Dissolution profiles of mesalazine formulationsin vitro

In vitro dissolution profiles of three controlled-release mesalazine formulations were determined at pH 1.0, 6.0 and 7.5. A closed-column type dissolution apparatus was used. A reproducible gradual dissolution profile was seen for Pentasa^® at all pH values. Dissolution starts immediately and is complete after 20 h. Dissolution profiles at pH 1 and pH 7.5 are much alike and dissolution is faster than at pH 6. The behaviour of Asacol^® at different pH values corresponds with the expectations: no release at pH 6 and pH 1, fast release at pH 7.5. Dissolution starts after 1 h and is complete after 3 h. Mesalazine release from Salofalk^® tablets at pH 7.5 and pH 6.0 starts after 2 and 3 h, respectively, and is complete after 5 and 10 h. However, after a long lag-time (10 h) mesalazine is also released from Salofalksu^® tablets at pH 1 and dissolution is complete after 23 h.     

Comparative bioavailability of josamycin,a macrolide antibiotic,from a tablet and solution and the influence of dissolution on in vivo release

The bioavailability of josamycin from a tablet formulation (2 × Josacine® 500 mg tablets) was investigated and compared with the bioavailability of a solution (containing 1 g drug and buffered at pH 4.0) following administration to six healthy human volunteers. Bioavailability profiles for the solution indicated that the drug was inherently rapidly absorbed with a mean C_max of 1.64±0.67 mg L⁻¹ attained at a mean t_max of 0.39±0.08 h. The AUC_0–last was 1.510±0.687 mg h L⁻¹. Bioavailability was significantly lower from the tablets than from the solution. Highly variable serum concentration–time profiles were obtained from the tablets and C_max values ranged from 0.05 to 0.71 mg L⁻¹ with a t_max range of 0.33–2.0 h. AUC_0–last values ranged from 0.03 to 0.95 mg h L⁻¹. Dissolution of josamycin from the tablets was generally unaffected at low pH (pH 1.2–5.0), but, rather, limited predominantly by tablet disintegration. However, dissolution was increasingly limited as the pH increased from 5.0 to 9.0. Besides poor disintegration, the particularly low intrinsic dissolution rate and solubility of josamycin at these pH values is likely to further reduce the dissolution rate. Comparison of the solution and tablet serum concentration–time profiles suggests that the absorption of josamycin from the tablets was dissolution rate limited. This is supported by the in vitro dissolution–pH topogram, which suggests that dissolution will be particularly rate limiting if dissolution of whole or parts of tablets occurs in gastro-intestinal fluid above pH 5.0. © 1998 John Wiley & Sons, Ltd.     

Plasma concentrations,bioavailability and dissolution of chlorpropamide

Summary The bioavailability of chlorpropamide from two new formulations (Melitase^® tablets) has been compared to that from a reference formulation which is currently in clinical use as a hypoglycaemic agent. In both rate and extent of bioavailability, all three formulations may be considered equivalent, providing allowances are made for differences in drug content. With 95% confidence, the mean bioavailability of chlorpropamide from the new formulations was within about 16% of the mean from the reference formulation, and formulation-related differences were not statistically significant. Although all three formulations were shown to have similar dissolution profiles, dissolution of chlorpropamide was pH-dependent in vitro. Dissolution was almost complete during 30 min at pH 7.2, but only 40%–60% had dissolved during 90 min at pH 2.0. A peak mean concentration of 22.7 µg/ml was reached 3 h after administration of 2×100 mg tablets of the new formulation and peak mean concentrations of 26.8 µg/ml and 27.4 µg/ml were reached 3 h and 4 hours after administration of one 250 mg tablet of the new formulation and one 250 mg tablet of the reference formulation respectively. Formulation-related differences of mean plasma concentrations (after scaling for equal doses of 250 mg) were not significant and each formulation provided similar plasma concentrations at corresponding times after administration. Statistically significant subject-related differences in all the parameters of bioavailability were shown by analyses of variance.     

Effects of liquisolid formulations on dissolution of naproxen

The aim of this study was to investigate the use of liquisolid technique in improving the dissolution profiles of naproxen in a solid dosage form. This study was designed to evaluate the effects of different formulation variables, i.e. type of non-volatile liquid vehicles and drug concentrations, on drug dissolution rates. The liquisolid tablets were formulated with three different liquid vehicles, namely Cremophor^® EL (polyoxyl 35 castor oil), Synperonic^® PE/L61 (poloxamer 181, polyoxyethylene-polyoxypropylene copolymer) and poly ethylene glycol 400 (PEG400) at two drug concentrations, 20%w/w and 40%w/w. Avicel^® PH102 was used as a carrier material, Cab-o-sil^® M-5 as a coating material and maize starch as a disintegrant. The empirical method as introduced by Spireas and Bolton (1999) [1] was applied strictly to calculate the amounts of coating and carrier materials required to prepare naproxen liquisolid tablets. Quality control tests, i.e. uniformity of tablet weight, uniformity of drug content, tablet hardness, friability test, disintegration and dissolution tests were performed to evaluate each batch of prepared tablets. In vitro drug dissolution profiles of the liquisolid formulations were studied and compared with conventional formulation, in simulated gastric fluid (pH 1.2) and simulated intestinal fluid (pH 7.2) without enzyme. Stability studies were carried out to evaluate the stability of the tablets under humid conditions. Differential scanning calorimetry and Fourier transform infrared were used to investigate physicochemical interaction between naproxen and the excipients. It was found that liquisolid tablets formulated with Cremophor^® EL at drug concentration of 20%w/w produced high dissolution profile with acceptable tablet properties. The stability studies showed that the dissolution profiles of liquisolid tablets prepared with Cremophor^® EL were not affected by ageing significantly. Furthermore, DSC revealed that drug particles in liquisolid formulations were completely solubilised.     

Gastrointestinal spread of oral prolonged-release mesalazine microgranules (Pentasa) dosed as either tablets or sachet

BACKGROUND: There is increasing interest in using higher dosages of mesalazine for the treatment of inflammatory bowel disease; however, with current mesalazine products this involves the use of 8-16 tablets per day. AIM: To evaluate the disposition, dispersion and movements of Pentasa prolonged-release microgranules following single dosing of either tablets (2 x 500 mg) or a new 1 g sachet (unit dose, microgranules in a foil bag). METHODS: A randomized crossover study in eight healthy volunteers was undertaken. Both formulations were radiolabelled by neutron activation and dosed in the fasted state. Location of the preparations in the bowel was assessed over 24 h by scintigraphy. RESULTS: Dissolution testing at pH 7.5 showed comparable in vitro mesalazine release properties for the tablet and sachet preparations. In vivo disposition of the microgranules administered as either tablets or sachet was comparable in terms of gastric emptying, small intestinal transit and colon arrival. CONCLUSIONS: Pentasa sachets 1 g unit dose offers the same release of mesalazine as Pentasa 500 mg tablets. Drug release occurs throughout the gastrointestinal tract from stomach to colon, with the advantage of fewer oral doses and ease of swallowing.     

In-vivo and In-vitro Correlation for Delayed-release Behaviour of a Molsidomine/O-carboxymethyl-O-ethyl-β-cyclodextrin Complex in Gastric Acidity-controlled Dogs

The in-vivo absorption behaviour of molsidomine from the delayed-release tablets of an O-carboxy-methyl-O-ethyl-β-cyclodextrin complex was investigated using gastric acidity-controlled dogs under fasted and non-fasted conditions. The in-vitro release profiles were generated by changing the pH of the dissolution medium at different rotation paddle speeds. The absorptivity of molsidomine in the high acidity dog was correlated with the pH-changed release profile (pH 1·2 to 7·0 after 2 h), whereas that in the low acidity dog was correlated with the release profile at a constant pH of 7·0. The absorption in fasted dogs was well correlated with the in-vitro release at the low-rotation paddle speed (< 5 rev min^?1), whereas that in the non-fasted dogs was correlated with that of high rotation (100 rev min^?1). The present results suggested that the in-vivo delayed-release behaviour of the complex is predictable from the in-vitro release profiles generated using pH-variable dissolution testing apparatus at different rotation speeds of the paddle.     

元胡止痛分散片中延胡索乙素的体外溶出度研究

目的：探讨元胡止痛分散片中延胡索乙素的体外溶出度及溶出动力学.方法：采用小杯法,考察不同pH的溶液中延胡索乙素的溶出情况,选择合适的溶出介质;以自制普通片为参比制剂,采用HPLC法测定2制剂的累积溶出度,并分别用零级动力学、一级动力学、Highchi方程、Weibull方程进行溶出动力学拟合.结果：分散片中延胡索乙素的溶出受pH影响较大,在pH值1的盐酸溶液中溶出快而完全;与普通片相比,分散片溶出速率快,其溶出过程可用一级动力学或Weibull分布模型较好地拟合.结论：元胡止痛分散片在pH值1介质中的体外溶出动力学符合一级动力学或Weibull分布模型,具有速释作用.     

Evaluation of Preflo® Modified Starches as New Direct Compression Excipients. I. Tabletting Characteristics

This investigation evaluated some new (Preflo^®) and existing commercially available (Starch 1500, Star Tab) modified starches as direct compression excipients. Preflo^® corn starches (CH-10, CH-20, CH-30) and Preflo^® potato starches (P-250, PI-10, PJ-20) were evaluated and compared with respect to their pharmaceutical properties such as particle size, density, flowability, friability, and compression properties. Preflo^® starches showed a high bulk density and good flowability. Preflo^® corn starches and Star Tab formed harder tablets than Preflo^® potato starches and Starch 1500. Data from the Athy-Heckel plots indicated that the Preflo^® starches are soft materials and, unlike Starch 1500, undergo plastic deformation. Tablets containing acetaminophen were also compressed with the starches and disintegration and dissolution studies were conducted. Starch 1500 tablets disintegrated in 3.5 min, whereas none of the Preflo^® starch tablets disintegrated in 30 min. While complete acetaminophen release occurred in 25 min from Starch 1500 tablets, the drug dissolution time from Preflo^® starch tablets varied from 4 to 12 hr, indicating a potential use for some of these starches in solid oral modified-release dosage forms.     

对柳氮磺吡啶肠溶片释放行为及其限度标准的探讨

目的：考察《中国药典》2010年版柳氮磺吡啶肠溶片中薄膜衣片和糖衣片处方工艺对释放度的影响,探讨其释放度限度标准的科学性与合理性。方法：采用转篮法（转速为100 r·min^-1）,考察国内7家生产企业样品在pH 6.0,pH 6.8,pH 7.5磷酸盐缓冲液中的体外释放行为。结果：在pH 7.5磷酸盐缓冲液中,不同企业的肠溶薄膜衣片释放曲线一致;薄膜衣片和糖衣片的释放曲线存在差异;在pH 6.0和pH 6.8磷酸盐缓冲液中,国内原研企业的薄膜衣片释放行为最符合该品种的药剂学特性。结论：通过对比国内外药典关于该品种的释放度限度规定及国内样品在3种释放介质中的释放行为研究,认为《中国药典》2010年版柳氮磺吡啶肠溶片释放度限度标准有待完善,肠溶糖衣片的处方工艺有待优化。     

Comparison between the dissolution profiles of nine meloxicam tablet brands commercially available in Buenos Aires,Argentina

In this work, the dissolution profiles of nine meloxicam tablet brands marketed in Argentina have been evaluated. As meloxicam is a Class 2 Biopharmaceutical Classification System (BSC) drug, interchangeability between commercial products must be demonstrated through in vivo bioequivalence studies. However, in our country, such studies remain to be performed.Dissolution studies have been performed according to USP 38 and evaluated by fitting experimental data to the zero and first-order, the Hixson-Crowell, the Higuchi, and the Weibull model-dependent methods. To test the pertinence of these release models, the Akaike Information Criteria (AIC) were used.All brands satisfied the dissolution profiles (phosphate buffer, pH 7.5) established in the USP. The comparison between the dissolution profiles was carried out by model-dependent and model-independent methods. The Weibull model provided the best kinetic curve adjustment. Brands I, II, IV and VI had the best fitting, with the maximum determination coefficient and the smallest AIC values. Model-independent methods included ratio test and the fit factors. The Dissolution Efficiency (DE) and Mean Dissolution Time (MDT) were analysed with ANOVA and the DGC method. In both cases, brand I did not show similarity with the rest of the brands. Using fit factors, only brands I, II and V were similar to each other.Significant differences were found among the in vitro dissolution profiles of meloxicam tablets belonging to the nine brands. As meloxicam is a class 2 BCS drug, interchangeability between commercial products must be demonstrated through in vivo bioequivalence studies. However, in Argentina, such studies remain to be performed. Our results demonstrate that caution must be exercised as regards interchangeability of generic products.     

Assessment of the pharmaceutical quality of marketed enteric coated pantoprazole sodium sesquihydrate products

Pantoprazole sodium sesquihydrate (PSS) is a proton pump inhibitor, used in acid-related disorders, like peptic ulcer and gastroesophageal reflux. Increasing the number of pantoprazole containing products in the market, raises questions of its efficacy and generic substitution. The pharmaceutical quality of 6 generic PSS enteric coated tablets in 2 local markets was assessed relative to the innovator product (pantozol®). Uniformity of dosage unit, disintegration and in vitro drug release were determined using United States pharmacopeia for delayed release tablets. The similarity factor (f2) was assessed using the FDA recommended approach (f2 similarity factor). The content uniformity of the innovator product was 98.39% of the labeled claim with RSD value of 1.08%, while the content of generic products ranged from 96.98% to 98.80% with RSD values of 1.24–2.19%. All the products showed no disintegration, cracks or swelling in 0.1 N HCl, except product 1, which showed complete disintegration after 20 min. However, the disintegration of all the products in phosphate buffer met USP requirements. Dissolution of tablets in 0.1 N HCl showed no drug release after 2 h except product 1 in which one tablet showed a drug release more than 10% at acid stage level A1. In addition, three tablets of this product showed dissolution of 45%, 48% and 69% at acid stage level A2. The similarity factor f2 of the products was between 71 and 74 indicating the similarity in dissolution profiles of all the products in accordance to FDA requirements, except product 1 in which f2 value was 18.67.     

Mucoadhesive platforms for targeted delivery to the colon

A novel platform system, comprising a mucoadhesive core and a rapid release carrier, was designed for targeted drug delivery to the colon. Prednisolone pellets containing different carbomers, including Carbopol 971P, Carbopol 974P and Polycarbophil AA-1, with or without organic acids, were produced by extrusion-spheronization. Mucoadhesive pellets were coated with a new enteric double-coating system, which dissolves at pH 7. This system comprises an inner layer of partially neutralized Eudragit^® S and buffer salt and an outer coating of standard Eudragit^® S. A single layer of standard Eudragit S was also applied for comparison purposes. Dissolution of the coated pellets was assessed in USP II apparatus in 0.1 N HCl followed by Krebs bicarbonate buffer pH 7.4. Visualization of the coating dissolution process was performed by confocal laser scanning microscopy using fluorescent markers in both layers. The mucoadhesive properties of uncoated, single-coated and-double coated pellets were evaluated ex vivo on porcine colonic mucosa. Mucoadhesive pellets coated with a single layer of Eudragit^® S release its cargo after a lag time of 120 min in Krebs buffer. In contrast, drug release from the double-coated mucoadhesive pellets was significantly accelerated, starting at 75 min. In addition, the mucoadhesive properties of the core of the double coated pellets were higher than those from single-coated pellets after the core had been exposed to the buffer medium. This novel platform technology has the potential to target the colon and overcome the variability in transit and harmonize drug release and bioavailability.     

Dynamic Dissolution Testing To Establish <Emphasis Type="BoldItalic">In Vitro</Emphasis>/<Emphasis Type="BoldItalic">In Vivo</Emphasis> Correlations for Montelukast Sodium,a Poorly Soluble Drug

Purpose  The objectives of the study was to develop a dissolution test method that can be used to predict the oral absorption of montelukast sodium, and to establish an in vitro/in vivo correlation (IVIVC) using computer simulations. Methods  Drug solubility was measured in different media. The dissolution behaviour of montelukast sodium 10 mg film coated tablets was studied using the flow-through cell dissolution method following a dynamic pH change protocol, as well as in the USP Apparatus 2. Computer simulations were performed using GastroPlus™. Biorelevant dissolution media (BDM) prepared using bile salts and lecithin in buffers was used as the dissolution media, as well as the USP simulated intestinal fluid (SIF) pH 6.8 and blank FaSSIF pH 6.5. Dissolution tests in the USP Apparatus 2 were performed under a constant pH condition, while the pH range used in the flow through cells was pH 2.0 to 7.5. The in vitro data were used as input functions into GastroPlus™ to simulate the in vivo profiles of the drug. Results  The solubility of montelukast sodium was low at low pH, but increased as the pH was increased. There was no significant difference in solubility in the pH range of 5.0 to 7.5 in blank buffers, but the drug solubility was higher in biorelevant media compared with the corresponding blank buffers at the same pH. Using the flow through cells, the dissolution rate was fast in simulated gastric fluid containing 0.1% SLS. The dissolution rate slowed down when the medium was changed to FaSSIF pH 6.5 and increased when the medium was changed to FaSSIF medium at pH 7.5. In the USP Apparatus 2, better dissolution was observed in FaSSIF compared with the USP buffers and blank FaSSIF with similar pH values. Dissolution was incomplete with less than 10% of the drug dissolved in the USP-SIF, and was practically non existent in blank FaSSIF pH 6.5. The in vitro results of the dynamic dissolution test were able to predict the clinical data from a bioavailability study best. Conclusions  Dynamic dissolution testing using the flow through cell seems to be a powerful tool to establish in vitro/in vivo correlations for poorly soluble drugs as input function into GastroPlus.     

盐酸普萘洛尔脉冲释放片的制备及其体外释药研究

目的 制备盐酸普萘洛尔双层包衣脉冲释放片,并研究其体外释药行为。方法 采用粉末直接压片法制备盐酸普萘洛尔片芯,滚转包衣锅法分别包羟丙甲纤维素溶胀层和丙烯酸树脂控释层。采用体外溶出试验考察处方及溶出条件对本品释药行为的影响。结果 本品经过一定时滞后以脉冲形式释药,渗透活性物质氯化钠、溶胀层及控释层厚度、丙烯酸树脂RS/RL的配比均影响本品时滞。溶出方法及不同pH溶出介质对本产品的时滞无影响。结论 盐酸普萘洛尔脉冲释放片具有脉冲释放特性,体外时滞约为4 h。     

Formulation of 3D Printed Tablet for Rapid Drug Release by Fused Deposition Modeling: Screening Polymers for Drug Release,Drug-Polymer Miscibility and Printability

The primary aim of this study was to identify pharmaceutically acceptable amorphous polymers for producing 3D printed tablets of a model drug, haloperidol, for rapid release by fused deposition modeling. Filaments for 3D printing were prepared by hot melt extrusion at 150°C with 10% and 20% w/w of haloperidol using Kollidon^® VA64, Kollicoat^® IR, Affinsiol^?15 cP, and HPMCAS either individually or as binary blends (Kollidon^® VA64 + Affinisol^? 15 cP, 1:1; Kollidon^® VA64 + HPMCAS, 1:1). Dissolution of crushed extrudates was studied at pH 2 and 6.8, and formulations demonstrating rapid dissolution rates were then analyzed for drug-polymer, polymer-polymer and drug-polymer-polymer miscibility by film casting. Polymer-polymer (1:1) and drug-polymer-polymer (1:5:5 and 2:5:5) mixtures were found to be miscible. Tablets with 100% and 60% infill were printed using MakerBot printer at 210°C, and dissolution tests of tablets were conducted at pH 2 and 6.8. Extruded filaments of Kollidon^® VA64-Affinisol^? 15 cP mixtures were flexible and had optimum mechanical strength for 3D printing. Tablets containing 10% drug with 60% and 100% infill showed complete drug release at pH 2 in 45 and 120 min, respectively. Relatively high dissolution rates were also observed at pH 6.8. The 1:1-mixture of Kollidon^® VA64 and Affinisol^?15 cP was thus identified as a suitable polymer system for 3D printing and rapid drug release.     

Dissolution of Commercially Available Mesalamine Formulations at Various pH Levels

Introduction

Mesalamine (5-aminosalicylic acid; 5-ASA) is recommended first-line therapy for mild-to-moderate ulcerative colitis. Many mesalamine formulations employ a pH-dependent release mechanism designed to maximize drug release in the colon. This study compared the in vitro release of 5-ASA from six commercially available mesalamine formulations at pH levels similar to those typically encountered in the human gastrointestinal tract.

Methods

The release of 5-ASA from six mesalamine formulations [Mesalazin-Kohlpharma (Kohlpharma, Germany), Mesalazin-Eurim (Eurimpharm, Germany), Mesalazina-Faes (Faes Farma, Spain), Mesalazine EC (Actavis B.V., Netherlands), Mesalazine EC 500 PCH (Pharmachemie B.V., Netherlands); multimatrix mesalamine (Shire US Inc., USA)] was monitored separately at three different pH levels [1.0 (2 h), 6.4 (1 h), and 7.2 (8 h)] using United States Pharmacopeia dissolution apparatus II. The dissolution percentage was calculated as a mean of 12 units for each formulation.

Results

At pH 1.0 and 6.4, <1 % of 5-ASA release was observed for each of the mesalamine formulations tested. At pH 7.2, complete release of 5-ASA occurred within 1 h for Mesalazine EC and Mesalazine EC 500 PCH, and within 2 h for Mesalazin-Kohlpharma, Mesalazin-Eurim, and Mesalazina-Faes; complete release of 5-ASA from multimatrix mesalamine occurred within 7 h. Little variability in rate of 5-ASA dissolution was observed between tablets of each formulation.

Conclusion

At pH 7.2, 5-ASA release profiles were variable among the commercially available mesalamine formulations that were tested.     

Evolution of a physiological pH 6.8 bicarbonate buffer system: Application to the dissolution testing of enteric coated products

The use of compendial pH 6.8 phosphate buffer to assess dissolution of enteric coated products gives rise to poor in vitro-in vivo correlations because of the inadequacy of the buffer to resemble small intestinal fluids. A more representative and physiological medium, pH 6.8 bicarbonate buffer, was developed to evaluate the dissolution behaviour of enteric coatings. The bicarbonate system was evolved from pH 7.4 Hanks balanced salt solution to produce a pH 6.8 bicarbonate buffer (modified Hanks buffer, mHanks), which resembles the ionic composition and buffer capacity of intestinal milieu. Prednisolone tablets were coated with a range of enteric polymers: hypromellose phthalate (HP-50 and HP-55), cellulose acetate phthalate (CAP), hypromellose acetate succinate (HPMCAS-LF and HPMCAS-MF), methacrylic acid copolymers (EUDRAGIT® L100-55, EUDRAGIT® L30D-55 and EUDRAGIT® L100) and polyvinyl acetate phthalate (PVAP). Dissolution of coated tablets was carried out using USP-II apparatus in 0.1 M HCl for 2 h followed by pH 6.8 phosphate buffer or pH 6.8 mHanks bicarbonate buffer. In pH 6.8 phosphate buffer, the various enteric polymer coated products displayed rapid and comparable dissolution profiles. In pH 6.8 mHanks buffer, drug release was delayed and marked differences were observed between the various coated tablets, which is comparable to the delayed disintegration times reported in the literature for enteric coated products in the human small intestine. In summary, the use of pH 6.8 physiological bicarbonate buffer (mHanks) provides more realistic and discriminative in vitro release assessment of enteric coated formulations compared to compendial phosphate buffer.     

Pharmacokinetic modelling of microencapsulated metronidazole

The aim of present study is to develop a pharmacokinetic model for microencapsulated metronidazole to predict drug absorption pattern in healthy human and validate this model internally.  Metronidazole was microencapsulated into ethylcellulose shells followed by the conversion of these microcapsules into tablets.  Dissolution study of tablets was conducted in 450 mL double distilled water, 0.1 mol·L⁻¹ HCl and phosphate buffer (pH 6.8) maintained at (37 ± 0.5) ℃ using USP apparatus II at 50, 100 and 150 r·min⁻¹.  Three metronidazole tablets (T₁: fast release, T₂: moderate release, T₃: slow release and reference) were administered to twenty four healthy human volunteers and serial blood samples were collected for 12 hours followed by their analysis using RP-HPLC.  Drug release data were analyzed by various model dependent and independent approaches.  Drug absorbed (%) was determined by Wagner-Nelson method from plasma concentration profile.  Internal predictability was checked from C_max and AUC.  Optimum dissolution profile was observed in double distilled water and 50 r·min⁻¹.  A good level A correlation was observed between drug dissolution and absorption profiles (correlation coefficient, R² = 0.900 9, 0.942 6, 0.901 5 and 0.932 for T₁, T₂, T₃ and reference, respectively).  Internal    predictability was found less than 10%.  Good correlation coefficients and low prediction errors elaborate the validity of this mathematical in-vitro in-vivo correlation model as a predictive tool for the determination of  pharmacokinetics from dissolution data.     

Effect of binders on the release rates of direct molded verapamil tablets using twin-screw extruder in melt granulation

Conventional manufacturing of pharmaceutical tablets often involves single processes such as blending, granulation, milling and direct compression. A process that minimizes and incorporates all these in a single continuous step is desirable. The concept of omitting milling step followed by direct-molding of tablets utilizing a twin-screw extruder in a melt granulation process using thermoplastic binders was explored. The objective of this study was to investigate the effect of combining hydrophilic binder (HPMC K4M, PEO 1M), and hydrophobic binder (Compritol^® ATO 888, Precirol^® ATO 5) on the release profiles of direct-molded tablets and direct-compressed tablets from milled extrudates using a quality-by-design approach. It was identified that hydrophilic binder type and process significantly affects (p = 0.005) the release profiles of verapamil. Moreover, two-way interaction analysis demonstrated that the combination of process with type of hydrophilic polymer (p = 0.028) and the type of hydrophilic polymer with polymer ratio (p = 0.033) significantly affected the release profiles. The formulation release kinetics correlated to Higuchi release model and the mechanism correlated to a non-Fickian release mechanism. The results of the present study indicated that direct-molded tablets with different release profiles can be manufactured without milling process and through a continuous melt granulation using twin-screw extruder with appropriate thermoplastic binder ratio.     

多条实时溶出曲线对阿昔洛韦片的质量再评价

目的:以多条实时溶出曲线评价阿昔洛韦片的内在质量。方法:分别以pH1.0的盐酸溶液、pH4.0的醋酸盐缓冲液、pH6.8的磷酸盐缓冲液和水为溶出介质,设定检测波长254 nm、参比波长550 nm、转速50 r.min-1、光程0.5 mm和桨法,用光纤溶出度实时测定仪测定阿昔洛韦片的溶出曲线。结果:测定了9个厂家生产的阿昔洛韦片在4种溶出介质中的实时溶出曲线,结果显示3个厂家生产的阿昔洛韦片的4条溶出曲线不一致,反映出3个厂家的生产工艺尚不成熟。结论:不同pH溶出介质中的实时溶出曲线可全面反映药物在不同体内环境下的溶出行为,能更有效地评价制剂的内在质量。