, that destroyed the particulate system of the excipient and transform it into a continuum medium. The percolation threshold for KCl ranged from 58.6 to 61.0% v/v for US and from 26.7 to 42.2% v/v for the traditional tablets. The higher value for ultrasound compacted tablets can be explained by the difficulty of KCl to outcome from a matrix containing insoluble phase that surrounds KCl crystals.

Excipients↗

PubMed2000

Bimodal drug release achieved with multi-layer matrix tablets: transport mechanisms and device design.

The aim of this study was to develop new multi-layer matrix tablets to achieve bimodal drug release profiles (fast release/slow release/fast release). Hydroxypropyl methylcellulose acetate succinate (HPMCAS, type MF) was chosen as a matrix former, because it is water-insoluble at low, and water-soluble at high pH values. Studies focused on the elucidation of the drug release mechanisms from HPMCAS-MF:drug tablets. In 0.1 N HCl the resulting release kinetics can be described using Fick's second law of diffusion, taking into account axial and radial mass transfer in cylindrical geometry. As the diffusion coefficients are found to be constant and the boundary conditions to be stationary, these systems are purely drug diffusion-controlled. In contrast, the dominating mass transport phenomena in phosphate buffer pH 7.4 are more complex. Due to polymer dissolution the resulting matrix structure is time-variant, leading to increasing drug diffusion coefficients and decreasing tablet dimensions, and thus moving boundary conditions. Drug release is affected by water imbibition, drug diffusion and polymer dissolution and is faster compared to 0.1 N HCl. With knowledge of these underlying release mechanisms, multi-layer matrix tablets were developed to achieve bimodal drug release. HPMCAS-MF:drug mixtures were used as tablet cores. As expected, changing the release medium from 0.1 N HCl to phosphate buffer pH 7. 4 after 2 h, lead to a significant increase in drug release. The abruptness of this rate change could be enhanced by adding two drug-free HPMCAS-MF barrier layers (one on each side) to the system. The addition of a fourth, drug-containing and fast disintegrating initial dose layer yielded the desired bimodal drug release patterns. The process and formulation parameters affecting the resulting release rates were investigated using theophylline and acetaminophen as model drugs.

Acetaminophen↗

PubMed2001

Mechanistic modeling of drug release from chitosan coated tablets.

A mechanistic model for drug release from tablets coated with chitosan was derived, assuming that: (1) core tablets are spherical and the drug dissolution is diffusion dependent. (2) In order for the drug release to occur, dissolution medium penetrates through the coated film and leaches out the drug through the film and the lag-time, t(lag) is set for these processes. (3) The coated film itself dissolves and becomes thinner with time. (4) After the film has completely dissipated and the undissolved core tablet becomes naked, drug release proceeds just as the spherical core tablet. Drug release rate was given as a differential equation. Model adaptation was carried out to the release data of propranolol hydrochloride tablets coated with chitosan and kept in different storage conditions. The goodness-of-fit of our model was better than any other conventional equations tested and estimated model parameters were informative.

Chitin↗

PubMed2002

Bioavailability studies on guar gum-based three-layer matrix tablets of trimetazidine dihydrochloride in human volunteers.

Guar gum-based three-layer matrix tablets of a highly water-soluble drug, trimetazidine dihydrochloride, were evaluated for their in vivo release in healthy volunteers in comparison with commercially available conventional immediate release tablets. Six healthy volunteers participated in the study and a two-way crossover design was followed. The plasma concentration of trimetazidine dihydrochloride was estimated by reverse-phase HPLC. The pharmacokinetic parameters were calculated from the plasma concentration of trimetazidine dihydrochloride versus time data. The delayed T(max), decreased C(max) and K(a), unaltered bioavailability, and prolonged t(1/2) and MRT indicated a slow and prolonged release of trimetazidine dihydrochloride from guar gum three-layer matrix tablets in comparison with the immediate release tablet dosage form. The guar gum three-layer matrix tablets of trimetazidine dihydrochloride may be useful in providing constant drug delivery with minimum fluctuations.

Adult↗

PubMed1998

Gamma scintigraphic studies on guar gum matrix tablets for colonic drug delivery in healthy human volunteers.

A novel colon-specific drug delivery system based on a polysaccharide, guar gum, was evaluated by conducting gamma scintigraphic studies using technetium-99m-DTPA as tracer, in six healthy male human volunteers. Scintigraphs taken at regular intervals have shown that some amount of tracer present on the surface of the tablets was released in stomach and small intestine and the bulk of the tracer present in the tablet mass was delivered to the colon. The colonic arrival time of the tablets was found to be 2 to 4 h. On entering the colon, the tablets were found to be degraded in five out of six volunteers thereby releasing a larger amount of the tracer. The study clearly demonstrates that guar gum, in the form of directly compressed matrix tablets, is a potential carrier for colon-specific drug delivery.

Adult↗

PubMed2000

Modified drug release from inert matrix tablets prepared from formulations of identical composition but different organisations.

This paper develops for the first time a concept to modify the release rate of a fixed formulation by changing only the organisation of the mix used to prepare the tablets (ordered mixing). To estimate the influence of the organisation of binary mixes, several mixes of ethylcellulose and niflumic acid of the same composition but different organisation were compacted. The tablet surfaces were examined by energy dispersive X-ray microanalysis before the release experiments. Finally, the cross-sections of the remaining matrix were examined by scanning electronic microscopy. Excipient-excipient and excipient-drug interactions are the major factors influencing the drug release rate from the tablets. In the case of interacting materials, the initial release behaviour depends on the tablet surface presented to the dissolution media. The dissolution properties of the tablets are governed by the percolating material. When the inert excipient is percolating, the release rate increases linearly with the excipient/drug size ratio, whereas when the drug is the only material percolating through the system, its release rate is independent of the size ratio. When both materials are percolating through the system, the release rate is independent of the component particle sizes.

Cellulose↗

PubMed2000

Oral mucosal bioadhesive tablets of pectin and HPMC: in vitro and in vivo evaluation.

The potential of tablets containing 1:4, 1:1 and 4:1 weight ratios of pectin and hydroxypropyl methylcellulose (HPMC) for the sustained release of diltiazem by sublingual administration has been investigated. Measurements of maximum adhesive force to rat peritoneal membrane indicated a satisfactory bioadhesive strength. An in vitro sustained release of diltiazem over 5 h was achieved with bilayer tablets composed of a drug-free ethylcellulose layer in addition to the pectin/HPMC layer containing drug. Plasma concentration-time curves obtained following sublingual administration to rabbits of single and bilayer tablets with 1:1 weight ratios of pectin and HPMC showed evidence of sustained release of diltiazem. Bioavailability of diltiazem was 2.5 times that achieved by oral administration for single layer tablets and 1.8 times for the bilayered tablets.

Adhesives↗

PubMed2001

DC calcium lactate, a new filler-binder for direct compaction of tablets.

In this paper, a directly compressible form of calcium lactate is introduced as a filler-binder for direct compaction of tablets. Calcium lactate is one of the most important calcium sources and has, in comparison with other organic calcium salts, a good solubility and bioavailability. Two different modifications, calcium lactate trihydrate and calcium lactate pentahydrate are described in the main pharmacopoeias. This paper describes that the compaction properties of calcium lactate pentahydrate (Puracal DC) are much better than those of the calcium lactate trihydrate (Puracal TP). Calcium lactate pentahydrate has better compaction properties than dicalcium phosphate dihydrate, even if lubricated with magnesium stearate. Moreover, as a consequence of its crystalline structure, calcium lactate pentahydrate has a low compaction speed sensitivity. This means that, in combination with its excellent flow properties, calcium lactate pentahydrate is a suitable filler-binder in tablets prepared by high-speed compaction. In a number of formulation examples it will be illustrated that tablets containing calcium lactate pentahydrate as main or additional filler-binder have a short disintegration time and a fast drug release. Directly compressible calcium lactate can be considered as a promising excipient in both pharmaceutical tablets and tablets for the nutraceutical market.

Calcium Compounds↗

PubMed2001

The in-vitro porcine adhesion model is not predictive of the esophageal transit of risedronate tablets in humans.

Mucosal damage due to esophageal adhesion of pharmaceuticals is a continued concern to both health care providers and drug manufacturers. As a result of this concern, dosage forms are now being designed to exhibit minimal esophageal adhesion. Previous researchers have used an in-vitro porcine esophageal model to determine the propensity for formulations to adhere to the esophagus as an alternative to human scintigraphy studies. This study used a porcine esophageal adhesion model similar to that used previously to determine the adhesiveness of placebo bisphosphonate formulations. Results are analogous to those obtained by previous researchers, with film-coated tablets showing greater adhesiveness than uncoated tablets. These same tablet formulations were also evaluated previously by a human scintigraphy study, and the results were exactly opposite of those obtained using the in-vitro porcine model. In the human scintigraphy study, the film-coated placebo risedronate tablet had a faster transit time than an uncoated round placebo tablet. In conclusion, the in-vitro porcine esophageal model is not predictive of esophageal transit in man and gamma scintigraphy is the preferred method to evaluate esophageal transit.

Animals↗

PubMed2002

A new method to determine discoloration kinetics of uncoated white tablets occurring during stability testing-an application of instrumental color measurement in the development pharmaceutics.

The tristimulus color coordinates CIELAB and associated parameter Color Intensity (CI) have been shown to be a quantifiable variable for whiteness of uncoated tablets. Whereas any of L*, a* or b* indicates the discoloration of white tablets to a certain degree, it alone cannot reflect the full extent of discoloration. The CI has been defined which is able to describe the discoloration kinetics with acceptable regression coefficients. The evaluation of the CIELAB values from the stability data has shown that the discoloration of the white tablets means an intensification of yellowish or brownish color which is manifested by more or less constant hue angle (hab) values and increasing chroma (Cab*) values. In the view of these data the discoloration kinetics can physically be expressed by the CI. With the CI values the discoloration kinetics can be calculated by linear or polynomial regression with acceptable confidence intervals. The discoloration rates determined under several storage temperatures follow the Arrhenius equation and the activation energy can be estimated for the products. The CI values are unambiguously connected to the visual perception of the corresponding tablets. By means of the discoloration kinetics based on the CI values, it has become possible to statistically determine, the period of time uncoated tablets remain white.

Algorithms↗