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At least 811 records · Page 45Linked to original sources

PubMed2004

Development and evaluation of glyburide fast dissolving tablets using solid dispersion technique.

Glyburide is a poorly water-soluble oral hypoglycemic agent, with problems of variable bioavailability and bio-inequivalence related to its poor water-solubility. This work investigated the possibility of developing glyburide tablets, allowing fast, reproducible, and complete drug dissolution, by using drug solid dispersion in polyethylene glycol. Phase-solubility studies were performed to investigate the drug-carrier interactions in solution, whereas differential scanning calorimetry, X-ray powder diffraction, and infrared spectroscopy were used to characterize the solid state of solid dispersions. The effects of several variables related to both solid dispersion preparation (cofusion or coevaporation technique, drug-to-carrier ratio, polyethylene glycol molecular weight) and tablet production (direct compression or previous wet-granulation, tablet hardness, drug, and solid dispersion particle size) on drug dissolution behavior were investigated. Tablets obtained by direct compression, with a hardness of 7-9 Kp, and containing larger sized solid dispersions (20-35 mesh, i.e., 850-500 microm) of micronized glyburide in polyethylene glycol 6000 prepared by the cofusion method gave the best results, with a 135% increase in drug dissolution efficiency at 60 min in comparison with a reference tablet formulation containing the pure micronized drug. Moreover, the glyburide dissolution profile from the newly developed tablets was clearly better than those from various commercial tablets at the same drug dosage.

Calorimetry, Differential Scanning↗

PubMed2005

A comparison of trehalose dihydrate and mannitol as stabilizing agents for dicalcium phosphate dihydrate based tablets.

This study investigated the possible utility of trehalose dihydrate (TD) as a tablet stabilizing agent. Acetylsalicylic acid was used as the model hydrolyzable drug and dicalcium phosphate dihydrate (DCPD) as the base excipient, because it is well documented that ASA/DCPD tablets are unstable during storage at low temperature and high relative humidity; DCPD is usually combined with mannitol in order to improve tablet stability. Tablets comprising DCPD, 10% ASA, and 0%, 10%, or 20% w/w of TD were prepared by direct compression and stored at 35 degrees C and 82.9% relative humidity for 6 months. Additionally, control tablets with DCPD and ASA, only, or with DCPD, ASA and 20% mannitol, were also evaluated. At predetermined time intervals, formulations were tested for drug content, mechanical, microstructural, and drug dissolution properties. Additionally, thermal analyses and ASA solution stability studies were carried out. Results reveal that both TD and mannitol significantly reduce degradation of ASA included in DCPD-based tablets, but neither effectively protects against the marked decline in tablet mechanical properties on aging. The ASA stabilization effects of TD and mannitol were also observed in solution, indicating an interaction between these sugars and ASA.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2000

Disintegration propensity of tablets evaluated by means of disintegrating force kinetics.

The aim of this work was to measure the disintegrating force concomitantly with tablet disintegration, in order to evaluate the disintegration propensity of tablets. Disintegration and dissolution were measured on tablets containing two poorly soluble drugs (diclofenac sodium or ketoprofen), including different percentages of two disintegrants (Explotab or Ac-Di-Sol). Because of the experimental setup, the disintegrating force measured was the result of the force generated by disintegrant swelling and dissipated by tablet disintegration. The disintegrating force versus time curves had shapes ranging from a skewed distribution curve to a bell-shaped curve, depending on slow or rapid disintegration of tablets, respectively. Interestingly, the shape of the resulting curves was very sensitive to the composition of the tablet. When the disintegrant in the formula was increased, the force-time curve approached the bell-like shape. The disintegration propensity of the tablet can be evaluated by the disintegrating force development during disintegration. The disintegration improvement of the formula can be predicted. The disintegrating force curve allows for the clear identification of the optimal percentage of disintegrant to be used.

Algorithms↗

PubMed1999

Properties of sustained-release tablets prepared by hot-melt extrusion.

The objectives of the present study were to investigate the properties of polyethylene oxide (PEO) as a drug carrier and to study the release mechanism of chlorpheniramine maleate (CPM) from matrix tablets prepared by hot-melt extrusion. During the hot-melt extrusion process, a dry powder blend of drug, polymer, and other adjuvants was fed into the extruder and melted inside the barrel of the machine. The molten mass was extruded through a rod-shaped die and then cut manually into 400-mg tablets. CPM and PEO were shown to be stable under the processing conditions. The molecular weight of the PEO, the drug loading percentage, and the inclusion of polyethylene glycol as a processing aid, were all found to influence the processing conditions and the drug release properties of the extruded tablets. Faster release of CPM from the matrix tablets was observed in acidic medium than in purified water and phosphate buffer (pH 7.4). Drug release from the matrix tablet was controlled by erosion of the PEO matrix and the diffusion of the drug through the swollen gel layer at the surface of the tablets. CPM was dispersed at the molecular level in the PEO matrix at low drug loading level and recrystallization of CPM was observed at high drug loading levels. Hot-melt extrusion was demonstrated to be a viable novel method to prepare sustained-release tablets. PEO was shown to be a suitable polymeric carrier for this process.

Chlorpheniramine↗

PubMed2002

Investigation of excipient type and level on drug release from controlled release tablets containing HPMC.

The purpose of this study was to investigate the influence of excipient type and level on the release of alprazolam formulated in controlled release matrix tablets containing hydroxypropyl methylcellulose (HPMC). Each tablet formulation contained alprazolam, HPMC (Methocel K4MP), excipients, and magnesium stearate. The soluble excipients investigated were lactose monohydrate, sucrose, and dextrose, and the insoluble excipients included dicalcium phosphate dihydrate, dicalcium phosphate anhydrous, and calcium sulfate dihydrate. The similarity factor (f2 factor) was used to compare the dissolution profile of each formulation. The insoluble excipients, especially dicalcium phosphate dihydrate, caused the drug to be released at a slower rate and to a lesser extent than the soluble excipients. Soluble excipients created a more permeable hydrated gel layer for drug release, increased the porosity resulting in faster diffusion of drug, and increased the rate of tablet erosion. Use of binary mixtures of lactose monohydrate and dicalcium phosphate dihydrate produced release profiles of intermediate duration. Rapid drug dissolution was obtained when only 9.1% w/w of lactose monohydrate was present in the tablet formulation. Only when the dicalcium phosphate dihydrate level was sufficiently high (36.5% w/w) was the release rate and extent decreased. It was demonstrated that the type and level of excipient influenced the rate and extent of drug release from controlled release tablets containing HPMC. The release mechanism of alprazolam from each tablet formulation was described by either the Hixson-Crowell cube root kinetics equation or Peppas's equation. However, the different excipient types investigated did not influence the release mechanism of alprazolam from the final tablets.

Alprazolam↗

PubMed2002

Influence of thermal processing on the properties of chlorpheniramine maleate tablets containing an acrylic polymer.

The purpose of this investigation was to determine the effects of thermal processing and post-processing thermal treatment on the release properties of chlorpheniramine maleate (CPM) from matrix tablets containing Eudragit RS PO and triethyl citrate (TEC). CPM tablets containing Eudragit RS PO with and without TEC were prepared by direct compression (DC), high shear hot-melt granulation (HMG), and hot-melt extrusion (HME). X-ray diffraction patterns showed that the CPM was distributed in Eudragit RS PO at the molecular level following HME. The thermogravimetry analysis (TGA) profiles of CPM, Eudragit RS PO, and TEC demonstrated that these materials were thermally stable during both the high shear HMG and HME processes. The tablets were subjected to post-processing thermal treatment by storing the tablets at 60 degrees C in open containers for 24 hr. Tablets prepared by DC showed the highest drug release rate constant of 36.2% hr-1/2. When 4% TEC was incorporated into the formulation, the drug release rate constant for the directly compressed tablets decreased to 32.4% hr-1/2. After high shear HMG and HME of the powder blend containing 4% TEC, the drug release rate constant decreased to 30.8 and 13.8% hr-1/2 for the respective processes. The drug release rate constants for all tablets decreased following post-processing thermal treatment. The reduction in release rate was due to an increase in the intermolecular binding and entanglement between drug molecules and polymer molecules that occurred during thermal processing. Post-processing thermal treatment of the hot-melt extrudates had a minimal effect on the drug release rate since the HME process enhanced the drug and polymer entanglement to a greater extent.

Chlorpheniramine↗

PubMed2003

Prediction of tablet hardness and porosity using near-infrared diffuse reflectance spectroscopy as a nondestructive method.

The main objective of this research is to use the near-infrared diffuse reflectance method to evaluate and quantify the effects of hardness and porosity on the near-infrared spectras of tablets. To develop a model equation, validate the model and test the model predictive ability. Seven theophylline tablet formulations of the same composition but with seven different hardness values (3, 6, 8, 10, 12, 15, and 17 kp) were prepared. Another seven theophylline tablets formulation with seven different porosity values (57.4, 50.3, 41.9, 40.3, 39.9, 37.3, and 35.1%) were prepared. Five placebo tablets formulation with different hardness and porosity values were also prepared. Laboratory hardness and porosity values were compared to near-infrared diffuse reflectance data. Linear regression, quadratic, cubic and partial least square techniques were used to determine the relationship between hardness, porosity and the near-infrared spectras. The results demonstrated that an increase in tablet hardness and a decrease in tablets porosity produced an increase in near-infrared absorbance. Series of model equations depending on the mathematical technique used for regression were developed from the calibration of hardness and porosity data using laboratory equipment vs. the near-infrared diffuse reflectance for each formulations. The results of near-infrared hardness and porosity predictions were very similar to laboratory hardness and porosity tests. The near-infrared diffuse reflectance spectroscopy method is an alternative nondestructive method for measurement of hardness and porosity of tablets.

Cellulose↗

PubMed2004

Effect of hydrodynamic environment on tablets dissolution rate.

The main objective of this research was to develop an experimental method to apply well-defined flow fields to solid dosage forms, to study the rate process underlying tablet dissolution, and to better understand the role of external hydrodynamic condition on mass transfer rate and film thickness during dissolution. Two drugs models, Theophylline (class 1) and Naproxen (class 2), were selected and formulated into conventional tablets containing 105 mg Theophylline or 300 mg Naproxen using the wet granulation method. Tablets were tested for dissolution using both the basket and paddle methods at different rotational speed of 25, 50, 75, and 100 rpm. In general, the paddle method gave higher dissolution rates than the basket method and as the velocity of rotation was increased, drug release was also increased. Six different paddles and a tablet holder were designed and used to test dissolution rate. The rate of dissolution was dependent on the tablet surface area exposed to the dissolution medium, and on the shape, diameter, and area of the paddles used. Theophylline tablets showed increased mass transfer rate and decreased film thickness as basket rotation speed was increased. At 25 rpm, the mass transfer coefficient was 0.684 x 10(-4) cm/sec and film thickness was 12.003 x 10(-2) cm; at 100 rpm, the mass transfer coefficient was 3.884 x 10(-4) cm/sec and film thickness was 2.114 x 10(-2) cm. Paddle values tested at the same speed showed higher mass transfer coefficient and lower film thickness for Theophylline and Naproxen tablets. P values obtained by modification of the Stokes-Einstein equation showed that diffusion is the rate-limiting step to drug release and not mass transfer. This study demonstrated that hydrodynamic condition, type of dissolution testing used, and design of the paddles have an effect on dissolution rate, mass transfer rate, and the film thickness underlying the dissolution process.

Chemistry, Pharmaceutical↗

PubMed2004

Bilayer tablets based on poly (epsilon-caprolactone) and polymethylmethacrilates as controlled-release systems for ruminants.

Rumen-stable devices ensure a protection of active ingredients against chemical degradation and bacterial fermentation processes that occur in the rumen. These systems should also provide postruminal bioavailability and controlled release of the active ingredient. The objective of this study was the preparation of bilayer tablets as rumen-stable delivery systems, designed for the oral administration of active ingredients (folic acid) to ruminants. The tablets are composed of two layers: layer A ("high-density layer") constituted by poly (epsilon-caprolactone) mixed with iron powder and characterized by sufficient density to avoid rumination; layer B ("release layer"), containing folic acid (25 mg), poly (epsilon-caprolactone) or polymethylmethacrylates (Eudragit RS and RL) designed to be rumen-stable and to target a controlled release of folic acid in the intestinal tract. In vitro rumen-protection tests were performed in buffer systems at pH 5.5 and pH 2.0, simulating a ruminal and abomasal environment, to verify the stability of bilayer tablets at these conditions. In vitro release tests were carried out in phosphate buffer at pH 7.4, to study the release behavior of the dosage forms in the intestinal environment. A preliminary in vivo test was carried out with radiographic images made after administration of the tablets to sheep, to evaluate their capacity to be retained in the reticulum-rumen. The amount of iron powder used provides a density of about 2.3 g/cm3 to the whole tablet. The tablets having layer B constituted by poly (epsilon-caprolactone) or Eudragit RS do not disintegrate in buffer media at pH 5.5 and pH 2.0, and they are characterized by a sustained release at pH 7.4. Radiological preliminary tests show that these prepared bilayer tablets are able to be retained in the reticulum-rumen tract of the sheep.

Acrylic Resins↗

PubMed2005

Evaluation of hexagonal boron nitride as a new tablet lubricant.

In this study, hexagonal boron nitride (HBN) was evaluated as a new lubricant for pharmaceutical tablet manufacturing. The other conventional lubricants such as magnesium stearate (MGST), stearic acid (STAC), and glyceryl behenate (COMP) were also tested along with HBN. Tablets were manufactured on an instrumented single-station tablet press to monitor and quantify the lower punch ejection force (LPEF). The force ratio, tablet crushing strength, disintegration time, and thickness were measured. The lubricant film formation and lubricant distribution in tablets were studied using the scanning electron microscopy (SEM) and electron probe micro analyzer (EPMA). Based on the force ratio, a good lubrication was obtained at 1% for MGST and HBN; in contrast, STAC and COMP did not show a good lubrication. After 1%, all lubricants performed well. MGST was found to be the most effective lubricant based on LPEF-lubricant concentration profile. HBN provided a 50% decrease in LPEF at 2% lubricant concentration and was rated as an effective tablet lubricant. HBN was better than either STAC or COMP. Unlike MGST, HBN had no significant prolongation effect on tablet disintegration times.

Boron Compounds↗

PubMed2000

Pharmacokinetics of three formulations of ondansetron hydrochloride in healthy volunteers: 24-mg oral tablet, rectal suppository, and i.v. infusion.

The absolute bioavailability and pharmacokinetics of three formulations of ondansetron hydrochloride 24 mg--an oral tablet, an intravenous solution, and an extemporaneous rectal suppository--were studied. Twelve healthy, nonsmoking volunteers (six men and six women) were given ondansetron in a study with a three-way cross-over design. All subjects received each dosage form on the same day in the following order: oral tablet, rectal suppository, and intravenous infusion. Administrations were separated by one week. Blood sampling times varied, depending on the administration route. Mean absolute bioavailability for the oral tablet and the rectal suppository differed significantly. Absorption of ondansetron was prolonged when it was administered as the rectal suppository. Absolute bioavailability for the 24-mg tablet was similar to that for other tablet strengths in previous studies. All subjects completed the study without significant adverse effects. Absorption of ondansetron from the rectal suppository was prolonged compared with the oral tablet and the i.v. infusion. Bioavailability for the 24-mg suppository formulation was considerably lower than for the 24-mg tablet.

Antiemetics↗

PubMed1995

Substitution of didanosine sachets by chewable tablets: a pharmacokinetic study in patients with AIDS.

We have conducted a pharmacokinetic study of didanosine (ddI), formulated in sachets and in tablets, in patients with acquired immune deficiency syndrome (AIDS). Fifteen subjects received 250 or 167 mg of ddI twice daily as the sachet formulation and used this for at least 1 month. Subsequently, the patients were converted to receive ddI chewable/dispersible tablets (250-mg sachets to 200-mg tablets; 167-mg sachets to 125-mg tablets). Four subjects withdrew because of clinical deterioration or adverse effects. Serial blood samples were collected for pharmacokinetic monitoring during the use of the sachets and after 1 month of use of the tablets. No statistically significant differences were found in the maximum plasma concentration (Cmax), the time to reach Cmax (tmax), the area under the plasma concentration-time curve (AUC), or the terminal elimination half-life (t1/2) between the two formulations. Patients who received low-dose ddI (sachets, 167 mg; tablets, 125 mg) displayed lower plasma concentrations than did the patients receiving high-dose ddI (sachets, 250 mg; tablets, 200 mg), despite an equal weight-normalized dose of ddI in these two groups.

Absorption↗

PubMed2005

A double-blind dose-escalating trial comparing novel mesalazine pellets with mesalazine tablets in active ulcerative colitis.

BACKGROUND: Mesalazine as the treatment standard for ulcerative colitis can be applied in different galenical preparations. AIM: A novel formulation of mesalazine pellets with delayed and prolonged release characteristics was compared with conventional Eudragit L-coated tablets. Furthermore, the effect of mesalazine dose escalation on nonresponders was evaluated in both treatment groups. METHODS: A total of 233 patients with mild to moderately active ulcerative colitis were randomized to receive either mesalazine (1.5 g/day in three doses) as pellets (n = 115) or tablets (n = 118) for 8 weeks. At insufficient response, the dose was increased to 3.0 g. RESULTS: The clinical remission rate (clinical activity index < or = 4) for pellets was 67% vs. 68% for tablets which statistically proved to be not inferior (significance level alpha = 2.5%). In patients without dose increase, the remission rate was 47% (pellets) vs. 42% (tablets). Endoscopic improvement was observed in 80% (pellets) vs. 83% (tablets), and histological improvement in 48% (pellets) vs. 52% (tablets) of patients. CONCLUSIONS: Mesalazine pellets are as effective as tablets in the treatment of mild to moderately active ulcerative colitis. Dose escalation to 3.0 g/day is a valid option for nonresponders to a starting dose of 1.5 g/day.

Adolescent↗

PubMed1981

Terbutaline depot tablets in asthma. A clinical evaluation.

A sustained release preparation of terbutaline sulphate has been formulated (Bricanyl depot tablets) in order to extend the duration and accordingly change the dosage regimen to twice a day. This presentation gives a summary of a clinical trial performed in order to study effect and side effects of terbutaline depot tablets 7.5 mg twice a day compared to terbutaline tablets 5 mg three times a day. Patients suffering from perennial asthma and with daily requirement of asthma medicine were accepted for the study. The trial was a double-blind cross-over, double dummy and randomized. The tablets were given in two consecutive periods of 7 day's duration each. The effect of terbutaline depot tablets was equal to the effect of the ordinary terbutaline tablets. The indication for using depot tablets in the basic treatment of bronchial asthma is a better patient compliance due to medication twice a day. Furthermore in patients with unstable bronchial asthma and in patients with morning dips in PEF the more stable plasma concentration may perhaps keep the patients in a more steady state.

Adolescent↗

PubMed1987

Evaluation of the oesophago-irritant potential of terodiline hydrochloride tablets in three animal models.

The oesophago-irritant potential of terodiline hydrochloride 25 mg tablets was evaluated by use of one acute and two recovery animals models, each documented to be sensitive for predicting local irritant and/or ulcerogenic effects of drugs on the human oesophageal mucosa. Both uncoated and coated terodiline hydrochloride tablets produced slight to moderate oesophageal lesions in cats sacrificed after 4 to 8 hours of tablet exposure, whereas emepronium bromide, a drug associated with oesophageal injury in man, showed moderate to severe oesophago-irritant properties when tested in the same model. No significant oesophageal changes were, however, observed with coated terodiline hydrochloride tablets in cats or pigs subjected to five days of recovery after an initial tablet exposure period of eight and five hours, respectively. The results indicate that the oesophago-irritant effect of terodiline hydrochloride 25 mg tablets is very mild and also transient. Thus no or only a minimal risk of oesophageal irritation after accidental lodging of the tablet in the oesophagus is to be anticipated in patients.

Acute-Phase Reaction↗

PubMed1993

Use of fluoride tablets in childhood: a 10-year prospective study.

Regular and persistent use of fluoride tablets throughout childhood is part of the national population-based preventive strategy and of the individual risk strategy of the Public Dental Health Service in Norway. The purpose of this study was to describe intraindividual stability in use of fluoride tablets in childhood and to analyze change in stability with respect to previous caries risk. Data stemmed from a 10-year prospective study of 231 Norwegian children. Intraindividual stability was described as individual profiles, showing that individual use of fluoride tablets varied substantially over the 10-year period. The significance of previous caries risk for change in use of fluoride tablets was analyzed by logistic regression analysis. The probability of increase in use of fluoride tablets increased significantly with previous caries activity. The results are discussed in light of population strategy and individual risk strategy in the Public Dental Health Service in Norway. Intraindividual variation in use of fluoride tablets over time may reflect the limited individual impact of preventive measures in pursuance of the population strategy. On the other hand, increase in use subsequent to a period of high caries risk indicates that intraindividual change in use of fluoride tablets may be initiated by individual risk strategy.

Child↗

PubMed1986

A study of powder adhesion to metal surfaces during compression of effervescent pharmaceutical tablets.

Effervescent tablets were produced using four different formulations containing citric and/or tartaric acid and sodium bicarbonate with povidone and macrogol 6000. The same formulations were prepared with the addition of 1% sucrose ester powder. The adhesion of each formulation to the metal faces of tableting machine punch tips was determined using electron microscopy, surface roughness measurements and quantification of punch weight variations during tablet production. The basic formulations were inherently adhesive and produced tablets with a weak, porous structure which were qualitatively and quantitatively rougher than conventional, non-effervescent compressed tablets. Both formulations containing tartaric acid produced tablets with a lower surface roughness and with less tendency to stick to tablet punch faces than the two formulations containing citric acid alone. The addition of a water-soluble sucrose ester had a beneficial effect especially on the formulations with inherently high adhesive tendencies.

Adhesiveness↗

PubMed1989

The material tensile strength of convex-faced aspirin tablets.

The material tensile strength of a range of convex-faced tablets, compacted under controlled conditions at pressures of 40 and 320 MPa from a size fraction of acetylsalicylic acid, has been assessed. The calculation of the tensile strength sigma 1, from observed fracture loads obtained in diametral compression testing, is based on the equation derived by Pitt et al (1988), namely: (formula; see text) where P is the fracture load, D is the tablet diameter, t is the overall tablet thickness and W is the central cylinder thickness. The strength of a tablet of a given shape compacted at 320 MPa was between two and four times greater than that of a similar tablet compacted at 40 MPa. For the thicker tablets (W/D greater than or equal to 0.2) the material tensile strength was practically independent of shape. For the thinner tablets (W/D = 0.1) the material tensile strength varied considerably with face-curvature, showing a maximum for each of the two compaction pressures at a D/R value of 0.67.

Aspirin↗