Release Kinetics and Availability of Mebeverine Hydrochloride from Polycarbophil Loaded by Swelling

The release rate and mechanism of release of mebeverine hydrochloride were studied for commercial “Duspatalin” tablets and for different tablet formulations (F₁, F₂ & F₃) containing 20, 40 and 65% polycarbophil, respectively. The formulated granules were obtained by freeze drying of polycarbophil granules loaded with aqueous solution of the drug at 25°C by swelling of the polymer. The release of mebeverine hydrochloride from prepared tablet formulations was faster than that of Duspatalin tablets. The release rate of the drug increased as the polycarbophil content of the tablets increased. The calculated correlation coefficients for the release data fitted to various models showed that the release from Duspatalin tablets and F₂ follow first order kinetics, while release of F₁ approaches that of zero order. The release mechanism from F₃ could not be determined. DSC thermograms showed that there is an interaction between the drug and the polymer in aqueous medium, but not in the solid state.

The in-vivo guinea-pig studies revealed that mebeverine hydrochloride was released and absorbed from the tested formula (F₃), depressed the agonists-induced contractions 2 hrs after treatment but not after 4 hrs indicating rapid absorption and metabolism. The percentage inhibitions ranged from 40–85%. The treatment seems to antagonise barium chloride (BaCl₂)-induced contractions more than those induced by carbochol.     

Development and evaluation of buccoadhesive tablet for selegiline hydrochloride based on thiolated polycarbophil

Selegiline hydrochloride (SHCl), a monoamine oxidase B inhibitor, is used as an adjunct in the therapy of Parkinson’s disease. This study is concerned with the preparation and evaluation of mucoadhesive buccal tablet for controlled systemic delivery of SHCl. Buccal absorption of selegiline can bypass its first-pass metabolism and improve bioavailability accompanied by greatly reduced metabolite formation, which is potentially of enhanced therapeutic value in patients with Parkinson’s disease. Polycarbophil–cysteine (PCP–cys) conjugate, which is a thiolated derivative of the mucoadhesive polymer polycarbophil, was synthesized by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride-mediated amide bond coupling. Tablets of SHCl based on native and thiolated polycarbophil were prepared. The prepared tablets were evaluated for drug content, swelling behavior, mucoadhesive strength, in vitro drug release, ex vivo permeation and in vitro cytotoxicity. PCP–cys tablets showed enhanced mucoadhesion and retarded drug release compared to polycarbophil tablets. Permeation data of SHCl from matrices prepared using the PCP–cys polymer revealed a significantly higher value of apparent permeability in comparison to polycarbophil, which supported the information in literature that thiolation imparts permeation enhancing properties to mucoadhesive polymers. In vitro cytotoxicity studies on PCP–cys using L-929 mouse fibroblast cell line indicated that conjugation with cysteine does not impart any apparent toxicity to polycarbophil. The results from the study indicate that the buccal delivery of SHCl using thiolated polycarbophil tablet could provide a way for improved therapy of Parkinson’s disease.     

Optimization and evaluation of time-dependent tablets comprising an immediate and sustained release profile using artificial neural network

The aim of this work was to optimize time-dependent tablets using artificial neural network (ANN). The time-dependent tablet consisted of a tablet core, which contained sustained release pellets (70% isosorbide-5-mononitrate [5-ISMN]), immediate release granules (30% 5-ISMN), superdisintegrating agent (sodium carboxymethylstarch, CMS-Na), and other excipients, surrounded by a coating layer composed of a water-insoluble ethylcellulose and a water-soluble channeling agent. The chosen independent variables, i.e., X₁ coating level of tablets, X₂ coating level of pellets, and X₃ CMS-Na level, were optimized with a three-factor, three-level Box-Behnken design. Data were analyzed for modeling and optimizing the release profile using ANN. Response surface plots were used to relate the dependent and the independent variables. The optimized values for the factors X₁-X₃ were 4.1, 14.1, and 29.8%, respectively. Optimized formulations were prepared according to the factor combinations dictated by ANN. In each case, the observed drug release data of the optimized formulations were close to the predicted release pattern. An in vitro model for predicting the effect of food on release behavior of optimized products was used in this study. It was concluded that neural network technique could be particularly suitable in the pharmaceutical technology of time-dependent dosage forms where systems were complex and nonlinear relationships often existed between the independent and the dependent variables.     

In-vitro evaluation of sustained-release dyphylline tablets

Dyphylline tablets were prepared by direct compression of mixtures of the drug, emcompress and different ratios of hydroxypropyl methylcellulose (HPMC) or cellulose acetate phthalate (CAP). Physical properties of the prepared tablets and the drug release in 0.1 N HC1 and phosphate buffer, pH 7.4 were investigated.

All tablets were found to satisfy the USP requirements regarding content, weight uniformity and friability. Hardness was greatly enhanced and thickness was slightly increased by increasing the polymer ratio in tablet formulations. Disintegration time of the dyphylline tablets was delayed by the presence of either HPMC or CAP and there was a direct relationship between the polymer ratio and the disintegration time. Considerable retardation in the rate and extent of drug release from the prepared tablets in both dissolution liquids was observed. As the polymer ratio increased in the tablet formulations, the drug release was significantly inhibited.     

Influence of granulating method on physical and mechanical properties, compression behavior, and compactibility of lactose and microcrystalline cellulose granules

The physical and mechanical properties of lactose (LC) and microcrystalline cellulose (MCC) granules prepared by various granulating methods were determined, and their effects on the compression and strength of the tablets were examined. From the force-displacement curve obtained in a crushing test on a single granule, all LC granules appeared brittle, and MCC granules were somewhat plastically deformable. Intergranular porosity ε_inter clearly decreased with greater spherical granule shape for both materials. Decrease in intragranular porosity ε_intra enhanced the crushing force of a single granule F_g. Agitating granulation brought about the most compactness and hardness of granules. In granule compression tests, the initial slope of Heckel plots K₁ appeared closely related to ease of filling voids in a granule bed by the slippage or rolling of granules. The reciprocal of the slope in the succeeding step 1/K₂ in compression of MCC granules indicated positive correlation to F_g, while in LC granules, no such obvious relation was evident. 1/K₂ differed only slightly among granulating methods. Tensile strength of tablets T_t obtained by compression of various LC granules was low as a whole and was little influenced by granulating method. For MCC granules, which are plastically deformable, tablet strength greatly depended on granulation. Granules prepared by extruding or dry granulation gave strong tablets. Tablets prepared from granules made by the agitating method showed particularly low T_t. From stereomicroscopic observation, the contact area between granule particles in a tablet appeared smaller; this would explain the decrease in intergranular bond formation.     

Studies on Drug Release from a Carbomer Tablet Matrix

The purpose of this investigation was to study the drug release mechanisms for tablet matrices of carbomer. Carbomer is a polymer of acrylic acid which is cross-linked with polyalkenyl polyether. The drug and the carbomer were blended and directly compressed into tablets using a laboratory Carver press. The influence of the level of carbomer, the type of drug, and the pH of dissolution media were investigated by measuring drug release kinetics. In general, the release of a relatively neutral molecule (e.g. theophylline) in the pH 7.2 phosphate buffer solution appears to exhibit nearly zero-order kinetics via a diffusion-controlled mechanism for all polymer levels studied (10-85%).

The drug release process based on diffusion can be described by the general expression:

M_t = k₁t^1/2 + k₂t

where M, represents the amount of the drug released at time t, and k₁, k₂ are related to kinetic constants characteristic of the drug delivery systems. The release kinetics are modified when an ionic species, such as sodium salicylate, is incorporated into the tablet matrix.     

Comparative Evaluations of Aqueous Film Coated Tablet Formulations by High Humidity Aging

Compressed tablets of ticlopidine hydrochloride were coated with three aqueous film coating formulations and aged under 95% relative humidity at 23° and 37°. The in vitro dissolution of the drug from tablets coated with the formulation containing polymethacrylic acid esters before aging was slower than the tablets coated with the formulations containing hydroxypropyl methylcellulose or ethylcellulose dispersion. On aging, the in vitro drug dissolution of the coated and uncoated tablets decreased and the decrease depended on the film forming excipient in the coating formulation and the temperature of aging. The tablets coated with the formulation containing polymethacrylic acid esters dissolved very slowly after aging. Higher moisture contents of the tablets after aging under 95% relative humidity at 23° compared to 37° resulted in a consistently lower tablet crushing strength. The tablets coated with the formulation containing 10% hydroxypropy1 methylcellulose showed a smaller decrease in the tablet crushing strength on aging compared to the other two formulations.     

Development of polysaccharide-based colon targeted drug delivery systems for the treatment of amoebiasis

The main focus of this study is to develop colon targeted drug delivery systems for metronidazole (MTZ). Tablets were prepared using various polysaccharides or indigenously developed graft copolymer of methacrylic acid with guar gum (GG) as a carrier. Various polysaccharides such as GG, xanthan gum, pectin, carrageenan, β-cyclodextrin (CD) or methacrylic acid-g-guar (MAA-g-GG) gum have been selected and evaluated. The prepared tablets were tested in vitro for their suitability as colon-specific drug delivery systems. To further improve the colon specificity, some selected tablet formulations were enteric coated with Eudragit-L 100 to give protection in an acidic environment. Drug release studies were performed in simulated gastric fluid (SGF) for 2 hr followed by simulated intestinal fluid (SIF) at pH 7.4. The dissolution data demonstrate that the rate of drug release is dependent upon the nature and concentration of polysaccharide/polymer used in the formulations. Uncoated tablets containing xanthan gum or mixture of xanthan gum with graft copolymer showed 30-40% drug release during the initial 4-5 hr, whereas for tablets containing GG with the graft copolymer, it was 70%. After enteric coating, the release was drastically reduced to 18-24%. The other polysaccharides were unable to protect drug release under similar conditions. Preparations with xanthan gum as a matrix showed the time-dependent release behavior. Further, in vitro release was performed in the dissolution media with rat caecal contents. Results indicated an enhanced release when compared to formulations studied in dissolution media without rat caecal contents, because of microbial degradation or polymer solubilization. The nature of drug transport was found to be non-Fickian in case of uncoated formulations, whereas for the coated formulations, it was found to be super-Case-II. Statistical analyses of release data indicated that MTZ release is significantly affected by the nature of the polysaccharide used and enteric coating of the tablet. Differential scanning calorimetry indicated the presence of crystalline nature of drug in the formulations.     

Spectrophdtometric Determination of Hydralazine Hydrochloride, Oxprenolol Hydrochloride & Chlorthalidone in Combination and for Oxprenolol Hydrochloride as Single Component Dosage Form

Three component tablet assay and single component tablet assay are presented. The first is performed for hydralazine hydrochloride, oxprenolol hydrochloride & chlorthalidone existing in a ratio 2.5: 8: 1 respectively. Hydralazine is estimated through absorbance measurements at 314 nm, D₁ at 315 nm or D₂-at 316 nm. Modified Vierordts method-after absorbance correction from hydralazine hydrochloride interference and also D₂ methods are applied for oxprenolol hydrochloride assay. Chlorthalidone, the minor component, is assayed after its extraction using D₁ or D₂ measured at 282 nm & 268-284 nm respectively. For single tablet assay, oxprenolol hydrochloride is assayed using A_max at 272 nm, D₁-measurement at 252-274 nm & D₂-measurement at 260-278 nm. The first method is suffering from systematic error corrected by the latter two methods.     

Application of similarity factor in development of controlled-release diltiazem tablet

Controlled-release grade hydroxypropylmethylcellulose (HPMC) or xanthan gum (XG) and microcrystalline cellulose (MCC) were employed to prepare controlled-release diltiazem hydrochloride tablets. The similarity factor f₂ was used for dissolution profile comparison using Herbesser 90 SR as a reference product. Drug release could be sustained in a predictable manner by modifying the content of HPMC or XG. Moreover, the drug release profiles of tablets prepared using these matrix materials were not affected by pH and agitation rate. The f₂ values showed that only one batch of tablets (of diltiazem HCl, HPMC or XG, and MCC in proportions of 3.0:3.0:4.0) was considered similar to that of the reference product, with values above 50. The unbiased similarity factor f^*₂ values were not much different from the f₂ values, ascribing to a small dissolution variance of the test and reference products. The amount of HPMC or XG incorporated to produce tablets with the desired dissolution profile could be determined from the curves of f₂ versus polymer content. Hence, the f₂ values can be applied as screening and optimization tools during development of controlled-release preparations.     

Strategies to overcome pH-dependent solubility of weakly basic drugs by using different types of alginates

Weakly basic drugs demonstrate higher solubility at lower pH, thus often leading to faster drug release at lower pH. The objective of this study was to achieve pH-independent release of weakly basic drugs from extended release formulations based on the naturally occurring polymer sodium alginate. Three approaches to overcome the pH-dependent solubility of the weakly basic model drug verapamil hydrochloride were investigated. First, matrix tablets were prepared by direct compression of drug substance with different types of sodium alginate only. Second, pH-modifiers were added to the drug/alginate matrix systems. Third, press-coated tablets consisting of an inner pH-modifier tablet core and an outer drug/sodium alginate coat were prepared. pH-Independent drug release was achieved from matrix tablets consisting of selected alginates and drug substance only. Alginates are better soluble at higher pH. Therefore, they are able to compensate the poor solubility of weakly basic drugs at higher pH as the matrix of the tablets dissolves faster. This approach was successful when using alginates that demonstrated fast hydration and erosion at higher pH. The approach failed for alginates with less-pronounced erosion at higher pH. The addition of fumaric acid to drug/alginate-based matrix systems decreased the microenvironmental pH within the tablets thus increasing the solubility of the weakly basic drug at higher pH. Therefore, pH-independent drug release was achieved irrespective of the type of alginate used. Drug release from press-coated tablets did not provide any further advantages as compound release remained pH-dependent.     

Evaluation of Stereoselective Dissolution of Racemic Salbutamol Matrices Prepared with Commonly Used Excipients and 1H-NMR Study

The purpose of this work was to examine the in vitro enantioselective dissolution of salbutamol from matrix tablets containing various chiral excipients, such as γ-cyclodextrin (γ-CD), heptakis (2,6-di-O-methyl)-β-cyclodextrin (DM-β-CD), sulfobutyl-β-cyclodextrin (SBE-β-CD), hydroxypropylmethylcellulose (HPMC), and egg albumin. In this study, two types of tablets were prepared; the coated tablet contained the complex of racemic salbutamol and cyclodextrin (γ-CD, DM-β-CD, and SBE-β-CD), and the uncoated tablet was composed of the drug with either HPMC or egg albumin. Subsequently, these formulations were evaluated for enantioselective release. The results revealed that the formulations containing either SBE-β-CD, HPMC, or egg albumin had no enantioselective release, while the formulation with DM-β-CD gave slightly different release of the two enantiomers at the end of the dissolution profile. The formulation containing γ-CD provided significant stereoselectivity throughout the dissolution profile. The release of the eutomer R-salbutamol was higher than that of the distomer S-salbutamol from the γ-CD tablet. In addition, the enantioselective interaction for the γ-CD inclusion complex was investigated by ¹H-NMR (nuclear magnetic resonance) spectroscopy and gave evidence to support the enantioselectivity obtained on dissolution.     

Application of Poly(oxyethylene) Homopolymers in Sustained Release Solid Formulations

Water soluble poly(oxyethylene) homopolymers, with molecular mass ranging from four hundred thousand to four million, were used as carriers to generate, by direct compression techniques, sustained release matrix tablets of both water-soluble and insoluble bioactive agents. Dissolution studies showed that the release kinetics of the tablets depends upon the solubility and molecular mass of polymer, solubility of drug, and the ratio of the drug to polymer in the tablets. Following drug release, the tablet components dissolved leaving behind no residue, or “ghost”, as is commonly observed with wax-based systems.     

Influence of hydroxypropyl methylcellulose mixture,apparent viscosity,and tablet hardness on drug release using a 2(3) full factorial design

This study investigates the effects of three factors: (1) use of a mixture of two different grades of hydroxypropyl methylcellulose (HPMC), (2) apparent viscosity, and (3) tablet hardness on drug release profiles of extended-release matrix tablets. The lot-to-lot apparent viscosity difference of HPMC K15M on in vitro dissolution was also investigated. Four test formulations were made, each containing 10% of a very water-soluble active pharmaceutical ingredient (API), 32% HPMC K15M, or a mixture of HPMC K100LV and HPMC K100M, 56% diluents, and 2% lubricants. Each formulation was made at two hardness levels. A 2³ full factorial design was used to study various combinations of the three factors using eight experiments conducted in a randomized order. Dissolution studies were performed in USP apparatus I. The values of t_50% (time in which 50% drug is released) and t_lag (lag time, the time taken by the matrix tablet edges to get hydrated and achieve a state of quasi-equilibrium before erosion and the advance of solvent front through the matrix occur) were calculated from each dissolution profile. The similarity factor (f₂) was also calculated for each dissolution profile against the target dissolution profile. A simple Higuchi-type equation was used to analyze the drug release profiles. Statistical analysis using analysis of variance (ANOVA) and similarity factor (f₂) values calculated from the data indicated no significant difference among the t_50% values and dissolution profiles respectively for all formulations. Within the 3.3-6 kp hardness range investigated, dissolution rates were found to be independent of tablet hardness for all the formulations. Although significantly shorter lag times were observed for the tablets formulated with low- and high-viscosity HPMC mixtures in comparison to those containing a single grade of HPMC, this change had no significant impact on the overall dissolution profiles indicated by the similarity factor f₂ values. From this study it can be concluded that lot-to-lot variability in apparent viscosity of HPMC should not be a concern in achieving similar dissolution profiles. Also, results indicated that within the viscosity range studied (12,000-19,500 cps) an HPMC mixture of two viscosity grades can be substituted for another HPMC grade if the apparent viscosity is comparable. Also, the drug release is diffusion-controlled and depends mostly on the viscosity of the gel layer formed.     

Comparative Evaluations of Aqueous Film Coated Tablet Formulations by High Humidity Aging

Compressed tablets of ticlopidine hydrochloride were coated with three aqueous film coating formulations and aged under 95% relative humidity at 23° and 37°. The in vitro dissolution of the drug from tablets coated with the formulation containing polymethacrylic acid esters before aging was slower than the tablets coated with the formulations containing hydroxypropyl methylcellulose or ethylcellulose dispersion. On aging, the in vitro drug dissolution of the coated and uncoated tablets decreased and the decrease depended on the film forming excipient in the coating formulation and the temperature of aging. The tablets coated with the formulation containing polymethacrylic acid esters dissolved very slowly after aging. Higher moisture contents of the tablets after aging under 95% relative humidity at 23° compared to 37° resulted in a consistently lower tablet crushing strength. The tablets coated with the formulation containing 10% hydroxypropy1 methylcellulose showed a smaller decrease in the tablet crushing strength on aging compared to the other two formulations.     

Effect of Particle Size on Deformation and Compaction Characteristics of Ascorbic acid and Potassium Chloride: Neat and Granulated Drug

Deformation and compaction characteristics of two soluble drugs, ascorbic acid and potassium chloride, were investigated. Five different particle size fractions of ascorbic acid with mean particle size (d₅₀) ranging from 30-300μm and four different particle size fractions of potassium chloride with d₅₀ ranging from 20-400 μm were selected in the study. The compaction behavior of the drug substances as neat drugs or as granulated drugs were evaluated on both a Carver press and an instrumented single-punch tablet press. The results clearly show that mean particle size of the drug substances plays an important role in their compactibility. Intrinsic compactibility of both drug substances was slightly improved with increased particle size. Granulations of the drugs with polyvinyl pyrrolidone significantly improved their compactibility. However, this effect was more pronounced in the drug substance with finer particle size. The Heckel plots indicate that deformation characteristics of both granulated drugs were related to their original mean particle sizes. The granulations prepared from the coarser particle size (d₅₀ 250 μm to 400 μm) underwent two stages of deformation, so-called “brittle fracture” and “plastic deformation”. While the granulations prepared from the finer particle size predoninantly underwent “plastic deformation”. The results indicated that the plastic deformation of both granulated drugs was progressively enhanced whilst fragmentation of particles was correspondingly reduced as the particle size of the drugs was decreased. Scanning electron photomicrographs indicated that the granulation process changed the surface morphology of the drug particles imparting more “microirregularities” or “defects”, thereby providing greater “interparticulate bonding” as compared with the neat drugs. Optimum particle size range of ascorbic acid and potassium chloride for satisfactory compactibility was found to be 30-40 μm and 20-40 μm, respectively. The present study demonstrates the importance of selecting the appropriate particle size of drug for the development of tablet dosage forms.     

Formulation and Release Kinetics of Sustained Release Phenylpropanolamine Hydrochloride Granules and Tablets

Abstract

Sustained release phenylpropanolamine hydrochloride (PPH) granules and tablets were prepared using HPMC, HPMC and SCMC, Eudragit RS, Eudragit RS+L or HPMC + Eudragit RS matrices. The release pattern of PPH from the prepared granules and tablets was found to be in the following order HPMC > HPMC + SCMC > RS > RS + 1> HPMC + RS. The results revealed that, although the drug concentration was kept constant in all the prepared granules and tablets, the drug release from these formulations was clearly different and depends mainly on the type of matrix used. The presence of Eudragit L with Eudragit RS and Eudragit RS with HPMC resulted in a marked decrease in the drug release compared with that obtained from the matrix containing HPMC or Eudragit RS alone. The release data of PPH from the prepared granules and tablets were treated mathematically according to zero order, first order, Langenbuchar, modified Langenbucher and Higuchi models. The results revealed that no one model was able adequately to describe the drug release profiles from these formulations. In-vivo studies in human volunteers showed that, the peak urinary excretion of PPH occurred over a sustained period from 2 to 6.5 hr in case of HPMC + SCMC tablets and from 2 to 10 hr in case of either RS+L or HPMC + RS tablets.     

Influence of Dissolution Medium Agitation on Release Profiles of Sustained-Release Tablets

Reaching nearly perfect sink conditions is very important in the determination of drug dissolution rates. Many times, the only factor that is taken into consideration in achieving sink conditions is the relation between the drug concentration and its solubility. The analytical conditions of the dissolution assay, as well as the dissolution apparatus, stirring speed, and nature and volume of the dissolution fluid may also influence the dissolution results. The main objective of this work was to study the influence of the stirring rate conditions and of the dissolution apparatus in the diltiazem hydrochloride release from tablets. Diltiazem hydrochloride sustained-release (SR) tablets were tested and the following dissolution parameters were evaluated: t_10%, t_25%, t_50%, dissolution time, mean dissolution time (MDT), and dissolution efficiency (DE) at t₁₂₀, and at t₃₆₀. To analyze the release mechanism, several release models were tested, such as Higuchi, zero order, first order, Baker-Lonsdale, Hixson-Crowell, Weibull, and Korsmeyer-Peppas. The similarities between two in vitro dissolution profiles were assessed by the similarity factor f₂. The in vitro release kinetics of diltiazem hydrochloride sustained-release tablets were evaluated using the USP 2 (paddle) and USP 4 (flow-through) apparatus.     

Formulation and Evaluation of Paracetamol 500 G Tablets Produced by a New Direct Cranulation Method

Currendy there are three general methods available for producing tablets. These methods are (a) direct compression, (b) double compression or slugging, and (c) wet granulation. The simplest method is direct compression, since the drug need only be mixed with a suitable free flowing exeipieut and compressed directly into tablets. The process has obvious advantages since the use of a binding agent is avoided and no drying at all is required. As a result it can be used to tablet hydrolysable and theroolabile drugs. Even though it does have many advantages, it also has limitations concerning capacity, colouration and segregation. Perhaps the most serious disadvantage is the segregation of components during handling. no further lubricant was added since the granules were effectively self-lubricating. Compression of the granules was effected on a Maneaty F3 instrumented machine between J “punches at 47, 102 and 215 MNm”². 20 tablets from each batch were individually weighed and the mean, the standard deviation, and the coefficient of variation evaluated.     

Stereoselective release behaviors of imprinted bead matrices

In this work, the stereoselective release behaviors of “low”-swelling molecularly imprinted polymer (MIP) bead matrices in pressed-coat tablet type were studied. Either R-propranolol selective MIP or S-propranolol selective MIP was combined with excipients and racemic propranolol and fabricated into the matrix. Subsequently, the release of different propranolol enantiomers from the matrices was examined. Also, the microscopic structure of the hydrated “low”-swelling MIP matrix was determined using a cryogenic scanning electron microscope in order to compare with that of the hydrated “high”-swelling MIP matrix. In vitro release profiles of the “low”-swelling matrices showed a difference in the release of enantiomers, in that the non-template isomer was released faster than the template isomer. However, in the last phase of dissolution this difference reduced and later reversed, resulting at last in the type of specificity being similar to that obtained previously with “high”-swelling MIP matrices.

n summary, MIP beads can be fashioned into matrices and incorporated into different formulations to regulate the resultant stereoselectivity. From the behaviors of stereoselective release observed in MIP matrices, we can conclude that the enantioselective-controlled delivery mechanism of MIPs via formulations depends on the relative affinity of the enantiomer for the template sites, as well as the nature of the polymer, such as hydrophobicity and swellability.