Design and evaluation of a dry coated drug delivery system with an impermeable cup, swellable top layer and pulsatile release

Development and Evaluation of Compression Coating Gastro-Floating Tablet of Alfuzosin Hydrochloride for Zero-Order Controlled Release

Alfuzosin hydrochloride is an appropriate candidate drug to prepare a gastro-retention controlled release dosage form since it demonstrates a narrow absorption window in the proximal section of the gastrointestinal tract with a short half-life. The purpose of the present study was to develop and optimize a gastro-floating tablet of alfuzosin hydrochloride by using the compression coating method for controlling drug release in a controlled manner. The floating tablets were developed utilizing hydroxypropyl methylcellulose and carbomer as matrix materials. The impact of formulation factors on buoyancy property and in vitro drug release of the floating tablet was investigated. The "similarity factor" (f₂) was used as the indicator for the optimization of the formulations. Furthermore, in vivo pharmacokinetic study in rabbits and correlation of in vitro/in vivo study were also performed. It was found that the optimized formulation F9 could float immediately less than 2 min and remain lastingly buoyant over 24 h and follow zero-order release kinetics well. In comparison with the commercially available prolonged release tablets XATRAL® XL, the prepared floating tablet exhibited similar pharmacokinetic parameters (C_max, T_max, t_1/2, and AUC_0 - t) and plasma concentration versus time profile. Moreover, it indicated from the correlation of in vitro/in vivo study that the floating tablets exhibited a good correlation of in vitro/in vivo. In summary, the compression coating gastro-floating tablets might be a promising drug delivery system for alfuzosin hydrochloride to control drug release.

Tablets of paliperidone using compression-coated technology for controlled ascending release

The aim of this work was to prepare ascending release compression-coated (CC) tablets with paliperidone (PAL) using a simple manufacturing technique and short manufacturing process. The release behavior and mechanisms in vitro of the final tablets was investigated and evaluated. The PAL CC tablets were comprised of a core layer of high viscosity hydroxypropyl cellulose (HPC-H) and a coating layer of high viscosity hydroxypropyl methylcellulose (HPMC-K100M). Several factors such as materials and core tablet compositions were studied for their influence in the formulation procedure. The drug release mechanism was studied using gravimetric analysis. The data could be fitted to the Peppas model. The ascending drug release results were expressed in terms of the slope of the release curve at different time points. Results showed that the formulation could achieve a good ascending drug release when the weight ratio of PAL was 5:1 (core:layer). The fraction of HPC and HPMC was 33 %, and the combination of Eudragit RL-PO was 10%. The ascending release mechanism was due to solvent penetration into the PAL CC tablets, and subsequent drug dissolution from the gelatinous HPC and HPMC matrix erosion. The release mechanism was therefore a combination of diffusion and erosion. This work demonstrated that the compression-coated tablets could achieve controlled ascending release over 24 h for the oral administration systems.

Design of a Time-Controlled Pulsatile Release System for Propranolol Using the Dry-Coated Method: In Vitro and In Vivo Evaluation

The objective of this study was to design a time-controlled pulsatile release (TCPR) system containing propranolol (PNH) as an active pharmaceutical ingredient. Here, the developed dosage forms were coated with hydroxypropyl-methylcellulose (HPMC) and other excipients as barrier layer using dry-coated technology. The influence of HPMC, microcrystalline cellulose (MCC), and lactose in the outer coating and the coating weight on drug release were investigated. Then, a three-factor, five-level central composite design (CCD) and response surface method were used to optimize the formula of the coating. After data processing, the optimal prescription was found to be as follows: HPMC E50(X₁) 86.2 mg, MCC(X₂) 43.8 mg, and lactose (X₃) 21.3 mg in the coating. Moreover, the in vitro tests showed that the optimized formulation of TCPR had a lag time of 4 h followed by a 4-h drug release. Also, determination of the extent of erosion of the TCPR tablets revealed that the lag time is related to the coating erosion speed. The in vivo test in beagle dogs and comparison of the parameters for the TCPR tablets and reference preparations showed significant differences for T_max (7.83 ± 0.408 and 2 ± 0.00) and C_max (185.45 ± 28.561 and 587 ± 45.27 ng/ml) but no significant differences in the AUC_0-∞ (1757.876 ± 208.832 and 1779.69 ± 229.02 ng h/ml). These results demonstrated that the TCPR tablets successfully prolonged the lag time and controlled the release of propranolol.

Development of press-coated, floating-pulsatile drug delivery of lisinopril

Lisinopril is an angiotensin-converting enzyme (ACE) inhibitor, primarily used for the treatment of hypertension, congestive heart failure, and heart attack. It belongs to BCS class III having a half-life of 12 hrs and 25% bioavailability. The purpose of the present work was to develop a press-coated, floating-pulsatile drug delivery system. The core tablet was formulated using the super-disintegrants crosprovidone and croscarmellose sodium. A press-coated tablet (barrier layer) contained the polymer carrageenan, xanthan gum, HPMC K4M, and HPMC K15M. The buoyant layer was optimized with HPMC K100M, sodium bicarbonate, and citric acid. The tablets were evaluated for physical characteristics, floating lag time, swelling index, FTIR, DSC, and in vitro and in vivo behavior. The 5% superdisintgrant showed good results. The FTIR and DSC study predicted no chemical interactions between the drug and excipients. The formulation containing xanthan gum showed drug retaining abilities, but failed to float. The tablet containing HPMC K15M showed a high swelling index. The lag time for the tablet coated with 200 mg carrageenan was 3±0.1 hrs with 99.99±1.5% drug release; with 140 mg HPMC K4M, the lag time was 3±0.1 hrs with 99.71±1.2% drug release; and with 120 mg HPMC K15M, the lag time was 3±0.2 hrs with 99.98±1.7% drug release. The release mechanism of the tablet followed the Korsmeyer-Peppas equation and a first-order release pattern. Floating and lag time behavior have shown good in vitro and in vivo correlations.

A novel multilayered multidisk oral tablet for chronotherapeutic drug delivery

A Multilayered Multidisk Tablet (MLMDT) comprising two drug-loaded disks enveloped by three drug-free barrier layers was developed for use in chronotherapeutic disorders, employing two model drugs, theophylline and diltiazem HCl. The MLMDT was designed to achieve two pulses of drug release separated by a lag phase. The polymer disk comprised hydroxyethylcellulose (HEC) and ethylcellulose (EC) granulated using an aqueous dispersion of EC. The polymeric barrier layers constituted a combination of pectin/Avicel (PBL) (1st barrier layer) and hydroxypropylmethylcellulose (HPMC) (HBL1 and HBL2) as the 2nd and 3rd barrier layers, respectively. Sodium bicarbonate was incorporated into the diltiazem-containing formulation for delayed drug release. Erosion and swelling studies confirmed the manner in which the drug was released with theophylline formulations exhibiting a maximum swelling of 97% and diltiazem containing formulations with a maximum swelling of 119%. FTIR spectra displayed no interactions between drugs and polymers. Molecular mechanics simulations were undertaken to predict the possible orientation of the polymer morphologies most likely affecting the MLMDT performance. The MLMDT provided two pulses of drug release, separated by a lag phase, and additionally it displayed desirable friability, hardness, and uniformity of mass indicating a stable formulation that may be a desirable candidate for chronotherapeutic drug delivery.

On-off pulsed oral drug-delivery systems: a possible tool for drug delivery in chronotherapy

Circadian rhythms regulate most body functions and are important factors to consider when administering drugs. The existence of circadian rhythms in nature and their influences on human biological systems have given rise to the concept of chronotherapy, which is the science of delivering drugs in a synchronized manner with the rhythm-dependent circadian variation inherent in the human body. The safety and efficacy of a drug can be improved by matching the peak plasma concentration during a 24 h period of the rhythms. An on-off pulsed (pulsatile or time-controlled) release drug-delivery system offers rapid and transient release; stepwise release; and the sustained release of a certain amount of drug within a short time period after a predetermined off-release period according to the circadian rhythm of disease states. These systems deliver the drug at the right time and at an appropriate dosage and are the best approach for chronotherapy. These systems show promise for the optimal therapy of chronic diseases such as asthma, hypertension, myocardial infarction and arthritis, which show a circadian dependency. Various technologies have been adopted to mimic circadian rhythms in physiological functions and diseases. This review focuses on the basic concept of circadian rhythm, chronotherapy and recent advances in the development of on-off pulsed oral drug-delivery systems for optimal therapy.

Development and evaluation of a chronotherapeutic drug delivery system of torsemide

The objective of this study was to prepare and evaluate chronotherapeutic drug delivery systems (ChrDDs) of torsemide. Compression coated tablets (CCT) containing torsemide in the core tablet were prepared by the compression coating technique with different grades of polyethylene oxide (PEO WSR 301 & 1105). The optimized formulations were characterised for tabletting parameters and drug polymer interaction by Fourier-Transform Infrared Spectroscopy (FTIR).The hardness of all the CCT using PEO WSR 301 & PEO WSR 1105 were in the range 6-8 kg/cm² & 5.5 to 7 kg/cm² respectively. Their friability values were <0.3%. All the CCT showed a clear lag time but finalized as per the predetermined lag time. As the amount of PEO was increased in the outer layer the drug released was delayed. The drug content of all the CCT was >99%. The FTIR studies showed no interaction throughout the process of development. Formulations of F7 and of P7 were considered optimized formulations since they yielded a predetermined lag time of 6h before burst release. Hence, these formulations can be exploited to achieve chronotherapeutic drug delivery systems of Torsemide for the treatment of hypertension at the time the patient needs it.

Drug delivery technologies for chronotherapeutic applications

It has been proven that the body follows a 24-hour cycle called a circadian rhythm. This cycle is coordinated by the suprachiasmatic nucleus and controls nearly all bodily functions including those related to drug delivery. Knowledge of the body's circadian rhythm leads to an improved understanding of diseases and their treatment, known as chronotherapy, such that synchronizing drug application in accordance with the natural rhythm of the body leads to improved disease management and a greater patient therapeutic outcome. Chronotherapeutic diseases include asthma, cardiovascular diseases, glaucoma, rheumatoid arthritis and cancers. In order to treat these diseases numerous chronotherapeutic drug delivery systems have been developed, such that drug is released in the period when it is most needed. This review paper attempts to concisely explicate the role of circadian rhythms in various disease states and furthermore describes the various oral drug delivery technologies that have been employed for the treatment of chronotherapeutic diseases.

Novel/conceptual floating pulsatile system using high internal phase emulsion based porous material intended for chronotherapy

The aim of the present study was to design a novel/conceptual delivery system using ibuprofen, anticipated for chronotherapy in arthritis with porous material to overcome the formulation limits (multiple steps, polymers, excipients) and to optimize drug loading for a desired release profile suitable for in vitro investigations. The objective of this delivery system lies in the availability of maximum drug amount for absorption in the wee hours as recommended. Drug loading using 3(2) factorial design on porous carrier, synthesized by high internal phase emulsion technique using styrene and divinylbenzene, was done via solvent evaporation using methanol and dichloromethane. The system was evaluated in vitro for drug loading, encapsulation efficiency, and surface characterization by scanning electron, atomic force microscopy, and customized drug release study. This study examined critical parameters such as solvent volume, drug amount, and solvent polarity on investigations related to drug adsorption and release mostly favoring low-polarity solvent dichloromethane. Overall release in all batches ranged 0.98-52% in acidic medium and 71-94% in basic medium. These results exhibit uniqueness in achieving the least drug release of 0.98%, an ideal one, without using any release modifiers, making it distinct from other approaches/technologies for time and controlled release and for chronotherapy.

Modulation and optimization of drug release from uncoated low density porous carrier based delivery system

The purpose of this research work was to explore an application of uncoated porous drug carrier prepared by single-step drug adsorption for a delivery system based on integration of floating and pulsatile principles intended for chronotherapy. This objective was achieved by utilizing 3(2) factorial design, solvent volume (X(1)) and drug amount (X(2)) as selected variables, for drug adsorption using solvents, methanol, and dichloromethane (DCM), of varying polarity. Nitrogen adsorption (N(2)), scanning electron microscopy of cross-sections, and atomic force microscopy were done to study adsorption patterns and their effect on release pattern. Drug release study was customized by performing for 6 h in acidic environment to mimic gastroretention followed by basic environment akin to transit phase. Correlation between porous data from mercury and N(2) adsorption was probably studied for the first time. Observed regression analysis values for pore volume, surface area, and drug release indicated the influence of selected variables. Total release range in acidic medium was 12.77-24.57% for methanol, 8.79-15.26% for DCM, and final release of 69.45-92.23% for methanol, and 60.16-99.99% for DCM influenced by varying internal geometries was observed. Present form of drug delivery system devoid of any additives/excipients influencing drug release shows distinct behavior from other approaches/technologies in chronotherapy by (a) observing desired low drug release (8%) in acidic medium, (b) overcoming the limitations of process variables caused by multiple formulation steps and different characteristic polymers, (c) reducing time consumption due to single step process, and (d) extending as controlled/extended release.

Formulation approach for nicorandil pulsatile release tablet

The purpose of this study was to obtain a nicorandil pulsatile release tablet that has a well-regulated release lag time. When nicorandil is used as an antiangina drug, administration time control is important. A pulsatile release tablet is one of the effective approaches to modified release to reduce daily administration frequency. In this study, a pulsatile release tablet of nicorandil was formulated by fumaric acid dry coating around the core tablet including nicorandil. The model tablets, which had different content ratios of excipients in the dry-coating layer, were characterized by a dissolution test. The results showed that the release lag time was generated with fast release profiles. Various lag time controls of tablets were achieved, from 60 to 310 min on average, by variation of outer layer composition. From an analysis of the relation between lag times and outer layer composition, the key ingredient for prolongation of lag time was found to be fumaric acid. To analyze the lag time generation mechanism, water penetration for tablet was measured. The results indicated that the penetration depth was proportionate to the square root of time and the lag time formation mechanism was simple water penetration through the matrix of fumaric acid to the tablet core. The results also showed that the Washburn equation could be used to design the lag time of the pulsatile release tablet in this study. In conclusion, novel release control technology using fumaric acid was appropriate to obtain a nicorandil pulsatile release tablet that has well regulated lag time.

Modulation of a pulsatile release drug delivery system using different swellable/rupturable materials

Diclofenac sodium tablets consisting of core coated with two layers of swelling and rupturable coatings were prepared and evaluated as a pulsatile drug delivery system. Cores containing the drug were prepared by direct compression using microcrystalline cellulose and Ludipress as hydrophilic excipients with the ratio of 1:1. Cores were then coated sequentially with an inner swelling layer of different swellable materials; either Explotab, Croscarmellose sodium, or Starch RX 1500, and an outer rupturable layer of different levels of ethylcellulose. The effect of the nature of the swelling layer and the level of the rupturable coating on the lag time and the water uptake were investigated. Drug release rate studies were performed using USP paddle method. Results showed the dependence of the lag time and water uptake prior to tablet rupture on the nature of the swelling layer and the coating levels. Explotab showed a significant decrease in the lag time, followed by Croscarmellose sodium and finally by Starch RX 1500. Increasing the level of ethylcellulose coating retarded the diffusion of the release medium to the swelling layer and the rupture of the coat, thus prolonging the lag time.