Preparation and in vitro evaluation of sustained release tablet formulations of diclofenac sodium

Development of Diclofenac Sodium 3D Printed Cylindrical and Tubular-Shaped Tablets through Hot Melt Extrusion and Fused Deposition Modelling Techniques

The present study aimed to develop 3D printed dosage forms, using custom-made filaments loaded with diclofenac sodium (DS). The printed tablets were developed by implementing a quality by design (QbD) approach. Filaments with adequate FDM 3D printing characteristics were produced via hot melt extrusion (HME). Their formulation included DS as active substance, polyvinyl alcohol (PVA) as a polymer, different types of plasticisers (mannitol, erythritol, isomalt, maltodextrin and PEG) and superdisintegrants (crospovidone and croscarmellose sodium). The physicochemical and mechanical properties of the extruded filaments were investigated through differential scanning calorimetry (DSC), X-ray diffraction (XRD) and tensile measurements. In addition, cylindrical-shaped and tubular-shaped 3D dosage forms were printed, and their dissolution behaviour was assessed via various drug release kinetic models. DSC and XRD results demonstrated the amorphous dispersion of DS into the polymeric filaments. Moreover, the 3D printed tablets, regardless of their composition, exhibited a DS release of nearly 90% after 45 min at pH 6.8, while their release behaviour was effectively described by the Korsmeyer-Peppas model. Notably, the novel tube design, which was anticipated to increase the drug release rate, proved the opposite based on the in vitro dissolution study results. Additionally, the use of crospovidone increased DS release rate, whereas croscarmellose sodium decreased it.

Effect of polymer type on characteristics of buccal tablets using factorial design

A two factor three level factorial design was used to investigate the effects of carbopol and cationic hydrophilic polymers which have a common use in buccal drug formulations. Statistical models with interaction terms were derived to evaluate influence of carbopol (X1) and chitosan (X2) on tablet disintegration (Y1) and dissolution (Y2), mechanical properties (Y3), swelling (Y4). Tablet disintegration studies were carried out using two different pH environments within buccal region pH limits and also two different commonly used dissolution methods for buccal tablets were also investigated to compare the effect of polymer type on dissolution. Polymer type and ratio affect the characteristics of the buccal tablets due to their different physicochemical behavior at buccal pH. Also significant variances between dissolution profiles for buccal tablets, using either USP Paddle or flow through cell methods were found. These results indicate that both polymer type and ratio as well as combination of them effects the drug behavior in different ways.

Prenatal exposure to low-dose diclofenac sodium does not affect total neuron numbers in spinal segment T13 in rats

The main purpose of the present study was to investigate the effects of diclofenac sodium (DS) on the total number of neurons in segment T13 of the spinal cord of offspring of pregnant rats using stereological methods. Eighteen adult female Wistar albino rats weighing 150-200g were used. Pregnant female rats were divided into three groups; a control group, a sham group and a DS (1mg/kg, intramuscular) exposed group. The DS and sham groups received injection from the 5th day of gestation to the 19th. Twenty eight days after birth, the offspring rats were perfused with 4% buffered formalin. T13, which is one of transverse spinal cord segments, were isolated and processed for routine paraffin histology. 5μm sections were obtained using a rotary microtome according to systematic random sampling strategies. Every 40th section was taken and sections were stained with modified Giemsa. All types of motor neuron cell were identified according to their morphology. In this study, the "disector-Cavalieri combination" method was used in the stereological examination of neurons. The motor neurons were counted in the right gray matter of the ventral horn in the spinal cord segment. The Kruskal-Wallis test was used for comparison the groups. In terms of motoneuron number, no significant difference among the groups was found (p>0.05). In conclusion, our results indicated that prenatal exposure to DS has no effect on the total number of motor neuron of the offspring rats.

Gastroretentive behavior of orally administered radiolabeled tamarind seed formulations in rabbits validated by gamma scintigraphy

This study aimed to formulate floating gastroretentive tablets containing metformin hydrochloric acid (HCl), using various grades of hydrogel such as tamarind powders and xanthan to overcome short gastric residence time of the conventional dosage forms. Different concentrations of the hydrogels were tested to determine the formulation that could provide a sustained release of 12 h. Eleven formulations with different ratios of tamarind seed powder/tamarind kernel powder (TKP):xanthan were prepared. The physical parameters were observed, and in vitro drug-release studies of the prepared formulations were carried out. Optimal formulation was assessed for physicochemical properties, thermal stability, and chemical interaction followed by in vivo gamma scintigraphy study. MKP3 formulation with a TKP:xanthan ratio of 3:2 was found to have 99.87% release over 12 h. Furthermore, in vivo gamma scintigraphy study was carried out for the optimized formulation in healthy New Zealand White rabbits, and the pharmacokinetic parameters of developed formulations were obtained. 153Sm2O3 was used to trace the profile of release in the gastrointestinal tract of the rabbits, and the drug release was analyzed. The time (Tmax) at which the maximum concentration of metformin HCl in the blood (Cmax) was observed, and it was extended four times for the gastroretentive formulation in comparison with the formulation without polymers. Cmax and the half-life were found to be within an acceptable range. It is therefore concluded that MKP3 is the optimal formulation for sustained release of metformin HCl over a period of 12 h as a result of its floating properties in the gastric region.

Use of hydrophilic and hydrophobic polymers for the development of controlled release tizanidine matrix tablets

The aim of the present study was to develop tizanidine controlled release matrix. Formulations were designed using central composite method with the help of design expert version 7.0 software. Avicel pH 101 in the range of 14-50% was used as a filler, while HPMC K4M and K100M in the range of 25-55%, Ethylcellulose 10 ST and 10FP in the range of 15 - 45% and Kollidon SR in the range of 25-60% were used as controlled release agents in designing different formulations. Various physical parameters including powder flow for blends and weight variation, thickness, hardness, friability, disintegration time and in-vitro release were tested for tablets. Assay of tablets were also performed as specified in USP 35 NF 32. Physical parameters of both powder blend and compressed tablets such as compressibility index, angle of repose, weight variation, thickness, hardness, friability, disintegration time and assay were evaluated and found to be satisfactory for formulations K4M2, K4M3, K4M9, K100M2, K100M3, K100M9, E10FP2, E10FP9, KSR2, KSR3 & KSR9. In vitro dissolution study was conducted in 900 ml of 0.1N HCl, phosphate buffer pH 4.5 and 6.8 medium using USP Apparatus II. In vitro release profiles indicated that formulations prepared with Ethocel 10 standard were unable to control the release of drug while formulations K4M2, K100M9, E10FP2 & KSR2 having polymer content ranging from 40-55% showed a controlled drug release pattern in the above mentioned medium. Zero-order drug release kinetics was observed for formulations K4M2, K100M9, E10FP2 & KSR2. Similarity test (f2) results for K4M2, E10FP2 & KSR2 were found to be comparable with reference formulation K100M9. Response Surface plots were also prepared for evaluating the effect of independent variable on the responses. Stability study was performed as per ICH guidelines and the calculated shelf life was 24-30 months for formulation K4M2, K100M9 and E10FP2.

Isolation, characterization, and evaluation of Cassia fistula Linn. seed and pulp polymer for pharmaceutical application

Introduction:

Present work, is an effort toward exploring the potential of Cassia fistula Linn. seed gum as an extended release polymer and laxative. While, C. fistula pulp polymer has evaluated as suspending agent.

Materials and Methods:

For extended release application, total five batches (F1-F5) were prepared by varying the ratio of drug:polymer as 1:1, 1:2, 1:3, 1:4, and 1:5, respectively. The granules were prepared by wet granulation method and further evaluated for micromeritic properties such as angle of repose (θ), Carr's compressibility index (CCI), and Hausner's ratio. Further compacts were evaluated by hardness, thickness, swelling index, in-vitro dissolution, and so on. Laxative activity was evaluated by administration of seed polymer (100 mg/kg) alone or in combination with bisacodyl (2.5 mg/kg) in 1% Tween 80. Zinc oxide suspension was prepared by varying the concentration of C. fistula pulp polymer and compared with suspension made by use of tragacanth, sodium carboxymethyl cellulose and bentonite.

Results:

Result showed that granules were free flowing, while the compact extended the drug release up to 10 h (72.84 ± 0.98; batch F5) and followed Higuchi matrix release kinetics. This extended release might be due to the formation of polyelectrolyte complex because of gluco-mannose in seed gum. Result of in-vivo laxative activity showed that seed polymer reduced faeces weight after 24 h compared to control (P < 0.01).

Conclusions:

Pulp polymer showed good sedimentation volume, but alone fails to stabilize the suspension for a longer period, so it could be useful in combination with other suspending agents and can be useful as novel excipient.

Preparation and characterization of a gastric floating dosage form of capecitabine

Gastrointestinal disturbances, such as nausea and vomiting, are considered amongst the main adverse effects associated with oral anticancer drugs due to their fast release in the gastrointestinal tract (GIT). Sustained release formulations with proper release profiles can overcome some side effects of conventional formulations. The current study was designed to prepare sustained release tablets of Capecitabine, which is approved by the Food and Drug Administration (FDA) for the treatment of advanced breast cancer, using hydroxypropyl methylcellulose (HPMC), carbomer934P, sodium alginate, and sodium bicarbonate. Tablets were prepared using the wet granulation method and characterized such that floating lag time, total floating time, hardness, friability, drug content, weight uniformity, and in vitro drug release were investigated. The sustained release tablets showed good hardness and passed the friability test. The tablets' floating lag time was determined to be 30-200 seconds, and it floated more than 24 hours and released the drug for 24 hours. Then, the stability test was done and compared with the initial samples. In conclusion, by adjusting the right ratios of the excipients including release-retarding gel-forming polymers like HPMC K4M, Na alginate, carbomer934P, and sodium bicarbonate, sustained release Capecitabine floating tablet was formulated.

The differences between the branded and generic medicines using solid dosage forms: In-vitro dissolution testing

INTRODUCTION

Dissolution is the amount of substance that goes into solution per unit time under standardised conditions of liquid/solid interface, solvent composition and temperature. Dissolution is one of the most important tools to predict the in-vivo bioavailability and in some cases to determine bioequivalence and assure interchangeability.

AIM

To compare the differences in dissolution behaviour of solid dosage forms between innovators (reference products) and their generic counterparts (tested products).

METHODS

Four replicates for each batch of 37 tested medicines was carried out using A PT-DT70 dissolution tester from Pharma Test. A total of 13 branded medicines and 24 generic counterparts were obtained locally and internationally to detect any differences in their dissolution behaviour. They were tested according to the British Pharmacopeia, European Pharmacopeia and the US Pharmacopeia with the rate of dissolution determined by ultra-violet Spectrophotometery.

RESULTS

Most tested medicines complied with the pharmacopoeial specifications and achieved 85% dissolution in 60 min. However, some generic medicines showed significant differences in dissolution rate at 60 and 120 min. Many generic medicines showed a slower dissolution rate than their branded counterparts such as the generic forms of omeprazole 20 mg. Some showed an incomplete dissolution such as the generic form of nifedipine 10 mg. Other generics showed faster dissolution rate than their branded counterpart such as the generic forms of meloxicam 15 mg. Moreover, some generics from different batches of the same manufacturer showed significant differences in their dissolution rate such as the generic forms of meloxicam 7.5 mg. Nevertheless, some generic medicines violated the EMA and the FDA guidelines for industry when they failed to achieve 85% dissolution at 60 min, such as the generic form of diclofenac sodium 50 mg.

CONCLUSION

Most medicines in this study complied with the pharmacopeial limits. However, some generics dissolved differently than their branded counterparts. This can clearly question the interchangeability between the branded and its generic counterpart or even among generics.

Oxycellulose beads with drug exhibiting pH-dependent solubility

The aim of this study was to develop novel hydrogel-based beads and characterize their potential to deliver and release a drug exhibiting pH-dependent solubility into distal parts of gastrointestinal (GI) tract. Oxycellulose beads containing diclofenac sodium as a model drug were prepared by the ionotropic external gelation technique using calcium chloride solution as the cross-linking medium. Resulting beads were characterized in terms of particle shape and size, encapsulation efficacy, swelling ability and in vitro drug release. Also, potential drug-polymer interactions were evaluated using Fourier transform infrared spectroscopy. The particle size was found to be 0.92-0.96 mm for inactive (oxycellulose only) and 1.47-1.60 mm for active (oxycellulose-diclofenac sodium) beads, respectively. In all cases, the sphericity factor was between 0.70 and 0.81 with higher values observed for samples containing higher polymer and drug concentrations. The swelling of inactive beads was found to be strongly influenced by the pH and composition (i.e. Na(+) concentration) of the selected media (simulated gastric fluid vs. phosphate buffer pH 6.8). The encapsulation efficiency of the prepared particles ranged from 58% to 65%. Results of dissolution tests showed that the drug loading inside of the particles influenced the rate of its release. In general, prepared particles were able to release the drug within 12-16 h after a lag time of 4 h. Fickian diffusion was found as the predominant drug release mechanism. Thus, this novel particulate system showed a good potential to deliver drugs specifically to the distal parts of the human GI tract.

Evaluation of mucilage of Hibiscus rosasinensis Linn as rate controlling matrix for sustained release of diclofenac

This article reports the exploitation of novel hydrophilic excipient, that is, mucilage from Hibiscus rosasinensis Linn, for the development of sustained release tablet. Swelling ratio and flow properties analyses of dried mucilage powder were carried out. A 3(2) full factorial design was used. In factorial design, amounts of dried mucilage and dibasic calcium phosphate (DCP) were taken as independent factors and percentage drug release in 60 and 300 min and time for 80% drug release as dependent variables. Matrix tablet containing dried mucilage and diclofenac sodium (DS) was prepared through direct compression techniques. DS tablets were evaluated for hardness, friability, weight variation, in vitro drug release and water uptake, and mass loss study. The dried mucilage powder shows superior swelling capacity and excellent flow properties. Prepared tablets have acceptable hardness, friability, and uniformity in weight. It was found that batch HD8 fulfills all selected criteria. Drug release kinetics from these formulations corresponded best to the zero-order kinetics. Water uptake was independent whereas mass loss was dependent on agitation speed. The concept of similarity factor (f(2)) was used to prove similarity of dissolution profile in distilled water and phosphate buffer and was found to be 90.68. It was concluded that mucilage can be used as release-retarding agent for 12 h when the drug-mucilage ratio was 1:1.5. So, matrix tablet containing dried mucilage is most suitable for sustained release of DS.

Liquisolid technique as a new approach to sustain propranolol hydrochloride release from tablet matrices

It is suggested here that liquisolid technique has the potential to be optimized for the reduction of drug dissolution rate and thereby production of sustained release systems. In the present study, propranolol hydrochloride was dispersed in polysorbate 80 as the liquid vehicle. Then a binary mixture of carrier-coating materials (Eudragit RL or RS as the carrier and silica as the coating material) was added to the liquid medication under continuous mixing in a mortar. The final mixture was compressed using the manual tableting machine. The effect of drug concentration, loading factor, thermal treating and aging on release profile of propranolol hydrochloride from liquisolid compacts were investigated at two pH values (1.2 and 6.8). The release rate of propranolol HCl from liquisolid compacts was compared to the release of propranolol HCl from conventional tablets. X-ray crystallography and DSC were used to investigate the formation of any complex between drug and excipients or any crystallinity changes during the manufacturing process. Propranolol HCl tablets prepared by liquisolid technique showed greater retardation properties in comparison with conventional matrix tablets. This investigation provided evidence that polysorbate 80 (Tween 80) has important role in sustaining the release of drug from liquisolid matrices, and a reduction of T(g) of the polymer can be the reason for the release prolongation of liquisolid tablets. The results also showed that wet granulation had remarkable impact on release rate of propranolol HCl from liquisolid compacts, reducing the release rate of drug from liquisolid compacts. The results showed that aging (liquisolid tablets were kept at 25 degrees C/75% relative humidity for 6 months) had no effect on hardness and dissolution profile of drug. The kinetics studies revealed that most of the liquisolid formulations followed the zero-order release pattern. X-ray crystallography and DSC ruled out any changes in crystallinity or complex formation during the manufacturing process of liquisolid formulations.

Effect of prenatal exposure to diclofenac sodium on Purkinje cell numbers in rat cerebellum: A stereological study

Diclofenac sodium (DS) is commonly used as a non-steroidal anti-inflammatory drug. Although several adverse effects are clearly established, it is still unknown whether prenatal exposure to DS has an effect on the development of the cerebellum. In this study, we investigated the total number of Purkinje cells of the cerebellum in a control group and in a DS-treated group of male rats using a stereological method. The DS in a dose of 1 mg/kg daily was intraperitoneally injected to the drug-treated group of pregnant rats beginning from the 5th day after mating for a period of 15 days during pregnancy. Physiological serum at 1 ml dose was intraperitoneally injected to the control group of pregnant rats at the same period. After delivery, male offspring were obtained and each main group was divided into two subgroups that were 4-week-old (4W-old) and 20-week-old (20W-old). Our results showed that the total number of Purkinje cells in offspring of drug-treated rats was significantly lower than in the offspring of control animals. These results suggest that the Purkinje cells of a developing cerebellum may be affected by administration of DS during the prenatal period.