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1.
The main aims of the present study were to establish an in vitro/in vivo correlation for multiple-unit capsules of paracetamol by means of statistical prediction models and to investigate the effect of a number of in vitro variables on the discussion rate of paracetamol from the formulation. A fractional factorial screening design was used to investigate the effects of the variables agitation, pH, osmolality, viscosity, and the presence of bile salt on the dissolution rate of paracetamol. The effects were evaluated in two separate partial least-squares models, in which the responses were expressed as the cumulative percentage of paracetamol dissolved at specified time-points (model I) and as the shape (beta) and scale (eta) parameters according to the Weibull function (model II). It was concluded that agitation and viscosity had significant effects on the dissolution rate of paracetamol. Statistical models based on the responses from models I and II were then used to predict the in vitro conditions most closely correlated with the in vitro dissolution of paracetamol after administration of the formulation to 10 healthy volunteers. The predicted optimal in vitro conditions were similar for the two models and not too far from what is expected from the gastrointestinal tract. The experimental verification of the in vitro conditions showed that both models were equally good, and contributed to high degrees of correlation with the in vivo dissolution behavior of the formulation during 9 hr. The relationships obtained when plotting the percentage dissolved in vitro versus in vivo were y = 1.1x (r2 = 0.98) and y = 1.1x (r2 = 0.94) for models I and II, respectively. Based on these results, it is difficult to state a preference for one of the models. Finally, the use of statistical prediction models to develop critical in vitro tests is a successful approach in the establishment of associations between dissolution behavior in vitro and in vivo for oral extended-release systems.  相似文献   

2.
The rate and extent of dissolution of various approved marketed carbamazepine (CBZ) tablets exposed to 33, 52, 75, and 97% relative humidities at both room temperature and 40 degrees C, and saturated water vapor at room temperature were compared to fresh unstressed tablets. The dissolution data indicate that exposure of CBZ tablets to high humidity and temperature can have a profound effect on tablet disintegration and dissolution. The dissolution rates of some batches of CBZ products exposed to 97% humidity at 40 degrees C or saturated water vapor at room temperature were drastically reduced in only 6-7 days.  相似文献   

3.
The in vivo performance of multiparticulate sustained-release diltiazem preparations [HER-SR(A,B,C)] coated with water-insoluble polymer (ethylcellulose), to control the in vitro dissolution rate, was evaluated in dogs. With a decrease in dissolution rate, HER-SR maintained sustained-release characteristics, although the bioavailability decreased slightly. The bioavailability of HER-SR(A,B,C) was comparable with that of a conventional diltiazem tablet (HER). Plasma diltiazem concentrations for the HER-SR preparations were analyzed with a two-fraction absorption model and the pharmacokinetic characteristics were discussed. From the results, it was considered that HER-SR(B) preparation had desirable pharmacokinetic characteristics as sustained-release diltiazem preparations. The absorption site of the slow-release component of HER-SR(B) in the gastrointestinal tract was examined. Almost all of the component had reached the colon within 5 h of administration, the diltiazem content remaining in the component being approximately 60% of the initial amount. Thus, it was shown that the HER-SR(B) preparation had particular absorption characteristics that resulted in the colon being the part of the gastrointestinal tract most receptive to its release. In vivo release profiles of diltiazem from the HER-SR(B) preparation were calculated by the Wagner-Nelson method, and in vitro and in vivo release profiles of HER-SR(B) were further analyzed with a two-fraction release equation. A close correlation of in vitro and in vivo release profiles of HER-SR(B) was found.  相似文献   

4.
A common belief is that one tablet or suppository containing, e.g. 100 mg of a drug can be substituted, without any changes in the therapeutic effect, with two units of the same brand containing 50 mg of the drug. In the present study a single dose of paracetamol was administered to healthy volunteers as (a) two tablets of 500 mg, (b) two suppositories of 500 mg, and (c) one suppository of 1000 mg. There were statistically significant differences in all bioavailability parameters (t(max), C(max) and AUC) between the three treatments. The relative bioavailability of the 500 mg suppositories was 77% and that of the 1000 mg suppositories 66%. The absorption rate from suppositories was markedly lower than from the tablets. Especially low absorption rate was obtained with the suppository of 1000 mg. The two strengths, although having the same trade name, were not therefore bioequivalent.  相似文献   

5.
Enteric coated dexchlorpheniramine maleate (DCPA) tablets and pellets with varying coating thickness were subjected to several in vitro tests after irradiation by thermal neutrons in a flux of 1. 1 x 10(13) n cm-2 s-1 for 2, 4 or 15 min. The appearance of the tablet formulation changed extensively after exposure of the tablets to pile radiation. The irradiation caused the film to loosen from the surface of the core, indicating the generation of gases during the irradiation process. Already after irradiating the tablets for 2 min the disintegration and dissolution behaviour were significantly changed. The extent of tablet damage increased with increasing time of exposure and increasing thickness of the coating. Compared with the tablet formulation, the cores could resist a larger amount of irradiation since dissolution behaviour of the cores was only affected after 15 min of irradiation. This indicates that the irradiation procedure initially affects the coating of the formulation. Although the dissolution behaviour of the pellet formulations changed significantly after the irradiation procedure, the changes were too small to be attributed exclusively to radiation damage.  相似文献   

6.
Furosemide is a problematic drug in a prolonged-release product because its absorption is site specific, taking place mainly in the upper parts of the alimentary tract. The aim of the study reported here was to develop prolonged-release furosemide formulations for dogs. The type of preparation selected was a hydroxypropyl methylcellulose (HPMC) matrix tablet. Evaluation was based on dissolution studies, on in vivo disintegration studies in the canine stomach and on bioavailability studies in Beagle dogs. The variables tested were the viscosity grade of the polymer, the amount of polymer and presence or absence of an alkaline compound (potassium carbonate) in the formulation. When potassium carbonate was included, furosemide was absorbed so slowly that drug administration once daily would give plateau drug plasma concentrations, even though the elimination half-life of furosemide is only about one hour. In vitro dissolution tests gave a wrong indication of the in vivo behaviour of the products. Thus, in vivo studies are important from the very beginning in the development of new drug products for dogs.  相似文献   

7.
Whether a rapid elevation of serum gliclazide concentration in human subjects can be achieved through an acceleration of dissolution of gliclazide from a formulation was examined. A soft gelatin capsule containing PEG 400, PEG 4000, Tween 20 and glycerin was prepared as a formulation that may accelerate dissolution of gliclazide. The in vitro dissolution of gliclazide at pH 7.2 was identical for the soft capsule and conventional tablets, Diamicron and Diberin. However, at pH 1, 2 and 4.0 the dissolution from the soft capsule was more rapid compared to the tablets. When bioavailability parameters were compared following oral administration of the soft capsule and Diamicron to 16 healthy Korean male subjects, the parameters representing the amount of adsorption (i.e. the area under the serum gliclazide concentration vs. time curve up to 24 h, AUC24, and the peak serum concentration Cmax) were not statistically different for both formulations. However, the time required to reach the peak (Tmax) was significantly shorter for the soft capsule than for the Diamicron. Our results, therefore, indicate that a rapid elevation of serum gliclazide concentration following oral administration of a formulation can be achieved by accelerating the in vitro dissolution of gliclazide from the formulation into the acidic buffers. Thus, the rate of gastrointestinal absorption of gliclazide appears to be dependent on its in vivo dissolution rate in gastric fluid. A soft capsule containing a PEG 400 suspension of gliclazide appears to be an appropriate formulation for accelerating the dissolution.  相似文献   

8.
PURPOSE: This study was undertaken to examine the effects of mechanical destructive forces on drug release from controlled release (CR) dosage forms in vitro and in vivo and their colonic release, using two CR tablets of acetaminophen A and B, showing slower and faster erosion rates, respectively. METHODS: In vitro release rates were determined by several official methods. Tablets were administered to healthy volunteers under fasting and fed conditions. RESULTS: Both tablets showed similar release rates under mild destructive conditions (e.g., paddle method at 10 rpm) but CR-B showed faster release under highly destructive conditions (e.g., rotating basket method at 150 rpm), where the tablet was eroded. The in vivo release from CR-B was faster than from CR-A, possibly because of enhanced erosion. The variable in vivo release from CR-B indicated large inter-subject differences in destructive GI forces. The fastest in vivo release from CR-B among individuals was approximated by the in vitro dissolution determined by destructive methods such as the rotating basket at 150 rpm. The slowest in vivo release from tablets A and B was lower than the dissolution by the paddle method at 10 rpm. The release from both tablets was markedly reduced at 3-4 hrs after dosing irrespective of feeding conditions which can be attributed to release inhibition in the colon. CONCLUSIONS: Effects of GI destructive forces on the tablet erosion and the release inhibition in the colon must be considered in the development of CR dosage forms.  相似文献   

9.
The ground mixture of phenytoin and microcrystalline cellulose was prepared by grinding in a vibrational ball mill. The X-ray diffraction patterns indicated the amorphous nature of the ground mixture. Comparative studies were made concerning the in vitro dissolution and in vivo absorption of fine phenytoin powder, phenytoin sodium powder, and the ground mixture. The ground mixture showed a greater dissolution rate than the fine powder and attained supersaturation in the pharmacopeial disintegration media at pH 1.2 and 7.4. In vivo absorption studies of each preparation were carried out in five subjects, using a crossover design, by measuring the urinary excretion rate of a main metabolite, 5-(p-hydroxyphenyl)-5-phenylhydantoin. The blood levels of phenytoin and the corresponding urinary excretion patterns of the metabolite were determined in two subjects. The ground mixtures significantly improved the bioavailability of phenytoin. The drug was completely and rapidly absorbed after oral administration of the ground mixture. The vibrational ball milling technique for a poorly water-soluble drug with microcrystalline cellulose provides a promising way of improving the in vivo drug absorption.  相似文献   

10.
The purpose of this study was to evaluate the effect of formulation and processing changes on the dissolution and bioavailability of propranolol hydrochloride tablets. Directly compressed blends of 6 kg (20,000 units) were prepared by mixing in a 16-qt V blender and tablets were compressed on an instrumented Manesty D3B tablet press. A half-factorial (2(5-1), Resolution V) design was used to study the following variables: filler ratio (lactose/dicalcium phosphate), sodium starch glycolate level, magnesium stearate level, lubricant blend time, and compression force. The levels and ranges of the excipients and processing changes studied represented level 2 or greater changes as indicated by the Scale-up and Post Approval Changes (SUPAC-IR) Guidance. Changes in filler ratio, disintegrant level, and compression force were significant in affecting percent drug released (Q) in 5 min (Q5) and Q10. However, changes in magnesium stearate level and lubricant blend time did not influence Q5 and Q10. Hardness was found to be affected by changes in all of the variables studied. Some interaction effects between the variables studied were also found to be significant. To examine the impact of formulation and processing variables on in vivo absorption, three batches were selected for a bioavailability study based on their dissolution profiles. Thirteen subjects received four propranolol treatments (slow-, medium-, and fast-dissolving formulations and Inderal 80 mg) separated by 1 week washout according to a randomized crossover design. The formulations were found to be bioequivalent with respect to the log Cmax and log AUC0-infinity. The results of this study suggest that (i) bioavailability/bioequivalency studies may not be necessary for propranolol and perhaps other class 1 drugs after level 2 type changes, and (ii) in vitro dissolution tests may be used to show bioequivalence of propranolol formulations with processing or formulation changes within the specified level 2 ranges examined.  相似文献   

11.
This report describes results of a collaborative study in which samples of the 40-mg strength of furosemide tablets were evaluated following a common protocol based on British (BP), European (Ph. Eur.), and US Pharmacopoeial (USP) specifications. Several tests, including identification, uniformity of mass, and dissolution, were performed. In total, excluding Lasix lots, results for 162 lots obtained from 115 manufacturers or suppliers were submitted. Also, 23 laboratories identified and submitted data for 34 lots of Lasix products available in their countries. There were no reported abnormalities in the physical test requirements of the products analyzed. The summaries (n, mean, and 95% CI) of the assay results for the "standard sample" (a common sample), Lasix lots from participating countries, and for all other furosemide products, respectively, are as follows: 30, 99.8%, 96-104; 33, 100.0%, 94-106; and 162, 99.6, 94-105. About half (approximately 62%) of the reported uniformity of mass results based on tablet weights were in the range 150-175 mg/tablet. However, there appears to be notable variability in tablet weights that would result in significant differences in the ratios (0.14 to 0.40) of active ingredient to excipient. The reported disintegration times ranged from 0 (instantaneous) to 18 min, with most less than 1 min. The drug dissolution testing was conducted with phosphate buffer at pH 5.8 (USP recommended). Another test was conducted with acetate buffer at pH 4.6 (noncompendial). There appears to be remarkable similarity in overall percentage of drug release from the three types of products (standard sample, Lasix lots, and other products). Although apparently there is a very wide spread in dissolution characteristics of the products tested, the analyses of variance did not detect differences among the products tested and, to this extent, would not indicate differences in bioavailability characteristics for most of these products. It is observed that about 20-38% of the variability in dissolution testing is not product related (i.e., it is from the dissolution testing itself), while the remaining 62-80% variability is product related (manufacturing, formulation, etc). The results of this multinational collaborative study showed that most of the furosemide products available in different countries met the required pharmaceutical quality standards, including drug-release characteristics. Based on an extensive statistical analysis, the main concern from the study was that the high variability in drug dissolution testing would require wide tolerance standards (e.g., pharmacopoeial standards). This may result in lack of needed discriminating ability of the test in revealing the impacts of formulation and manufacturing changes on in vitro, and perhaps in vivo, drug-release characteristics.  相似文献   

12.
The effect of epidural infusions containing fentanyl on maternal gastric emptying in labour was examined using the rate of paracetamol absorption. Women were randomly allocated to receive one of two epidural infusions, bupivacaine 0.125% alone or bupivacaine 0.0625% with fentanyl 2.5 micrograms.ml-1 at a rate of 10-12 ml.h-1. Paracetamol 1.5 g was given orally to women after either 30 ml of the infusion solution had been given (mean time 2.5 h, study A) or 40-50 ml (mean time 4.5 h. study B). Six venous blood samples were taken over the next 90 min for measurement of plasma paracetamol concentration. There were no significant differences in maximum plasma paracetamol concentration, time to maximum paracetamol concentration and area under the concentration-time curve between the two groups for study A. In study B the time to maximum plasma paracetamol concentration was significantly delayed in women receiving > 100 micrograms fentanyl compared with controls (p < 0.05). We conclude that the dose of fentanyl that may delay gastric emptying when given by epidural infusion is greater than 100 micrograms.  相似文献   

13.
The flux in rat hepatic ratio of adenosine triphosphate levels to adenosine diphosphate levels (ATP/ADP) during the onset and progression of paracetamol-induced cell injury both in vivo and in vitro were investigated and compared. Leakage of lactate dehydrogenase (LDH) and potassium (K+), and mg water/mg dry weight quantified cell injury. ATP and ADP levels were determined using the luciferin-luciferase bioluminescence assay. For in vitro studies, liver slices obtained from phenobarbitone-induced rats were exposed to 10 mM paracetamol for 120 min (T0-T120) and, then incubated without paracetamol up to a further 240 min (T120-T360). For in vivo studies, groups of four phenobarbitone-induced rats received i.p. injections of 800 mg/kg paracetamol. ATP/ADP ratios fall upon exposure to paracetamol both in vitro and in vivo. However, unlike the in vitro situation where the fall in ATP/ADP ratios precedes and accompanies the progression of cell injury, the in vivo fall in ATP/ADP ratios is shown to occur as cell injury measurements begin to recover to control levels. However, despite these differences classic paracetamol-induced centrilobular necrosis is observed to occur both in vitro and in vivo. This study demonstrates that the liver slice model is a simple and useful technique to investigate the underlying mechanisms of paracetamol-induced cell injury.  相似文献   

14.
The in vitro dissolution of ciprofloxacin from commercially available tablets and capsules in China was studied using the USP apparatus I to compare the product performance from nine different manufacturers. Cumulative release greater than 75% was obtained from all of the products tested within 45 min. However, statistically significant differences were found between some of the products when in vitro data were analyzed using the Weibull function, similarity factor (f2), and multivariate analysis of variances.  相似文献   

15.
We have investigated the relationship between ATP levels and the onset and progression of cell injury induced by paracetamol overdose both in vivo and in vitro. Liver slices obtained from phenobarbitone-induced and non-induced rats were used in a model in vitro system. Slices were exposed to paracetamol (2-10 mM), for 120 min and then incubated without paracetamol for a further 240 min. ATP levels are reduced upon exposure to paracetamol in liver slices from both phenobarbitone-induced and non-induced rats. Cell injury, as quantified by measuring leakage of lactate dehydrogenase (LDH) and potassium (K+), does not become apparent until 240 min, some 120 min after exposure to paracetamol had ended. This irreversible cell injury is not observed in liver slices from non-induced rats. For in vivo studies rats were phenobarbitone-induced and received i.p. injections of 800 mg/kg body weight paracetamol. Hepatic ATP levels were measured and are found to drop sharply by 3 h post-injection. Development of irreversible hepatic cell injury was assessed by measuring serum enzyme (ALT) activity. ALT levels do not rise until 12 h have elapsed. Paracetamol in overdose gives rise to ATP depletion in liver cells, that is early, independent of paracetamol metabolism and probably spread throughout the lobule. In contrast cell injury is found late and only in our phenobarbitone-induced rats. No cell injury is observed in liver slices from non-induced rats. This suggests that while the level of ATP depletion which is observed may be a necessary part of cell injury by paracetamol, it is not a sufficient cause.  相似文献   

16.
We studied the dissolution and absorption of ibuprofen (IB) from a three-layer tablet: the 1st layer (CIB layer) consisted of IB which was coated with anhydrous silicic acid (CIB), the 2nd layer was bromovalerylurea and anhydrous caffeine, and the 3rd layer was bromovalerylurea and ethenzamide. Differential scanning calorimetry and powder X-ray diffraction studies showed that the crystallinity of IB was not influenced by the preparation of CIB. The dissolution and absorption of IB from the CIB layer of the three-layer tablet were compared with those of a commercial tablet. In a test solution at pH 1.2, the dissolution rate of IB from the CIB layer was higher than that from the commercial tablet; moreover, the time for peak concentration (Tmax) after administration of the CIB layer was significantly shorter. The Tmax of the CIB layer tablet was about 52 min, while that of the commercial tablet was about 103 min. The rapid dissolution and absorption of IB in the CIB layer may be due to enhanced permeation, disintegration and disaggregation of CIB.  相似文献   

17.
The drug release of felodipine, a water-insoluble drug, was tested by using sodium lauryl sulphate (SLS), polyoxyethylene 20 sorbitan monooleate (Tween) or cetyltrimethylammonium bromide (CTAB) in the test medium as solubilizers. Three slightly different felodipine extended-release (ER) tablets 10 mg based on the gel matrix principle were evaluated under different solubilizer concentrations, agitation intensities and pH. These tablets were also tested in a bioavailability study together with an oral solution. All three solubilizers substantially enhanced the drug solubility and sink conditions were obtained. The choice of solubilizer affected the drug release rate. This is most probably due to physico-chemical interactions between the gel-forming agent and the solubilizers. All in vitro test conditions provided a good correlation (r2 = 0.94-0.97) to in vivo dissolution, as determined by moment analysis. However, a much steeper in vitro/in vivo relationship was obtained for SLS compared to Tween and CTAB reflecting an inferior discrimination between the tablets by use of this anionic solubilizer.  相似文献   

18.
The relationship between in vitro drug release characteristics from colon delivery systems and in vivo drug absorption was investigated using three kinds of delayed-release systems. 5-aminosalicylic acid (5-ASA), tegafur (FT) and carbamazepine (CBZ) were selected as model drugs. Pressure-controlled colon delivery capsules (PCC) for liquid preparations, time-controlled colon delivery capsules (TCC) for liquid and solid preparations and Eudragit S coated tablets for solid preparations were used in this study. At first, in vitro dissolution tests for all preparations were performed. Drug release from solid preparations was delayed compared to that from liquid preparations with all three drugs. Next, these preparations were administered to fasted beagle dogs. For 5-ASA, the mean Cmaxs (peak level) of Eudragit S coated tablets and PCC were 5.52 and 16.89 micrograms ml-1, respectively. The mean Tmaxs (time when drug reached peak level) were 3.0 and 5.3 h. AUCs were 22.57 and 48.09 micrograms.h ml-1, respectively. For FT, Cmaxs of Eudragit S coated tablet and PCC were 0.87 and 1.46 micrograms ml-1, and Tmaxs were 7.0 and 6.7 h, respectively. AUCs were 9.73 and 15.55 micrograms.h ml-1 and bioavailabilities were 43.79 and 70.84%. For CBZ, the mean Cmaxs of liquid preparations and solid preparations were 0.37 and 0.22 micrograms ml-1, respectively. The mean Tmaxs were 4.7 and 4.3 h. AUCs were 0.673 and 0.392 micrograms.h ml-1. With liquid preparations, drug was thought to contact to the colonic membrane easily because of lack of interference by stools, and to be absorbed well as compared with solid preparations. From these findings, drug release from colon delivery systems and drug dissolution in the colonic lumen are very important factors for the systemic availability of drugs from the colon delivery systems.  相似文献   

19.
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.  相似文献   

20.
In this study, in vitro characterization, bioavailability and pharmacokinetics of 2 different sustained-release diclofenac sodium dosage forms were compared, Voltaren (100 mg tablets), manufactured by Ciba-Geigy and Inflaban (100 mg enteric-coated tablets), manufactured by the Arab Pharmaceutical Manufacturing Company. The in vitro results demonstrated a faster rate of dissolution for Inflaban as compared to Voltaren, but both products exhibited a sustained-release pattern. The bioavailability study was conducted on 20 healthy male subjects who received a single oral dose (100 mg) of each product according to a randomized 2-way crossover design. Blood samples were obtained over a 26-hour period, and drug concentrations were determined by an HPLC method. Concentration time profiles revealed a sustained-release pattern for both products. The Tlag for Voltaren was 0.8 +/- 0.2 h, significantly shorter than for Inflaban (1.7 +/- 0.2 h) indicating a faster rate of absorption from the upper gastrointestinal tract. The Cmax obtained with Voltaren was significantly higher than that obtained with Inflaban (1,161 +/- 102 and 799 +/- 83, respectively). With respect to Tmax and AUC0-26h parameters, both products were not found to be statistically different. Tmax for Voltaren and Inflaban was 4.2 +/- 0.5 and 4.5 +/- 0.4 h, respectively, whereas AUC0-26h values for both products were 5,423 +/- 562 and 5,237 +/- 520 ng x h/ml, respectively. It is believed that the observed differences between Voltaren and Inflaban are mainly due to the fact that Inflaban is designed as an enteric-coated tablet form, with a core tablet having different sustained-release behavior. In addition, the effect of food on the bioavailability of Inflaban was evaluated in randomly selected 6 male volunteers. Our results revealed that, following light and heavy meals, the AUC0-30 and Cmax were minimally affected by food whereas a significant increase in Tmax and Tlag as compared to fasting conditions was observed.  相似文献   

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