Preparation and evaluation of sustained-release diltiazem hydrochloride pellets

Convolution- and Deconvolution-Based Approaches for Prediction of Pharmacokinetic Parameters of Diltiazem Extended-Release Products in Flow-Through Cell Dissolution Tester

The present study evaluated the effect of different configuration setups of the Flow-Through Cell (USP IV) dissolution tester in developing in vitro-in vivo correlation (IVIVC). A Biopharmaceutics Classification System (BCS) Class I Diltiazem (DTZ), formulated in extended-release (ER) gel-matrix system, was employed for this purpose. The study also assessed the validity and predictability of IVIVC employing both deconvolution- and convolution-based approaches. In vitro release was conducted in USP IV as open- or closed-loop setups, while the pharmacokinetic (PK) data were obtained from a previous fasted-state cross-over study conducted on 8 healthy male volunteers, after oral administration of ER matrix tablets against market product (Tildiem Retard® 90 mg). PK parameters (C_max, AUC_0-t and AUC_0-∞) were predicted, and compared with actual data to establish the strength of correlation models. Results showed that DTZ release from ER products was influenced by operating the FTC in different configuration-setups, where ≥ 75% of labeled DTZ was released after 6 h and 12 h using the open- and closed-loop settings, respectively. Correlation between fraction-dissolved versus fraction-absorbed for both ER products displayed linear relation upon employing FTC open-loop setup. Convolution-based approach was more discriminative in predicting DTZ in vivo PK parameters with a minimal prediction error, compared to deconvolution-based approach. A successful trial to predict DTZ PKs from individual in vitro data performed in USP IV dissolution model was established, employing convolution technique. Basic principle of the convolution approach provides a simple and practical method for developing IVIVC, hence could be utilized for other BCS Class I extended-release drug products.

In Vitro and In Vivo Evaluation of Oral Controlled Release Formulation of BCS Class I Drug Using Polymer Matrix System

Diltiazem hydrochloride is a calcium channel blocker, which belongs to the family of benzothiazepines. It is commonly used to treat hypertension and atrial fibrillation. Even though the drug has high solubility, its high permeability and rapid metabolism in the liver can limit the bioavailability and increase the dose frequencies for up to four times per day. This study focused on a polymer matrix system not only to control the drug release but also to prolong the duration of bioavailability. The polymer matrices were prepared using different ratios of poloxamer-188, hydroxypropyl methylcellulose, and stearyl alcohol. In vitro and in vivo assessments took place using 24 rabbits and the results were compared to commercially available product Tildiem® (60 mg tablet) as reference. Overall, the rate of drug release was sustained with the gradual increase of poloxamer-188 incorporated with hydroxypropyl methylcellulose and stearyl alcohol in the matrix system, achieving a maximum release period of 10 h. The oral bioavailability and pharmacokinetic parameters of diltiazem hydrochloride incorporated in polymer matrix system were similar to commercial reference Tildiem®. In conclusion, the combination of polymers can have a substantial effect on controlling and prolonging the drug release pattern. The outcomes showed that poloxamer-188 combined with hydroxypropyl methylcellulose and stearyl alcohol is a powerful matrix system for controlling release of diltiazem hydrochloride.

A Comprehensive Review on Pellets as a Dosage Form in Pharmaceuticals

Oral route of administration is widely accepted and desired because of its versatility, convenience, and, most importantly, patient compliance. Multiparticulate systems like granules and pellets are more advantageous when compared to single-unit dosage forms, as they are capable of distributing the drug more evenly in the gastrointestinal tract. The current paper focuses on pellets, the merits and demerits associated, various pelletization techniques, and their characterization. It also focuses on how pellets can be employed for drug delivery is controlled and sustained release formulations. It gives a complete emphasis on the drug and excipients that can be used in pellet formation, the marketed formulations, and the research pertaining to pellets.

Multicomponent ionic crystals of diltiazem with dicarboxylic acids toward understanding the structural aspects driving the drug-release

Diltiazem (DIL) is a calcium channel blocker antihypertensive drug commonly used in the treatment of cardiovascular disorders. Due to the high solubility and prompt dissolution of the commercial form hydrochloride (DIL-HCl) that is closely related to short elimination drug half-life, this API is known for exhibiting an unfitted pharmacokinetic profile. In an attempt to understand how engineered multicomponent ionic crystals of DIL with dicarboxylic acids can minimize these undesirable biopharmaceutical attributes, herein, we have focused on the development of less soluble and slower dissolving salt/cocrystal forms. By the traditional solvent evaporation method, two hydrated salts of DIL with succinic and oxalic acids (DIL-SUC-H₂O and DIL-OXA-H₂O), and one salt-cocrystal with fumaric acid (DIL-FUM-H₂FUM) were successfully prepared. An in-depth crystallographic description of these new solid forms was conducted through single and powder X-ray diffraction (SCXRD, PXRD), Hirshfeld surface (HS) analysis, energy framework (EF) calculations, Fourier Transform Infrared (FT-IR) spectroscopy, and thermal analysis (TG, DSC, and HSM). Structurally, the inclusion of dicarboxylic acids in the crystal structures provided the formation of 2D-sheet assemblies, where ionic pairs (DIL⁺/anion^-) are associated with each other via H-bonding. Consequently, a substantial lowering in both solubility (16.5-fold) and intrinsic dissolution rate (13.7-fold) of the API has been achieved compared to that of the hydrochloride salt. These findings demonstrate the enormous potential of these solid forms in preparing of novel modified-release pharmaceutical formulations of DIL.

Development of arsenic trioxide sustained-release pellets for reducing toxicity and improving compliance

Arsenic trioxide (ATO) is first-line drug for acute promyelocytic leukemia. Clinically, the continuously slow intravenous infusion is adopted to maintain effective blood concentration and reduce toxic effects, but it causes poor patient' compliance for a considerable infusion period. To overcome these disadvantages, we developed an oral ATO sustained-release preparation which was constructed via the ATO core pellets prepared by extrusion spheronization and followed by a coating membrane by fluid-bed technology. The prepared coated pellets displayed a round surface and uniform particle size. All in vitro release profiles of ATO pellets in different pH media and rotation speeds had no statistical difference. Importantly, the coated pellets can release completely in 12 h without obvious burst release. There was no distinct change in appearance and release behaviors in stability experiments. In vivo pharmacokinetics was studied by one-time intragastric administration of rats. Compared with free drug, the AUC_0-∞ of the ATO coated pellets was 2.3-fold higher, indicating the oral bioavailability was significantly increased. C_max decreased by about a half and T_max extended about 15 h. In particularly, the ATO level at 96 h only decreased about 20% of C_max , suggesting that the ATO sustained-release preparation could not only decrease the peak concentration, but also maintain a relatively constant blood concentration for a long period. Further, the in vivo absorption could be well predicted by in vitro release experiments. Therefore, the ATO sustained-release preparation formulated by the mature preparation technology, possessing satisfactory stability and improving bioavailability, had great application potentials for industrialization.

QbD based Eudragit coated Meclizine HCl immediate and extended release multiparticulates: formulation, characterization and pharmacokinetic evaluation using HPLC-Fluorescence detection method

This study is based on the QbD development of extended-release (ER) extruded-spheronized pellets of Meclizine HCl and its comparative pharmacokinetic evaluation with immediate-release (IR) pellets. HPLC-fluorescence method was developed and validated for plasma drug analysis. IR drug cores were prepared from lactose, MCC, and PVP using water as granulating fluid. Three-level, three-factor CCRD was applied for modeling and optimization to study the influence of Eudragit (RL100-RS100), TEC, and talc on drug release and sphericity of coated pellets. HPLC-fluorescence method was sensitive with LLOQ 1 ng/ml and linearity between 10 and 200 ng/ml with R² > 0.999. Pharmacokinetic parameters were obtained by non-compartmental analysis and results were statistically compared using logarithmically transformed data, where p > 0.05 was considered as non-significant with a 90% CI limit of 0.8-1.25. The AUC_0-t and AUC_0-∞ of ER pellets were not significantly different with geometric mean ratio 1.0096 and 1.0093, respectively. The C_max of IR pellets (98.051 ng/ml) was higher than the ER pellets (84.052 ng/ml) and the T_max of ER pellets (5.116 h) was higher than the IR pellets (3.029 h). No significant food effect was observed on key pharmacokinetic parameters of ER pellets. Eudragit RL100 (6%) coated Meclizine HCl pellets have a potential therapeutic effect for an extended time period.

Design of taste masked enteric orodispersible tablets of diclofenac sodium by applying fluid bed coating technology

Diclofenac sodium (DS) a non-steroidal anti-inflammatory drug has a bitter taste and is a local stomach irritant. The aim of this study was to formulate taste masked DS orally dispersible tablets (ODTs) with targeted drug release in the intestine. Pellets of DS were designed using sugar sphere cores layered with DS followed by an enteric coat of Eudragit L100 and a second coat of Eudragit E100 for taste masking. The produced pellets had a high loading efficiency of 99.52% with diameters ranging from 493.7 to 638.9 µm. The prepared pellets were spherical with smooth surfaces on scanning electron microscopy examination. Pellets with the 12% enteric coat Eudragit L100 followed by 5% Eudragit E 100 resulted in 1.4 ± 0.5% DS release in simulated gastric fluid (SGF) and complete dissolution in simulated intestinal fluid (SIF). The pellets were then used to formulate ODTs. In vitro disintegration time of ODTs ranged from 20 ± 0.26 to 46 ± 0.27 s in simulated saliva fluid (SSF). Dissolution was less than 10% in SGF while complete drug release occurred in SIF. The release rate was higher for the optimized formulation (F12) in SIF than for the marketed product Voltaren® 25 mg tablets. The optimized ODTs formulation had a palatable highly acceptable taste.

Crystal structures and physicochemical properties of diltiazem base and its acetylsalicylate, nicotinate and l-malate salts

Molecular salts of diltiazem with aspirin, niacin and l-malic acid have been synthesized. Their crystal structures and physicochemical properties have been investigated.