Immediate-release Dosage Forms Research Articles

Formulation Strategies for Sustained-Release Tablet Dosage Forms

Sustained-release or extended-release tablet formulations are designed to release the active pharmaceutical ingredient at a slower rate and over an extended period compared to conventional immediate-release dosage forms. This controlled drug delivery approach offers several advantages including improved patient compliance, maintenance of therapeutic drug levels, reduced side effects, and protection of drug molecules from degradation. [1,2] Various formulation approaches have been explored for achieving sustained drug release from tablet matrices. This review discusses key formulation aspects like rate-controlling polymers, factors influencing drug release, manufacturing techniques, and recent advances aided by quality-by-design principles and mathematical modeling for optimizing sustained-release profiles. Regulatory considerations for evaluation and approval are also highlighted

In Vitro Simulation of the Fasted Gastric Conditions and Their Variability to Elucidate Contrasting Properties of the Marketed Dabigatran Etexilate Pellet-Filled Capsules and Loose Pellets.

Variability of the gastrointestinal tract is rarely reflected in in vitro test protocols but often turns out to be crucial for the oral dosage form performance. In this study, we present a generation method of dissolution profiles accounting for the variability of fasted gastric conditions. The workflow featured 20 biopredictive tests within the physiological variability. The experimental array was constructed with the use of the design of experiments, based on three parameters: gastric pH and timings of the intragastric stress event and gastric emptying. Then, the resulting dissolution profiles served as a training data set for the dissolution process modeling with the machine learning algorithms. This allowed us to generate individual dissolution profiles under a customizable gastric pH and motility patterns. For the first time ever, we used the method to successfully elucidate dissolution properties of two dosage forms: pellet-filled capsules and bare pellets of the marketed dabigatran etexilate product Pradaxa. We showed that the dissolution of capsules was triggered by mechanical stresses and thus was characterized by higher variability and a longer dissolution onset than observed for pellets. Hence, we proved the applicability of the method for the in vitro and in silico characterization of immediate-release dosage forms and, potentially, for the improvement of in vitro-in vivo extrapolation.

Chemical Composition and Insulin-Resistance Activity of Arginine-Loaded American Cranberry (Vaccinium macrocarpon Aiton, Ericaceae) Leaf Extracts.

One of the key pathogenetic links in type 2 diabetes mellitus (T2DM) is the formation of insulin resistance (IR). Besides a wide selection of synthetic antidiabetic drugs, various plant-origin extracts are also available to support the treatment of T2DM. This study aimed to investigate and gain knowledge of the chemical composition and potential IR correction effect of American cranberry (Vaccinium macrocarpon Aiton) leaf extracts and formulate novel 3D-printed oral dosage forms for such extracts. The bioactivity and IR of L-arginine-loaded cranberry leaf extracts were studied in vivo in rats. The cranberry leaf extracts consisted of quinic, 3-caffeoylquinic (chlorogenic), p-coumaroylquinic acids, quercetin 3-O-galactoside, quercetin-3-O-glucoside, quercetin-3-xyloside, quercetin-3-O-arabino pyranoside, quercetin-3-O-arabinofuranoside, quercetin 3-O-rhamnoside, and quercetin-O-p-coumaroyl hexoside-2 identified by HPLC. In vivo studies with rats showed that the oral administration of the cranberry leaf extracts had a positive effect on insulin sensitivity coefficients under the insulin tolerance test and affected homeostasis model assessment IR levels and liver lipid content with experimental IR. A novel 3D-printed immediate-release dosage form was developed for the oral administration of cranberry leaf extracts using polyethylene oxide as a carrier gel in semi-solid extrusion 3D printing. In conclusion, American cranberry leaf extracts loaded with L-arginine could find uses in preventing health issues associated with IR.

Immediate-release dosage form; focus on disintegrants use as a promising excipient

Disintegrants are materials or mixtures of substances added in the drug formulations, which make easier dispersion or breakup of tablets and ingredients of capsules in small-scale particles for fast dissolution then it comes in contact with water in the GI tract. Immediate drug release dosage forms disintegrate rapidly after administration with an enhanced rate of dissolution. The superdisintegrants provide instantaneous disintegration of tablets after administration in the stomach. In this field, immediate-release liquid dosage forms and parenteral dosage forms have also been introduced for treating patients. The oral route is the most convenient route for the administration of solid dosage form, about 85% of solid dosage is administered by the oral route because of its advantages over others. The therapeutic activity of these formulations is obtained through a typical manner like disintegration followed by dissolution. Hence disintegration has a major role in facilitating drug activity. Diverse categories of superdisintegrants such as synthetic, semi-synthetic, natural, co-processed blends, multifunctional superdisintegrants, etc. have been employed to develop effectual orodispersible tablets and to overcome the limitations of conventional tablet dosage forms. The objective of the present review article is to highlight the various kinds of traditional, Natural crude drugs containing gum and mucilage, Co-processed, semisynthetic and synthetic disintegrants along with a concentration in tablet and capsule disintegration and effect on drug release, which are being used in the formulation to provide the safer, effective drug delivery with patient compliance. Also highlights the mechanism and use of disintegrants in the immediate release dosage form.
 Keywords: Disintegrants, Natural, Co-processed, Immediate release

Investigation on the use of fused deposition modeling for the production of IR dosage forms containing Timapiprant

The present work focused on evaluating the feasibility of fused deposition modeling (FDM) in the development of a dosage form containing Timapiprant (TMP), also known as CHF6532, which is a novel active molecule indicated in the potential treatment of eosinophilic asthma upon oral administration. The resulting product could be an alternative, with potential towards personalization, of immediate release (IR) tablets used in the clinical studies. Formulations based on different polymeric carriers were screened, leading to the identification of a polyvinyl alcohol-based one, which turned out acceptable for versatility in terms of active ingredient content, printability and dissolution performance (i.e. capability to meet the dissolution specification set, envisaging >80% of the drug dissolved within 30 min). Following an in-depth evaluation on the influence of TMP solid state and of the voids volume resulting from printing on dissolution, few prototypes with shapes especially devised for therapy customization were successfully printed and were compliant with the dissolution specification set.

Comparison of Dissolution profile for Immediate-Release Dosage form for US and Europe

Any oral medication product control strategy must include the creation of a dissolve method with appropriate specifications. In the creation of drug, dissolution testing is critical IV approach. In some cases, an IV dissolution test can be used instead of an in vivo dissolution test. As a result, regulatory agencies have formally acknowledged in vitro methods to determine the dissolution frequency of API from the solid oral form as a significant factor when manufacturing solid-oral-dosage forms. Dissolution tests have long been acknowledged as critical quality-control tools for ensuring batch-to-batch consistency. Following post-approval changes to pharmaceutical products, dissolution testing is also important in providing quality information of the product.

Medication-administration-via-enteral-feeding-tubes-a-survey-of-nurses-knowledge-and-practice

Introduction: Enteral feeding is a type of nutritional support for critically ill patients who are unable to tolerate oral feeding. It is vital to ensure that nurses practise proper administration techniques via enteral feeding tubes (EFT) to ensure that medications can be delivered safely and effectively. Objective: This study aims to assess the knowledge and practice of nurses on medication administration through EFT. The association between demographics and knowledge was also explored. Method: This study is a cross-sectional, self-administered, content-validated, pre-tested questionnaire survey involving all nurses who worked in the ward setting at Hospital Queen Elizabeth II from August to December 2020. Result: A total of 409 questionnaires were sent out with 252 responses received. The majority of respondents were female (n = 240, 95.6%) with a median working experience of 84 months (interquartile range of 44 months). Most nurses knew that the immediate-release dosage forms (n = 237, 94.4%) may be crushed and administered through EFT. Similarly, most nurses were aware that sublingual nitroglycerin (GTN) tablets should not be crushed (n = 232, 92.8%) and that nystatin suspension should not be administered via EFT (n = 212, 85.1%). However, about half of the nurses responded incorrectly when questioned about the particulars of EFT involving the administration of sustained-release medications (n = 152, 60.6%), soft gelatin capsules (n = 111, 44.4%) and hard gelatin capsules (n = 102, 40.6%). Meanwhile, in terms of practice, a majority of the nurses would correctly routinely flush the EFT before (n = 226, 90.4%) and after (n = 245, 98.8%) the administration of medications. However, only a small proportion of nurses (n = 43, 17.3%) demonstrated the appropriate practice of administering all medications separately all the time. Furthermore, it was also worth noting that for some specific knowledge-based questions, nurses from the intensive care setting had more correct responses when compared to those from the general ward setting (p < 0.05). Conclusion: The knowledge gap and inconsistencies in practices amongst nurses related to the use of EFT may lead to suboptimal delivery of medications, whilst potentially compromising patient outcomes. Hence, continuous educational programs should be carried out to ensure safe and effective drug administration through EFT.

Different aspects of polymers – A review article

Polymers play vital roles in the dosage developments of immediate release dosage forms and modified release dosage forms. In different drug delivery systems, polymers are used to develop the dosage forms which are designed to control the release of the therapeutic agent at a constant dose for long time intervals that decrease the cyclic dosages. It is widely used as excipients in formulating various dosage designs to aid the bulk amount so that the drug gets trapped. Immediate-release dosage forms consist of tablets and capsules and modified release dosage forms consist of extended-release dosage forms and gastro retentive release dosage forms. Different modifications are performed with polymers to make conjugates such as polymer-drug and polymer-protein conjugates which are widely used as polymeric carriers in biological applications. Polymers are the backbones of pharmaceuticals drug delivery that are designed to control drugs released through different medical devices such as implants. In biological applications, biodegradable polymers are widely due to having good biocompatibility properties with other therapeutic agents and well-known biodegradability properties. It provides resistance to the drugs from the biological environment and prolongs the drug's release so that it achieves its stability. Different biocompatibility tests are performed in-vivo and in-vitro for both natural as well as synthetic biodegradable polymers that are used in the dosage form and biomedical applications.

Statistical Inference of the Probability of Passing the USP Dissolution Test

In pharmaceutical manufacturing, dissolution test for immediate-release dosage forms is routinely performed to ensure the drug products conform to the quality standard specified in the United States Pharmacopeia and National Formulary (USP/NF). The USP dissolution test is a complex three-stage dissolution test involving the inference of individual dissolution measurement or/and sample mean of dissolution measurement of all dosage units. Passing the USP dissolution test once does not necessarily assure that the same batch of drug products would pass again if tested later. For the purpose of inferring the dissolution quality of a batch of drug products, a statistical inference based on acceptance limit is considered. The statistical inference assures a high probability of passing the USP dissolution test with a prescribed level of confidence. There is no closed-form expression of the true probability of passing the USP dissolution test. In the literature, the true probabilities of passing the USP dissolution test are usually approximated based on the lower probability bound. The available statistical inferential procedures based on the lower probability bound give an approximate and conservative inference. In this article, we propose the derivation of the true probability of passing the USP dissolution test based on the numerical computation. The probabilities of passing the USP dissolution test derived from the proposed numerical computation are no appreciable difference from the simulated true probabilities. The statistical inferential procedure via acceptance limits for various sample sizes of dissolution measurements and probabilities of passing the USP dissolution test is also provided.

Integrating theoretical and experimental permeability estimations for provisional biopharmaceutical classification: Application to the WHO essential medicines.

The accuracy of the provisional estimation of the Biopharmaceutics Classification System (BCS) is heavily influenced by the permeability measurement. In this study, several theoretical and experimental models currently employed for BCS permeability classification have been analysed. The experimental models included the in situ rat intestinal perfusion, the ex vivo rat intestinal tissue in an Ussing chamber, the MDCK and Caco-2 cell monolayers, and the parallel artificial membrane (PAMPA). The theoretical models included the octanol-water partition coefficient and the QSPeR (Quantitative Structure-Permeability Relationship) model recently developed. For model validation, a dataset of 43 compounds has been recompiled and analysed for the suitability for BCS permeability classification in comparison with the use of human intestinal absorption and oral bioavailability values. The application of the final model, based on a majority voting system showed a 95.3% accuracy for predicting human permeability. Finally, the present approach was applied to the 186 orally administered drugs in immediate-release dosage forms of the WHO Model List of Essential Medicines. The percentages of the drugs that were provisionally classified as BCS Class I and Class III was 62.4%, suggesting that in vivo bioequivalence (BE) may potentially be assured with a less expensive and more easily implemented in vitro dissolution test, ensuring the efficiency and quality of pharmaceutical products. The results of the current study improve the accuracy of provisional BCS classification by combining different permeability models.

Salt formation improved the properties of a candidate drug during early formulation development

The purpose of this study was to investigate if AZD5329, a dual neurokinin NK1/2 receptor antagonist, is a suitable candidate for further development as an oral immediate release (IR) solid dosage form as a final product. The neutral form of AZD5329 has only been isolated as amorphous material. In order to search for a solid material with improved physical and chemical stability and more suitable solid-state properties, a salt screen was performed. Crystalline material of a maleic acid salt and a fumaric acid salt of AZD5329 were obtained. X-ray powder diffractiometry, thermogravimetric analysis, differential scanning calorimetry and dynamic vapor sorption were used to investigate the physicochemical characteristics of the two salts. The fumarate salt of AZD5329 is anhydrous, the crystallization is reproducible and the hygroscopicity is acceptable. Early polymorphism assessment work using slurry technique did not reveal any better crystal modification or crystallinity for the fumarate salt. For the maleate salt, the form isolated originally was found to be a solvate, but an anhydrous form was found in later experiments; by suspension in water or acetone, by drying of the solvate to 100–120 °C or by subjecting the solvate form to conditions of 40 °C/75%RH for 3 months. The dissolution behavior and the chemical stability (in aqueous solutions, formulations and solid-state) of both salts were also studied and found to be satisfactory. The compound displays sensitivity to low pH, and the salt of the maleic acid, which is the stronger acid, shows more degradation during stability studies, in line with this observation. The presented data indicate that the substance fulfils basic requirements for further development of an IR dosage form, based on the characterization on crystalline salts of AZD5329.

Biorelevant drug release of Metformin dosage forms using complementary in vitro tools

Drug release from immediate release (IR) and extended release (ER) metformin products was investigated using the Dow Chemical Company’s FloVitroTM biorelevant dissolution instrument. This was complemented by using the Sirius SDi2 (Surface Dissolution Imaging) platform to investigate mechanistic differences accounting for drug release. Level A IVIVC was demonstrated for metformin IR dosage forms, using FloVitroTM, whilst ER tablets demonstrated lower Cmax and Tmax using the same method. The SDi2 showed disintegration as the main release mechanism for IR tablets, whilst swelling and drug diffusion was observed for ER tablets. FloVitroTM and SDi2 technologies can be used to compare behaviour of formulations during dosage form selection

Application of factorial design approach in development and evaluation of self microemulsifying drug delivery system (SMEDDS) of mebendazole

Self microemulsifying drug delivery systems (SMEDDS) are defined as isotropic mixtures of natural or synthetic oils, surfactants and co-solvents/co-surfactants. Upon mild agitation followed by dilution in aqueous media, such as GI fluids, these systems can form fine oil in water o/w microemulsion. The purpose of this study was to formulate SMEDDS containing mebendazole. Labrafil M2125 CS (an oil), Tween 20 (a surfactant), and Maisine 35-1 (a cosurfactant) were used to formulate SMEDDS. Effect of concentrations of oil and surfactant on emulsification process and in vitro drug release (percent cumulative drug release) was studied using 32 factorial design. Multiple regression analysis data and response surfaces obtained showed that viscosity increased significantly with increasing amount of co-surfactant. Whereas, decrease in emulsification time, it may decreases average droplet size of resultant microemulsion and rapid drug release. The drug release from the formulation increased with increasing amount of surfactant concentration increases solubility of drug in system. Prepared SMEDDS produced acceptable properties of immediate-release dosage forms. The L5 formulation was found to be optimized on basis of high percent cumulative drug release. And it is evaluated by globule size and zeta potential indicates globule size is in micrometer range and good stable formulation. It may expect to increase the bioavailability of mebendazole as solubility enhances.

Controlled release drug delivery systems to improve post-operative pharmacotherapy.

Over 230 million surgical procedures are conducted worldwide each year with numbers increasing. Pain, undesirable inflammation and infection are common complications experienced by patients following surgery. Opioids, non-steroidal anti-inflammatory drugs (NSAIDs), local anaesthetics (LAs) and antibiotics are the commonly administered drugs peri-operatively to manage these complications. Post-operative pharmacotherapy is typically achieved using immediate-release dosage forms of drugs, which lead to issues around fluctuating plasma concentrations, systemic adverse effects and poor patient adherence. Controlled release (CR) systems for certain medicines including opioids, NSAIDs and antibiotics have demonstrably enhanced treatment efficacy in the post-surgical setting. However, challenges remain to ensure patient safety while achieving individual therapeutic needs. Newer CR systems in the research and development pipeline have a high level of control over medicine release, which can be initiated, tuned or stopped on-demand. Future systems will self-regulate drug release in response to biological markers providing precise individualized therapy. In this review, we cover currently adopted CR systems in post-operative pharmacotherapy, including drug eluting medical devices, and highlight a series of examples of novel CR technologies that have the potential for translation into post-surgical settings to improve medication efficacy and enhance post-surgical recovery.

Few Drugs Display Flip-Flop Pharmacokinetics and These Are Primarily Associated with Classes 3 and 4 of the BDDCS

This study was conducted to determine the number of drugs exhibiting flip-flop pharmacokinetics following oral (p.o.) dosing from immediate-release dosage forms and if they exhibit a common characteristic that may be predicted based on BDDCS classification. The literature was searched for drugs displaying flip-flop kinetics (i.e., absorption half-life larger than elimination half-life) in mammals in PubMed, via internet search engines and reviewing drug pharmacokinetic data. Twenty two drugs were identified as displaying flip-flop kinetics in humans (13 drugs), rat (nine drugs), monkey (three drugs), horse (two drugs), and/or rabbit (two drugs). Nineteen of the 22 drugs exhibiting flip-flop kinetics were BDDCS Classes 3 and 4. One of the three exceptions, meclofenamic acid (Class 2), was identified in the horse; however, it would not exhibit flip-flop kinetics in humans where the p.o. dosing terminal half-life is 1.4 h. The second, carvedilol, can be explained based on solubility issues, but the third sapropterin dihydrochloride (nominally Class 1) requires further consideration. The few drugs displaying p.o. flip-flop kinetics in humans are predominantly BDDCS Classes 3 and 4. New molecular entities predicted to be BDDCS Classes 3 and 4 could be liable to exhibit flip-flop kinetics when the elimination half life is short and should be suspected to be substrates for intestinal transporters.

PQRI Workshop Report: Application of IVIVC in Formulation Development

This article summarizes the proceeding of the September 2012 Workshop on Application of In vitro–In vivo correlation (IVIVC) in Formulation Development. The workshop brought together international experts with the goal of establishing common concepts that could be utilized to facilitate the development and validation of IVIVCs in the registration of and post-approval changes to oral solid dosage forms. The workshop was organized by the Product Quality Research Institute (PQRI) and cosponsored by AAPS, FDA, FIP, and USP. Open access of this information is available to all interested parties. INTRODUCTION IVIVC is an important concept and a tool in the development and evaluation of pharmaceutical dosage forms. A properly conducted IVIVC provides assurance of the robustness of a dosage form and provides justification of manufacturing changes during drug product development. A filed IVIVC can accelerate internal decision making of proposed SUPAC changes by providing linkage back to preapproval formulations. As such, a well-conducted IVIVC may have substantial value to pharmaceutical manufacturers, regulatory bodies, and ultimately, consumers of the product. Early history (1982–1992) suggests that few IVIVCs were filed. Since the advent of the FDA guidance (1) approximately fifteen years ago, the number of NDAs containing IVIVC studies has increased, and it is anticipated that exploration of IVIVCs and IVIVRs will continue to grow. FDA scientists confirmed that most IVIVCs filed are for modified-release (MR) products with fewer for immediaterelease (IR) dosage forms. Many of the latter were identified as insufficient and not approvable. Early statistics immediately following the issuance of the FDA Guidance *Corresponding author. e-mail: vanbuskirk@drugdevconsult.com dx.doi.org/10.14227/DT210214P51

Molecular investigations into vaginal immunization with HIV gp41 antigenic construct H4A in a quick release solid dosage form

A robust vaginal immune response is considered essential for an effective prophylactic vaccine that prevents transmission of HIV and other sexually acquired diseases. Considerable attention has recently focused on the potential of vaginally administered vaccines as a means to induce such local immunity. However, the potential for vaccination at this site remains in doubt as the vaginal mucosa is generally considered to have low immune inductive potential. In the current study, we explored for the first time the use of a quick release, freeze-dried, solid dosage system for practical vaginal administration of a protein antigen. These solid dosage forms overcome the common problem associated with leakage and poor retention of vaginally administered antigen solutions. Mice were immunized vaginally with H4A, an HIV gp41 envelope based recombinant protein, using quick release, freeze-dried solid rods, and the immune responses compared to a control group immunized via subcutaneous H4A injection. Vaginally immunized mice failed to elicit robust immune responses. Our detailed investigations, involving cytokine analysis, the stability of H4A in mouse cervicovaginal lavage, and elucidation of the state of H4A protein in the immediate-release dosage form, revealed that antigen instability in vaginal fluid, the state of the antigen in the dosage form, and the cytokine profile induced are all likely to have contributed to the observed lack of immunogenicity. These are important factors affecting vaginal immunization and provide a rational basis for explaining the typically poor and variable elicitation of immunity at this site, despite the presence of immune responsive cells within the vaginal mucosae. In future mucosal vaccine studies, a more explicit focus on antigen stability in the dosage form and the immune potential of available antigen-responsive cells is recommended.

An observational study of once-daily modified-release methylphenidate in ADHD: quality of life, satisfaction with treatment and adherence

Attention deficit hyperactivity disorder (ADHD) impacts significantly on the quality of life (QoL) of patients and their families. Choice of therapy is increasingly influenced by treatment satisfaction and patient preference, with once-daily modified-release methylphenidate (MPH-MR) formulations offering clear benefits compared with immediate-release (IR) dosage forms. The effects of MPH-MR on QoL in ADHD have not been widely investigated and need more clarity in practice. The open-label OBSEER study evaluated the effectiveness and tolerability of Equasym XL®, a MPH-MR formulation, in routine practice. Children and adolescents (aged 6–17 years) with ADHD and attending school were included if Equasym XL® treatment was planned by the treating physician. Physicians, parents and patients completed questionnaires assessing QoL (KINDL; parent, child or adolescent versions), satisfaction with medication, adherence and treatment tolerability at baseline (Visit 1), 1–3 weeks (Visit 2) and 6–12 weeks (Visit 3) over a maximum 3-month observation period. Data from 822 consecutively referred patients were analysed. QoL and medication satisfaction increased from Visit 1 to Visit 3, with both patients and parents rating therapy with Equasym XL® as better than previous drug therapy. KINDL total score effect sizes were 0.67 (parents’ ratings), 0.52 (children’s ratings) and 0.51 (adolescents’ ratings; all p < 0.001). All KINDL subscores also increased: both parents and patients had the greatest improvement for school. Adherence to Equasym XL® was frequently rated as superior to prior treatment, particularly compared with MPH-IR repeated dosing. Treatment was generally well tolerated; approximately 3% of the patients discontinued treatment due to adverse events. Equasym XL® improved QoL compared with prior therapy, and resulted in good medication satisfaction and adherence in drug-naïve and previously treated patients.

An Investigation into the Influence of Experimental Conditions on In Vitro Drug Release from Immediate-Release Tablets of Levothyroxine Sodium and Its Relation to Oral Bioavailability

The aim of this study was to investigate the influence of experimental conditions on levothyroxine sodium release from two immediate-release tablet formulations which narrowly passed the standard requirements for bioequivalence studies. The in vivo study was conducted as randomised, single-dose, two-way cross-over pharmacokinetic study in 24 healthy subjects. The in vitro study was performed using various dissolution media, and obtained dissolution profiles were compared using the similarity factor value. Drug solubility in different media was also determined. The in vivo results showed narrowly passing bioequivalence. Considering that levothyroxine sodium is classified as Class III drug according to the Biopharmaceutics Classification System, drug bioavailability will be less sensitive to the variation in its dissolution characteristics and it can be assumed that the differences observed in vitro in some of investigated media probably do not have significant influence on the absorption process, as long as rapid and complete dissolution exists. The study results indicate that the current regulatory criteria for the value of similarity factor in comparative dissolution testing, as well as request for very rapid dissolution (more than 85% of drug dissolved in 15 min), are very restricted for immediate-release dosage forms containing highly soluble drug substance and need further investigation. The obtained results also add to the existing debate on the appropriateness of the current bioequivalence standards for levothyroxine sodium products.

Bioavailability and in-vitro/in-vivo correlation for propranolol hydrochloride extended-release bead products prepared using aqueous polymeric dispersions.

The influence of formulation and extrinsic factors has been investigated for the in-vitro release of propranolol hydrochloride from controlled-release beads prepared using aqueous polymeric dispersions, Aquacoat and Surelease. A single-dose three-way crossover bioavailability study of two extended-release experimental formulations (80 mg), Inderal LA (80 mg) and an Inderal immediate-release dosage form (2 x 40 mg) was also conducted and a comparative analysis of pharmacokinetic parameters and the in-vitro release profiles was performed to assess in-vitro/in-vivo correlation. Analysis showed that the in-vitro release data appeared to follow zero-order release kinetics. Intensity of agitation and dissolution method were found to have no significant effect on drug release from beads prepared using either of the coating dispersions studied or Inderal LA. Release of drug from beads coated with Aquacoat was faster in basic media than in acidic media; Surelease-coated beads, however, showed release characteristics that were less sensitive to changes in the pH of the dissolution fluid, and Inderal LA beads showed slower release profiles in acidic medium than in other dissolution media studied. Pharmacokinetic analysis of the data revealed sustained-release absorption characteristics without any evidence of dose-dumping from any of the extended-release dosage forms studied. Regression analysis of the fraction of drug absorbed against the percentage of the drug released in-vitro, at the corresponding times, yielded good in-vitro/in-vivo correlation (level A) for all the extended-release formulations studied. The results showed that there was no dose-dumping from any of extended-release formulations and that the relative bioavailabilities of the experimental formulations were superior to that of the marketed formulation.