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At least 1,603 records · Page 89Linked to original sources
PubMed2003

Influence of beta-cyclodextrin complexation on carbamazepine release from hydroxypropyl methylcellulose matrix tablets.

The in vitro release profiles of carbamazepine and beta-cyclodextrin either complexed or simply mixed and subsequently incorporated in hydrophilic matrix tablets containing 15 or 30% hydroxypropyl methylcellulose were evaluated. Solubility studies revealed a linear relationship between the increase in carbamazepine solubility and the increase in beta-cyclodextrin concentration. Drying methods (spray-drying and freeze-drying) were used to obtain carbamazepine/beta-cyclodextrin solid complexes in order to prepare tablets. The results demonstrated that matrix tablets containing carbamazepine/beta-cyclodextrin solid complexes displayed faster carbamazepine and beta-cyclodextrin release compared to that containing simple physical mixture. Gelling and matrix formation was impaired in formulation containing 15% hydroxypropyl methylcellulose and spray-dried complex. The comparison of spray-drying and freeze-drying revealed no significant influence of both drying methods on carbamazepine and beta-cyclodextrin dissolution rate when carbamazepine/beta-cyclodextrin complexes were incorporated in 30% hydroxypropyl methylcellulose matrix tablets. The results point to the possibility of modulating carbamazepine release using a hydroxypropyl methylcellulose matrix associated to the drug complexed with beta-cyclodextrin.

Anticonvulsants↗
PubMed1999

Effect of crystallinity of microcrystalline cellulose on the compactability and dissolution of tablets.

Microcrystalline cellulose (MCC) was pulverized with a vibrational rod mill. The degree of crystallinity of MCC decreased from 65.5 to 12.1% with pulverization time due to mechanochemical effect. Pulverized MCCs were compressed at 155.6 MPa using a compression test apparatus, and the two parameters relating to compactability, the B value and yield pressure, were calculated using a Heckel plot. These values were lowered as the degree of crystallinity of MCC became smaller. These results suggest that the crystal region and the amorphous region in MCC particles may be mainly fractured and deformed plastically during compression, respectively. Then the dissolution test was performed for the acetaminophen-MCC (10:90) tablets. Dissolution profiles showed an interesting phenomenon, namely, the dissolution rate of acetaminophen from MCC tablet decreased when the degree of crystallinity of MCC was in the range from 65.5 to 37.6%, however, it increased markedly when the degree of crystallinity of MCC was in the range from 25.8 to 12.1%. The amount of water absorbed into tablets changed in accord with the dissolution rates of acetaminophen from tablets. The dissolution data indicate that drug release can be modified by changing the degree of crystallinity of MCC.

Cellulose↗
PubMed2006

Single-dose sertaconazole vaginal tablet treatment of vulvovaginal candidiasis.

BACKGROUND: Vulvovaginal candidiasis (WC) is a bothersome disease in women. Poor compliance with the continuous use of antifungal vaginal drugs often results in treatment failure. The aim of the present study was to evaluate the efficacy, acceptability, and safety of single-dose sertaconazole vaginal tablet (500 mg) treatment compared with conventional 3-dose econazole vaginal tablet (150 mg) treatment for VVC. METHODS: In this open, randomized, and comparative study, 40 symptomatic patients with VVC confirmed by the smear method were enrolled. Patients in group A were treated with single-dose sertaconazole vaginal tablet and those in group B were treated continuously with econazole vaginal tablet for 3 days. RESULTS: The characteristics of the patients in both groups were comparable and without statistical difference. Group A showed a significantly better clearance rate for candidiasis than group B (100% vs. 72.2% on day 7, p = 0.013; 100% vs. 77.8% on day 14, p = 0.030), based on smear method results. Group A showed a more rapid response for symptom relief than group B on day 7, but there was no difference in overall symptom relief between group A and group B on day 14. CONCLUSION: Single-dose sertaconazole proved to be a more convenient and symptom-relieving treatment for VVC. The advantages of such management are worthy of further study in women with relapse VVC.

Administration, Intravaginal↗
PubMed2003

Olanzapine orally disintegrating tablets in the treatment of acutely ill non-compliant patients with schizophrenia.

The objective of this study was to determine if the orally disintegrating tablet formulation of olanzapine, Zyprexa Zydis, would facilitate antipsychotic medication compliance in acutely ill, non-compliant patients. Eighty-five acutely ill patients with schizophrenia or schizoaffective disorder who met medication non-compliance criteria received open-label olanzapine orally disintegrating tablets (1020 mgd) for up to 6 wk. Improvement in medication compliance was assessed using various rating scales to measure changes in psychopathology, medication-taking and compliance attitudes, and nursing care burden. Safety variables were also measured. Significant improvement from baseline was demonstrated in the Positive and Negative Syndrome Scale total score at Week 1 and subsequently (p0.001). Significant improvement from baseline was also seen in various scales measuring medication compliance, attitude, and nursing care burden (p0.05). Olanzapine orally disintegrating tablets were well-tolerated. Olanzapine orally disintegrating tablets may benefit acutely ill, non-compliant schizophrenic patients by facilitating acceptance of active antipsychotic drug therapy.

Acute Disease↗
PubMed1997

Nondestructive viscoelastic analysis of anisotropy in compressed tablets.

A nondestructive procedure for determining anisotropy levels in compressed tablets was developed based on dynamic stress/strain measurements of viscoelasticity in the axial and radial directions. An instrument was designed and built capable of 10 nm resolution of strain and operating over the frequency range 1-64 Hz. Tablets of 11 pharmaceutical excipients and drugs, representing both plastic and brittle materials, were found to behave as three-parameter viscoelastic solids in both the axial and radial directions. Elastic and viscous parameters were computed, based on frequency dependence over the range studied, and were found to differ greatly in the axial and radial directions. Degrees of anisotropy, defined as the ratio of the uncoupled spring parameters in the radial vs the axial direction, were found to range from 2- to 12-fold over the materials studied. These levels of anisotropy are thought to be typical of tablets manufactured in a rotary press under normal conditions. Measurements of this type can be easily made routinely as a further means of quality control and reflect an important feature of the internal structure of compressed tablets.

Anisotropy↗
PubMed1997

Intravenous and oral pharmacokinetic evaluation of a 2-hydroxypropyl-beta-cyclodextrin-based formulation of carbamazepine in the dog: comparison with commercially available tablets and suspensions.

Complexation of carbamazepine with 2-hydroxypropyl-beta-cyclodextrin was performed to provide improved formulations of this widely used antiepileptic drug. Based on this approach, liquid dosage forms were configured for both parenteral and oral use. Intravenous administration of an aqueous carbamazepine x 2-hydroxypropyl-beta-cyclodextrin (CBZ x HPbetaCD) complex at a CBZ dose of 20 mg/kg was well tolerated and generated high initial drug levels that fell monoexponentially as a function of time, yielding a plasma elimination half-life of 38 min. Oral studies were completed with three preparations: a commercially available tablet and suspension, as well as a CBZ x HPbetaCD oral solution. Oral administration of tablets gave erratic and slow absorption, leading to maximum CBZ concentrations (C(max)) of <2 microg/mL, which were manifested only at 2.5 h after drug dosing. The absolute bioavailability of CBZ from the tablets was approximately 25%. Both the suspension and CBZ x HPbetaCD solution gave a significantly improved profile. Thus, the liquid oral dosage forms approximately doubled the oral bioavailability of CBZ compared with the tablets.

2-Hydroxypropyl-beta-cyclodextrin↗
PubMed1998

Design and evaluation of an osmotic pump tablet (OPT) for prednisolone, a poorly water soluble drug, using (SBE)7m-beta-CD.

PURPOSE: The purpose of this study was to develop a controlled-porosity osmotic pump tablet (OPT) for poorly water soluble drugs using a sulfobutyl ether-beta-cyclodextrin, (SBE)7m-beta-CD or Captisol, which acted as both a solubilizer and as an osmotic agent. METHODS: Prednisolone (PDL) was chosen as a model drug for this study. The release of PDL from osmotic pump devices and tablets was studied. In vivo absorption of PDL from OPT was evaluated in male beagle dogs. RESULTS: PDL release from the osmotic pump tablet with (SBE)7m-beta-CD was complete. Another cyclodextrin, hydroxypropyl-beta-cyclodextrin (HP-beta-CD), and a sugar mixture of lactose and fructose resulted in incomplete release. Although PDL release from the OPT with (SBE)7m-beta-CD and the sugar formulation displayed mainly zero-order release characteristics, the tablet utilizing HP-beta-CD showed apparent first-order release characteristics. An in vivo absorption study in dogs correlated very well with the in vitro release profiles using the Japanese Pharmacopoeia dissolution method. CONCLUSIONS: The present results confirm that (SBE)7m-gamma-CD can serve as both the solubilizer and the osmotic agent for OPT of PDL, and modify the input rate of PDL without compromising oral bioavailability.

Absorption↗
PubMed1997

Theory of force transducer design optimization for die wall stress measurement during tablet compaction: optimization and validation of split-web die using finite element analysis.

PURPOSE: 1) To illustrate how computer aided engineering stress analysis can be used to improve the transducer design process for tablet press instrumentation; 2) to use these optimal design procedures for the geometric optimization of a cylindrical, segmented, and a novel split-web die design. Discussion includes the selection of optimal die wall thickness, segment cutting angle, strain gage placement, Wheatstone bridge configuration, and the influence of tablet height and position within the die on signal output. METHODS: Stress analysis was done with a finite element analysis (FEA) software package running on a personal computer. RESULTS: For the segmented die, the admissible range of die wall thicknesses depends upon cutting angle; the signal output is non-linear because the stress distribution in the die wall is influenced by tablet height and position within the die. For the split-web die, the optimal configuration consists of a 1/8 in. sensing web with a strain gage located at the peak of the sensing-web arch. This prototype had a linear calibration curve (r2 = 0.999) with no hysteresis. Radial versus axial stress transmission curves for: starch and sodium chloride were consistent with literature data. CONCLUSIONS: Finite element analysis (FEA) is a useful numerical tool for the systematic optimization of tablet press instrumentation. By enclosing the sensing web of a three layered die design in a cylinder, the split-web design can be directly mounted without modification of the die table.

Drug Design↗
PubMed1991

Correlation of the gastric emptying of nondisintegrating tablets with gastrointestinal motility.

The aim of the present study was to correlate the gastric emptying (GE) of nondisintegrating tablets with changes in gastrointestinal (GI) motility. Eight, healthy, male subjects each received 5 x 7-mm radiolabeled tablets, a radiolabeled meal, and a radiotelemetry capsule (RTC). Transit of the radiolabeled formulations was followed by gamma scintigraphy and the RTC detected contractile activity in the GI tract. The study demonstrated that 7-mm tablets can empty from the fed stomach, prior to the onset of interdigestive activity. Those tablets that were not emptied during fed activity were retained through the period of quiescence associated with the onset of the migrating myoelectric complex (MMC) and left the stomach during contractions associated with phase 2 and 3 activity. The RTC was retained in the stomach and was emptied only by large phase 3 contractions commonly termed the "housekeeper" wave. However, in one subject, the RTC was retained in the stomach for over 12 hr, during which time three distinct phase 3 complexes were monitored.

Adult↗
PubMed1988

Kinetics of release from enteric-coated tablets.

Controlled and localized release of drugs in the intestine can be achieved by enteric coating. The design of enteric-coated tablets has so far remained empirical, in part because of the lack of a quantitative description of the drug release kinetics. In this paper, a mathematical model is presented that describes the dissolution of the polymer coating and release kinetics of weakly acidic drugs from enteric-coated tablets in buffered media. This model can also be used to predict the time of onset of core disintegration. The model assumes that the release rate is limited by diffusion, and furthermore, all the reactions are considered as reversible and instantaneous. Dissolution and reaction are assumed to take place in the polymer layer and a hypothetical stagnant liquid film adjacent to the polymer layer (the classical film theory approach). The dissolution of the enteric coating is found to depend on the intrinsic solubilities and pKa's of the drug and polymer and the medium properties. The release rate of the drug is found to depend on the intrinsic solubilities and pKa's of drug and polymer, the medium properties, i.e., pH and buffer capacity, and a mass transfer coefficient. Explicit relationships between the release rates and all these factors are derived. Successful prediction of experimental data indicates that the model provides an adequate description of release from enteric coated tablets. Limitations of the model and its potential application to the design of appropriate in vitro testing conditions and to the formulation of enteric coated tablets are also discussed.

Buffers↗
PubMed1996

Structure and behavior in hydrophilic matrix sustained release dosage forms: 4. Studies of water mobility and diffusion coefficients in the gel layer of HPMC tablets using NMR imaging.

PURPOSE: The purpose of this study was to characterise the water mobility in the gel layer of hydrating HPMC tablets. Water mobility in the gel layer of different HPMCs was studied. METHODS: NMR imaging, a non-invasive technique, has been used to measure the spatial distribution of self-diffusion coefficient (SDC) and T2 relaxation times across the gel layer. RESULTS: It has been shown that there is a water mobility gradient across the gel layer of HPMC tablets. Although SDC and T2 relaxation times in the outer parts of the gel layer approached that of free water, in the inner parts they decreased progressively. Water mobility and SDC in the gel layer of different HPMCs appeared to vary with degree of substitution of the polymer and the lowest values were obtained across the gel layer of K4M tablets. CONCLUSIONS: Water mobility varies across the gel layer of hydrating HPMC tablets and it is dependent on the degree of substitution of the polymer.

Chemical Phenomena↗
PubMed1999

Solid state assay of ranitidine HCl as a bulk drug and as active ingredient in tablets using DRIFT spectroscopy with artificial neural networks.

PURPOSE: A new, simple, sensitive and rapid method was developed to analyse the polymorphic purity of crystalline ranitidine-HCI as a bulk drug and from a tablet formulation. METHODS: Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy was combined with Artificial Neural Networks (ANNs) as a data modelling tool. A standard feed-forward network, with backpropagation rule and with single hidden layer architecture was chosen. Reduction and transformation of the spectral data enhanced the ANN performance and reduced the complexity of the ANNs model. Spectral intensities from 1738 wavenumbers were reduced into 173 averaged spectral values. These 173 values were used as inputs for the ANN. Following a sensitivity analysis the number of inputs was reduced to 30, or 35, these being the input windows which had most effect on the output of the ANN. RESULTS: For the bulk drug assay, the ANN model had 30 inputs selected from a sensitivity analysis, one hidden layer, and two output neurons, one for the percentage of each ranitidine hydrochloride crystal form. The model could simultaneously distinguish between crystal forms and quantify them enabling the physical purity of the bulk drug to be checked. For the tablet assay, the ANN model had 173 averaged spectral values as the inputs, one hidden layer and five output neurons, two for the percentage of the two ranitidine hydrochloride crystal forms and three more outputs for tablet excipients and additives. The ANN was able to solve the problem of overlapping peaks and it successfully identified and quantified all components in tablet formulation with reasonable accuracy. CONCLUSIONS: Some of the advantages over conventional analytical methods include simplicity, speed and good selectivity. The results from DRIFT spectral quantification study show the benefits of the neural network approach in analysing spectral data.

Anti-Ulcer Agents↗
PubMed2003

Patient experiences with the performance of tablet score lines needed for dosing.

OBJECTIVE: The aim of this study was to measure the experience of patients with score line tablets where breaking was necessary for dosing. METHOD: In three community pharmacies in the Netherlands, patients were asked about their experiences with the functioning of the score line. The survey was restricted to scored tablets that had to be broken to obtain the prescribed dose. It was also asked what actions were taken by the patient when breaking problems were encountered. RESULTS: Of all the score line prescriptions included in the study, 36% received a negative evaluation by the patient. The main negative experiences were related to loss of mass after breaking the tablets and difficulty in breaking, reported in 32% and 15%, respectively, of the prescriptions included in the study. In only 28% of the negative experiences had this been reported back to the pharmacy. CONCLUSION: Many patients experience an unsatisfactory performance of tablets with score lines. Improvement will need a combination of technically better score lines and the alertness of the dispensing pharmacy for breaking problems.

Adult↗
PubMed2004

Screening for esophageal luminal narrowing--a magnetic disc tablet as a bolus challenge: preliminary report.

Narrowing of the esophageal lumen often exists for months before being noted by the patient. Screening tests for such lesions would be useful, if applicable to office use. A magnetic disc tablet (14 mm in diameter and 5 mm thick) was fashioned by hand using dental acrylic material to enclose the magnet with a smooth watertight sheath. A magnetic detector was held on the anterior abdominal wall 2.5 cm below the xiphoid cartilage and 2.5 cm to its left. A significant change in reading indicated that the tablet had reached the cardia of the stomach. The magnetic tablet was readily detected in 11 patients without organic narrowing. Our method attempts to detect narrowing of the esophageal lumen by use of a magnetic disc tablet. Perhaps this will be of clinical usefulness in detecting esophageal disease before symptoms become apparent.

Administration, Oral↗
PubMed2004

Improved tableting properties of p-hydroxybenzoic acid by water of crystallization: a molecular insight.

PURPOSE: To understand the influence of water in the crystal structure on the compaction properties of otherwise structurally similar crystals, p-hydroxybenzoic acid anhydrate (HA) and the monohydrate (HM) were used as model compounds. METHODS: Bulk powder of HM was prepared by exposing HA powder to 97% relative humidity at 23 degrees C. Each powder, HA or HM, was uniaxially compressed and triaxially decompressed under various pressures to form square-faced tablets. The tensile strength and porosity of the tablets were measured. RESULTS: Incorporation of water into the crystal lattice results in greater tablet strength and larger reduction in volume for HM crystals than for HA crystals. Both HA and HM crystals contain hydrogen-bonded, zigzag-shaped layers that lie parallel to the (401) plane. When HA crystals are compressed, the zigzag-shaped layers mechanically interlock, inhibiting slip and reducing plasticity. However, water molecules in the HM crystals assume a space-filling role, which increases the separation of the layers. This effect allows easier slip between layers and provides greater plasticity of HM crystals, which increases the interparticulate bonding area under the same compaction pressure. However, the water molecules in the HM crystals increase their lattice energy by forming a three-dimensional hydrogen-bonding network. The greater bonding strength that results is reflected in greater tensile strength of HM compacts at zero porosity. CONCLUSIONS: The presence of water molecules in the crystal structure of p-hydroxybenzoic acid facilitates plastic deformation of HM crystals, thereby enhancing their bonding strength and giving much stronger tablets than of HA crystals.

Chemical Phenomena↗
PubMed1986

Variability of steady-state digoxin kinetics during administration of tablets or capsules.

An encapsulated solution of digoxin has been repeatedly shown to have greater bioavailability than tablet forms of the drug. It is predicted that such a preparation would show reduced within- and between-patient variability in absorption, as most studies in normal subjects have shown reduced intersubject variation with the capsule. We tested inter- and intrapatient variability during 4-week periods of dosing with digoxin capsules and tablets in 28 subjects with cardiac disease. In the overall group there were no significant differences between the formulations at steady state in between-patient variability in trough serum digoxin concentrations or 24-hour urinary digoxin excretion. Within-patient variability in urinary digoxin excretion was somewhat lower for the capsules. In a subgroup of six patients who excreted significant amounts of cardioinactive bacterial metabolites (digoxin reduction products [DRP]), the mean (+/- SD) percent urinary DRP excretion was less (p less than 0.05) during capsule (20.5% +/- 15.1%) than tablet (34.4% +/- 10.9%) dosing. Within-patient variability in urinary DRP excretion was much greater after tablets than capsules. Certain subgroups of patients should benefit from the enhanced bioavailability of digoxin capsule preparations.

Absorption↗
PubMed1989

Time to stop counting the tablets?

We attempted to assess compliance using both a pharmacologic indicator (low-dose phenobarbital) and a return tablet count in 225 patients who were taking part in three separate studies. There were 216 patients (96%) who kept a follow-up appointment after 28 days; 161 patients appeared to have good compliance (90% to 109%) by return tablet count. Of these 161 patients, 51 (32%) had plasma phenobarbital concentrations (corrected for dose and weight) that were less than 90% of the lowest value previously found in normal volunteers, which suggested poorer compliance. When compared with the age-related volunteer values, 77 (48%) had values that were less than 90% of the lowest volunteer value. There were 6 of 10 patients with apparently excessive (greater than or equal to 110%) compliance by return tablet count and 4 of 12 who failed to return their container who also had phenobarbital concentrations that were less than 90% of the lowest volunteer value. We concluded that return tablet count grossly overestimates compliance.

Drug Therapy↗
PubMed1998

Quantification of paracetamol in intact tablets using near-infrared transmittance spectroscopy.

Production batch samples of paracetamol tablets and specially prepared out-of-specification batches covering the range 90-110% of the stated amount (500 mg) were analysed by the BP official UV assay and by NIR transmittance spectroscopy. NIR measurements were made on 20 intact tablets from each batch, scanned five times each (10 min measurement time per batch) over the spectral range 6000-11,520 cm-1. An average spectrum was calculated for each batch. Partial least squares (PLS) regression models were set up using a calibration set (20 batches) between the NIR response and the reference tablet paracetamol content (UV). Various pre-treatments of the spectra were examined; the smallest relative standard error of prediction (0.73%) was obtained using the first derivative of the absorbance over the full spectrum. Only two principal components were required for the PLS model to give a good relationship between the spectral information and paracetamol content. Applying this model to the validation set (15 batches) gave a mean bias of -0.08% and a mean accuracy of 0.59% with relative standard deviations of 0.75 and 0.44%, respectively. The proposed method is non-destructive and therefore lends itself to on-line/at-line production control purposes. The method is easy to use and does not require a knowledge of the mass of the tablets.

Acetaminophen↗