Release Of Betamethasone Research Articles

Biphasic release of betamethasone from an injectable HA hydrogel implant for alleviating lumbar disc herniation induced sciatica

Epidural steroid injection (ESI) is a common therapeutic approach for managing sciatica caused by lumbar disc herniation (LDH). However, the short duration of therapeutic efficacy and the need for repeated injections pose challenges in LDH treatment. The development of a controlled delivery system capable of prolonging the effectiveness of ESI and reducing the frequency of injections, is highly significant in LDH clinical practice. In this study, we utilized a thiol-ene click chemistry to create a series of injectable hyaluronic acid (HA) based release systems loaded with diphasic betamethasone, including betamethasone dipropionate (BD) and betamethasone 21-phosphate disodium (BP) (BD/BP@HA). BD/BP@HA hydrogel implants demonstrated biocompatibility and biodegradability to matched neuronal tissues, avoiding artificial compression following injection. The sustained release of betamethasone from BD/BP@HA hydrogels effectively inhibited both acute and chronic neuroinflammation by suppressing the nuclear factor kappa-B (NF-κB) pathway. In a mouse model of LDH, the epidural administration of BD/BP@HA efficiently alleviated LDH-induced sciatica for at least 10 days by inhibiting the activation of macrophages and microglia in dorsal root ganglion and spinal dorsal horn, respectively. The newly developed HA hydrogels represent a valuable platform for achieving sustained drug release. Additionally, we provide a simple paradigm for fabricating BD/BP@HA for epidural injection, demonstrating greater and sustained efficiency in alleviating LDH-induced sciatica compared to traditional ESI and displaying potentials for clinical translation. This system has the potential to revolutionize drug delivery for co-delivery of both soluble and insoluble drugs, thereby making a significant impact in the pharmaceutical industry. Statement of SignificanceLumbar disc herniation (LDH) is a common degenerative disorder leading to sciatica and spine surgery. Although epidural steroid injection (ESI) is routinely used to alleviate sciatica, the efficacy is short and repeated injections are required. There remains challenging to prolong the efficacy of ESI. Herein, an injectable hyaluronic acid (HA) hydrogel implant by crosslinking acrylated-modified HA (HA-A) with thiol-modified HA (HA-SH) was designed to achieve a biphasic release of betamethasone. The hydrogel showed biocompatibility and biodegradability to match neuronal tissues. Notably, compared to traditional ESI, the hydrogel better alleviated sciatica in vivo by synergistically inhibiting the neuroinflammation in central and peripheral nervous systems. We anticipate the injectable HA hydrogel implant has the potential for clinical translation in treating LDH-induced sciatica.

Synthesis and Evaluation of AlgNa-g-Poly(QCL-co-HEMA) Hydrogels as Platform for Chondrocyte Proliferation and Controlled Release of Betamethasone.

Hydrogels obtained from combining different polymers are an interesting strategy for developing controlled release system platforms and tissue engineering scaffolds. In this study, the applicability of sodium alginate-g-(QCL-co-HEMA) hydrogels for these biomedical applications was evaluated. Hydrogels were synthesized by free-radical polymerization using a different concentration of the components. The hydrogels were characterized by Fourier transform-infrared spectroscopy, scanning electron microscopy, and a swelling degree. Betamethasone release as well as the in vitro cytocompatibility with chondrocytes and fibroblast cells were also evaluated. Scanning electron microscopy confirmed the porous surface morphology of the hydrogels in all cases. The swelling percent was determined at a different pH and was observed to be pH-sensitive. The controlled release behavior of betamethasone from the matrices was investigated in PBS media (pH = 7.4) and the drug was released in a controlled manner for up to 8 h. Human chondrocytes and fibroblasts were cultured on the hydrogels. The MTS assay showed that almost all hydrogels are cytocompatibles and an increase of proliferation in both cell types after one week of incubation was observed by the Live/Dead® assay. These results demonstrate that these hydrogels are attractive materials for pharmaceutical and biomedical applications due to their characteristics, their release kinetics, and biocompatibility.

Enzymatically crosslinked tyramine-gellan gum hydrogels as drug delivery system for rheumatoid arthritis treatment.

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by joint synovial inflammation, as well as cartilage and bone tissue destruction. Current strategies for the treatment of RA can reduce joint inflammation, but the treatment options still represent stability concerns since they are not sufficient and present a fast clearing. Thus, several drug delivery systems (DDS) have been advanced to tackle this limitation. Injectable gellan gum (GG) hydrogels, reduced by physical crosslinking methods, also being proposed as DDS, but this kind of crosslinking can produce hydrogels that become weaker in physiological conditions. Nevertheless, enzymatic crosslinking emerged as an alternative to increase mechanical strength, which can be adjusted by the degree of enzymatic crosslinking. In this study, tyramine-modified gellan gum (Ty-GG) hydrogels were developed via horseradish peroxidase (HRP) crosslinking; and betamethasone was encapsulated within, to increase the specificity and safety in the treatment of patients with RA. Physicochemical results showed that it was possible to modify GG with tyramine, with a degree of substitution of approximately 30%. They showed high mechanical strength and resistance, presenting a controlled betamethasone release profile over time. Ty-GG hydrogels also exhibited no cytotoxic effects and do not negatively affected the metabolic activity and proliferation of chondrogenic primary cells. Furthermore, the main goal was achieved since betamethasone-loaded Ty-GG hydrogels demonstrated to have a more effective therapeutic effect when compared with the administration of betamethasone alone. Therefore, the developed Ty-GG hydrogels represent a promising DDS and a reliable alternative to traditional treatments in patients with RA.

Inulin-Grafted Stearate (In-g-St) as the Effective Self-Assembling Polymeric Micelle: Synthesis and Evaluation for the Delivery of Betamethasone

Background. Betamethasone as a corticosteroid drug is commonly used for the treatment of rheumatoid arthritis. Unfortunately, betamethasone is a low water-soluble drug and its efficacy is low. So an attractive strategy is the targeted delivery of betamethasone to the damaged joint using polymeric micelle-based carriers. Methods. Inulin-grafted stearate (In-g-St) was synthesized via the reaction of stearoyl chloride and inulin, then characterized by FT-IR and H-NMR. In-g-St forms micelles in the presence of betamethasone. The prepared polymeric micelles were characterized for size, zeta potential, drug loading, particles’ morphology, critical micelle concentration (CMC), and encapsulation efficiency. So sustained release polymeric micelles of betamethasone were developed by employing In-g-St. Results. The measurement of particle size showed a mean diameter of 60 and 130 nm for 10% and 20% drug-loaded micelles, respectively, and SEM showed that the particle’s morphologies are spherical. Zeta potential measurement for the drug-containing micelles showed a value of -11.8 mV. Drug loading efficiency and the encapsulation efficiency were 6.36% and 63.6%, as well as 18.97% and 94.88% for 10% and 20%, respectively. 20% drug-loaded polymer showed a small burst release of betamethasone at the first 3 h which was followed by sustained release in the next 24 h. Furthermore, the formula with 10% exhibited good sustained release properties except for the minor initial burst release. Conclusion. Data from the zeta potential, CMC, drug loading capacity, and in vitro drug release studies indicated that In-g-St polymeric micelles can be suitable candidates for the efficient delivery of hydrophobic drugs like betamethasone.

Evaluation of the Release Kinetics of a Pharmacologically Active Substance from Model Intra-Articular Implants Replacing the Cruciate Ligaments of the Knee.

Implants are readily applied as a convenient method of therapy. There is great interest in the prolonged release of active substances from implants. The objective of this work was to evaluate the dissolution kinetics of steroidal anti-inflammatory preparation (SAP) released from novel implants, and to test the influence of the technology on SAP release kinetics. The proposed long-acting preparations may overcome difficulties resulting from repeated injections and often visits to ambulatory clinic, as the stabilizing function of the artificial ligament would be enriched with pharmacological activity. The potential advantages provided by the new coatings of knee implants include the continuous, sustained, and prolonged release of an active substance. The study was carried out using a modified United States Pharmacopoeia (USP) apparatus 4. The amount of SAP was measured spectroscopically. It was revealed that the transport of the drug was mainly a diffusion process. The drug release kinetics was analyzed using zero-, first-, and second-order kinetics as well as Korsmeyer-Peppas, Higuchi, and Hixon-Crowell models. The highest values of the release rate constants were k0 = (7.49 ± 0.05) × 10−5 mg × min−1, k1 = (6.93 ± 0.05) × 10−6 min−1, and k2 = (7.70 ± 0.05) × 10−7 mg−1 × min−1 as calculated according to zero-, first-, and second-order kinetics equations, respectively. The values of the rate constants obtained for the slowest process were k0 = (3.63 ± 0.06) × 10−5 mg × min−1, k1 = (2.50 ± 0.03) × 10−6 min−1, and k2 = (2.80 ± 0.03) × 10−7 mg−1 × min−1. They may suggest the possibility of sustained release of betamethasone from the system. Due to the statistical analysis, differences were observed between most of the studied implants. Incubation, temperature, time of stabilization of layers, and the method of SAP deposition on the matrix affected the drug release.

Controlled and sustained release of a corticosteroid drug from block copolymers synthetized by ATRP

During last decades, implantable drug delivery systems (DDS) have been developed to optimize therapeutic properties of drugs and ensure their release in a specific site. Acrylic polymers have obtained growing interest in biomedical applications for their biocompatibility and chemical properties that make them extremely versatile. In this work, we focused on the realization of polymeric systems for controlled and sustained release of betamethasone 17,21‐dipropionate (BDP), a corticosteroid drug, in the treatment of the posterior eye diseases (PED). The investigated DDS were made of opportunely designed methacrylic block copolymers. Different series of methylmethacrylate/2‐hydroxyethylmethacrylate (MMA/HEMA) block copolymers, with various monomeric compositions (20‐60 mol% HEMA), were synthetized by Atom Transfer Radical Polymerization to find the best hydrophilic/hydrophobic ratio, able to ensure optimal kinetic release. Copolymers were characterized by nuclear magnectic resonance, size exclusion chromatography, and differential scanning calorimetry. Monitoring of drug release from films loaded with BDP was carried out by HPLC analysis. In particular, PMMA‐b‐PHEMA with 47 mol% of HEMA showed the best release profile to achieve the therapeutic reference dose, used in the treatment of PED (1‐3 µg/day), up to four months. Additionally, intraocular inserts with different shapes were prepared using silicon molds made by means of a 3D printer. POLYM. ENG. SCI., 57:570–578, 2017. © 2017 Society of Plastics Engineers

Simultaneously Load and Extended Release of Betamethasone and Ciprofloxacin from Vitamin E-Loaded Silicone-Based Soft Contact Lenses

ABSTRACTPurpose: The purpose of the present study was to evaluate the efficacy of commercial soft contact lenses, loaded with vitamin E, as ocular drug delivery systems for simultaneous loading and release of ciprofloxacin (Cipro) and betamethasone (BMZ) in artificial tears.Methods: In this study, we applied vitamin E as a barrier to increase BMZ-Cipro loading into three commercial silicone-based soft contact lenses and control their simultaneous release into the artificial lachrymal fluid. Two different concentrations of vitamin E solution (0.1 and 0.2 g/ml) were used, and various parameters including changes in lens diameter, water content, ultraviolet-visible light (UV-Vis) transmittance, drug-binding properties, and drug release profile were investigated.Results: The obtained results indicated that vitamin E significantly reduced the swelling properties of contact lenses in aqueous media, while it enhanced the lens diameter in both dry and hydrated states. Vitamin E had no significant effects on visible transmittance, while it blocked UV radiation, which could be harmful for the eye surface. Our findings revealed that vitamin E improved the simultaneous loading amount of BMZ-Cipro into soft contact lenses. Additionally, BMZ and Cipro release rates significantly reduced after using vitamin E as a hydrophobic diffusion barrier. After soaking the lenses in 0.1 and 0.2 g/ml of vitamin E solution, BMZ release time increased by 28.8–81.6 and 182.4–201 folds, respectively. Moreover, Cipro release time increased by 12–18 and 1152–2313 folds, respectively.Conclusion: The results of the present study indicated the efficacy of vitamin E as a diffusion barrier in developing a controlled drug delivery system for the simultaneous loading of BMZ and Cipro and sustaining their release from soft contact lenses.

Controlled release of betamethasone from vitamin E-loaded silicone-based soft contact lenses

Context: Betamethasone (BMZ) is an effective drug which is commonly used as an eye drop for the management of ophthalmic inflammations. Due to low ocular bioavailability, it is necessary to prepare and optimize an ocular drug delivery system for BMZ.Objective: In this study we tried to use vitamin E diffusion barrier for sustaining BMZ release.Materials and methods: Three commercial contact lenses were soaked in vitamin E solutions and swelling percentage, diameter, transmittance, binding capacity and release amount and time were evaluated in comparison with non-vitamin E-loaded pure lenses.Results: The results showed that vitamin E significantly decreased water content of contact lenses whereas, increased the lens diameter in both dry and wet states. It effectively blocked UV radiation which is harmful for the eye surface while had no significant effect on visible transmittance. BMZ loading capacity enhanced and release rate remarkably decreased after using vitamin E as a hydrophobic diffusion barrier.Discussion and conclusions: This study revealed that vitamin E can be applied as a hydrophobic diffusion barrier for controlling and sustaining BMZ release from silicone-based soft contact lenses into the lachrymal fluid. It can also protect eye tissues as an antioxidant by blocking the UV radiation.

Synthesis and characterization of the core ‐shell magnetic molecularly imprinted polymer nanoparticles using 2‐(methacrylamido)ethyl methacrylate amide as a novel cross‐link agent for controlled release of betamethasone

Synthesis and characterization of the core ‐shell magnetic molecularly imprinted polymer nanoparticles using 2‐(methacrylamido)ethyl methacrylate amide as a novel cross‐link agent for controlled release of betamethasone

Retracted: Synthesis and characterization of the core–shell magnetic molecularly imprinted polymer nanoparticles using 2‐(methacrylamido)ethyl methacrylate amide as a novel crosslink agent for controlled release of betamethasone

AbstractThe following article from the Journal of Applied Polymer Science, “Synthesis and characterization of the core–shell magnetic molecularly imprinted polymer nanoparticles using 2‐(methacrylamido)ethyl methacrylate amide as a novel cross‐link agent for controlled release of betamethasone,” by Saman Azodi‐Deilami, Majid Abdouss, and Davood Kordestani, published online on 4 February 2014 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors, the journal's editors, and Wiley Periodicals, Inc. The retraction has been agreed because of significant, unacknowledged overlap with the author's previously published work (http://dx.doi.org/10.1007/s10856-013-5118-8). In addition, the crosslinker the authors call novel was first reported by a separate group of authors (http://dx.doi.org/10.1021/ja038961b), albeit this was not known by the authors of the retracted article at the time of publication.

Preparation of N,N-p-phenylene bismethacryl amide as a novel cross-link agent for synthesis and characterization of the core–shell magnetic molecularly imprinted polymer nanoparticles

Novel magnetic molecularly imprinted nanoparticles (MMIPs) using N,N-p-phenylene bismethacryl amide as a cross linker and super paramagnetic core-shell nanoparticle as a supporter for use in controlled release were prepared by precipitation polymerization. Novel cross-linking agents were synthesized by the reaction of methacryloyl chloride with p-phenylenediamine. Then, the Fe3O4 nanoparticles were encapsulated with a SiO2 shell and functionalized with -CH=CH2 and MMIPs were further prepared by using methacrylic acid as a functional monomer, N,N-p-phenylene bismethacryl amide as a cross-linking agent and betamethasone as template. Magnetic non-MIPs were also prepared with the same synthesis procedure as with MMIPs only without the presence of the template. The obtained MMIPs were characterized by using transmission electron microscopy, Fourier transform infrared spectrum, X-ray diffraction, energy-dispersive X-ray spectroscopy, and the vibrating sample magnetometer. The performance of the MMIPs for the controlled release of betamethasone was assessed and results indicated that the magnetic MIPs also had potential applications in drug controlled release.

Effect of Freezing and Thawing Process on Betamethasone Acetate Release from Polyvinyl Alcohol Nanospheres

Betamethasone acetate (BA) is a glucocorticoid steroid with anti-inflammatory and immunosuppressive properties which can be used in treatment of asthma and itching. In this research, polyvinyl alcohol nanospheres loaded by betamethasone acetate were prepared by oil in water emulsion method after which they were exposed to 1, 2 and 4 cycles of freeze-thawing (F-T) process including 24 hours freezing cycle at -25 °C and 24 hours thawing at ambient temperature. Nanospheres fabrication was confirmed by transmission electron microscopy and betamethasone release was analyzed by UV spectrophotometer at 245 nm. The results revealed that by increasing the number of F-T cycles the rate of drug release decreased. The effect of BA concentration was also investigated on human chondrosarcoma (sw 1353). The MTT assay was utilized to assess the cell proliferation. The results showed that these biocompatible nanospheres can be used for sustained release of such drugs for more than four months and drug release rate can be effectively controlled by implementing F-T cycles.

Investigation of Drug Release from Biodegradable Polymeric Delivery System by Infrared Spectrometry

This study investigates some effective parameters in betamethasone release from in situ forming biodegradable drug delivery systems. The drug delivery systems are based on two biodegradable polymers of poly(D,L-lactide-co-glycolide) (PLGA), which are commercially called RG504h and RG756. Temperature, polymer type, and γ-irradiation are the parameters investigated by attenuated total reflectance Fourier transform-infrared (ATR-FTIR) spectrometry in the 1891–1324 cm−1 spectral region. Obtained results were compared with those of the HPLC method, demonstrating several similarities. N-methyl-2-pyrrolidinone (NMP) was employed as solvent. The γ-radiation (25 kGy) has no effect on decomposition of betamethasone, while it increases the rate of drug release. RG756 reduces the release rate in comparison with RG504H. Temperature does not affect the amount of free drug in the polymer matrix. The partial least squares (PLS) regression method with path length constant, mean centering, and variance scaling techniques was applied. Correlation coefficient R2 and root mean square error of calibration (RMSEC) were 0.998 and 0.106 respectively.

In Vitro Evaluation of Drug Solubility and Gamma Irradiation on the Release of Betamethasone under Simulated In Vivo Conditions

In situ—forming biodegradable polymeric systems loaded with betamethasone (BTM) and betamethasone acetate (BTMA) (5, 7, and 10% (w/w)) were prepared using poly(DL-lactide-co-glycolide) (33% (w/w)), ethyl heptanoate (5% (w/w)), and N-methyl-2-pyrrolidone as biodegradable material, additive, and solvent, respectively. The effects of gamma irradiation, drug loading, and solvent removal on release profiles were evaluated. The drug release in phosphate-buffered solution (pH = 7.4, 37°C) was measured using high-performance liquid chromatography. The release profiles of irradiated and nonirradiated formulations based on BTMA showed a three-phase release pattern, whereas the pattern for BTM was biphasic. Gamma irradiation had no significant effect on the BTMA release profiles ( p>0.05). Unexpectedly, irradiation had a significant effect on release behavior of BTM ( p<0.05); also, the rate of BTM release was decreased with an increase in drug loading up to 10%. The amount of BTM that was released in the burst phase decreased by about 1.4 and 1.5 times for 7 and 10% BTM loading, respectively. The duration of BTM release was more than that of BTMA. Changes in hydrophobicity and hydrogen bonding had a strong effect on the release behavior of the two forms of BTM from the in situ—forming systems.

OCULAR TISSUE DISTRIBUTION OF BETAMETHASONE AFTER ANTERIOR-EPISCLERAL, POSTERIOR-EPISCLERAL, AND ANTERIOR-INTRASCLERAL PLACEMENT OF NONBIODEGRADABLE IMPLANTS

To investigate the intraocular distribution of betamethasone (BM) after implantation of transscleral drug delivery devices at three different sites in the eye: anterior episclera, posterior episclera, and anterior intrasclera. Nonbiodegradable implants designed to release BM for at least 1 month were placed at three different sites in albino rabbit eyes. The concentrations of BM in the aqueous humor, vitreous, and retina-choroid were determined by high-performance liquid chromatography at 4 weeks after placement. The distribution of BM in the retina-choroid was also evaluated. In the in vitro and in vivo release study, the release of BM from implants in vivo correlated comparatively with those in vitro in all studied devices. The concentrations of BM in ocular tissues were measured after the implantations. The concentrations of BM after anterior-intrascleral placement of the implants were highest in the vitreous and retina-choroid among the three sites. The concentrations of BM in the three different sections of retina-choroid, which were around the placement site, opposite the placement site and posterior pole, were also determined. The concentration of BM in the retina-choroid around the placement site was higher than that in other parts of the retina-choroid after anterior-episcleral and anterior-intrascleral placement of implants. The implants at the anterior-intrascleral site yielded the highest concentrations of BM in the anterior part and posterior pole of the retina-choroid among the three placement sites. Only the implant at the posterior-episcleral site showed a higher concentration of BM at the posterior pole of the retina-choroid than at the other anterior part. Transscleral drug delivery devices may be feasible systems to deliver BM to intraocular tissues. The placement site of the device should be selected according to the location of the targeted lesions.

Optimizing formulation factors in preparing chitosan microparticles by spray-drying method

The chitosan only, chitosan/Pluronic F68, chitosan/gelatin, chitosan/Pluronic F68/gelatin microparticles and betamethasone-loaded chitosan/Pluronic F68/ gelatin microparticles were successfully prepared by a spray-drying method. Microparticle characteristics (yield rate, zeta potential, particle size and tap density), loading efficiencies, microparticle morphology and in-vitro release properties were investigated. By properly choosing excipient type, concentration and varying the spray-drying parameters, a high degree of control was achieved over the physical properties of the dry chitosan powders. SEM micrograph shows that the particle sizes of the varied chitosan composed microparticles ranged from 2.12–5.67 μm and the external surfaces appeal-smooth. Using betamethasone as model drug, the spray-drying is a promising way to produce good spherical and smooth surface microparticles with a narrow particle size range for controlled delivery of betamethasone. The positively charged betamethasone-loaded microparticles entrapped in the chitosan/Pluronic F68/gelatin microparticles with trapping efficiencies up to 94.5%, yield rate 42.5% and mean particle size 5.64 μm varied between 4.32–6.20 μm and tap densities 0.128 g/cm3. The pH of particle was increased with increasing betamethasone-loaded amount, but both zeta potential and tap density of the particles decreased with increasing betamethasone-loaded amount. The betamethasone release rates from chitosan/Pluronic F68/gelatin microparticles were influenced by the drug/polymer ratio in the manner that an increase in the release% and burst release% was observed when the drug loading was decreased. The in vitro release of betamethasone showed a dose-dependent burst followed by a slower release phase that was proportional to the drug concentration in the concentration range between 14–44%w/w.

The characteristics of betamethasone-loaded chitosan microparticles by spray-drying method

Betamethasone (BTM)-loaded microparticles prepared by a spray drying method using chitosan (CTS) as raw material, type-A gelatin and ethylene oxide-propylene oxide block copolymer (Pluronic F68) as modifiers. The BTM-loaded in varied chitosan/Pluronic F68/gelatin microparticle formulations was investigated. By properly choosing excipient type and concentration a high degree of control was achieved over the physical properties of the BTM-loaded microparticles. Microparticle characteristics (zeta potential, tap density, particle size and yield), loading efficiencies, microparticle morphology and in-vitro release properties were examined. Surface morphological characteristics and surface charges of prepared microparticles were observed by using scanning electron microscopy (SEM) and microelectrophoresis. A SEM micrograph shows that the particle sizes of the varied chitosan composed microparticles ranged from 1.1-4.7 μ m and the external surfaces appear smooth. The BTM-loaded microparticles entrapped in the chitosan/Pluronic F68/gelatin microparticles with trapping efficiencies up to 93%, collected yield rate 44%, and mean particle size varied between 1-3 μ m, positive surface charge (20-40 mv), and tap densities (0.04-0.40 g/cm3) were obtained. The collected BTM yield and size of particle was increased with increasing BTM-loaded amount but both zeta potential and tap density of the particles decreased with increasing BTM-loaded amount. The in vitro release of BTM showed a dose-dependent burst followed by a slower release phase that was proportional to the drug concentration in the concentration range between 5-30%w/w. The in vitro drug release from the chitosan/Pluronic F68/gelatin 1/0.1/0.4 microspheres had a prolong release pattern. These formulation factors were correlated to particulate characteristics for optimizing BTM microspheres in pulmonary delivery.

Drug Release from a Suspension with a Finite Dissolution Rate: Theory and Its Application to a Betamethasone 17-Valerate Patch

A random walk method for a diffusion equation is applied to the model for a suspension with a finite dissolution rate developed by Ayres and Lindstrom in 1977. In the method, the diffusion of dissolved drug and dissolution of crystal are calculated separately using a simple BASIC program. The random walk method strictly meets the principle of the conservation of mass as the drug amount in each sublayer rather than the concentration at each subinterval is concerned in the ointment. The model is used to analyze the release of betamethasone 17‐valerate from a pressure‐sensitive silicone adhesive into a sink. The drug release from the 1.50 mg/mL patch shows no substantial discrepancy from that predicted by the classic suspension model assuming an infinite dissolution rate. However, the classic model overestimates the release from the 3.08 and 5.88 mg/mL patches. The disagreement is lessened when the dissolution rate is assumed to be finite. However, the model does not give a perfect explanation because the drug release from the 3.08 and 5.88 mg/mL patches in the early phase is faster than the model predicts.

In vitro release of betamethasone -17- valereate from various dermatological bases

AbstractBetamethasone -17- Valereate release characteristics, from several commercial dermatological bases, were evaluated before and after dilution with several excipients.It was found that betamethasone releases faster from creams than from ointments. In addition the release of the corticosteroid is affected by the composition of the diluting excipient.

In vitro release study of betamethasone and phenylephrine hydrochloride from ophthalmic preparations

The in vitro release of betamethasone and phenylephrine hydrochloride from ophthalmic solutions and gels was investigated. Linearization of release data of either drug or their combination was attempted according to zero-order, first-order and diffusion kinetics. The data obtained are directly in favour of a first-order mechanism both for betamethasone and phenylephrine hydrochloride and they show that the mechanism of drug release from solutions containing viscolizers or from hydrogels is independent of the nature of the drug in terms of its water solubility or ionization. The type of polymer or the increase in viscosity of the ophthalmic preparation do not indicate the release mechanism to any significant extent. The release rate constants of phenylephrine hydrochloride are consistently higher than those of betamethasone. The preparation based on carbomer is the only exception to this. The release rate constant of the drug is highly dependent on the viscosity of the ophthalmic solution. Below the critical viscosity of 5 cp a considerable lowering of the release rate constant takes place. In ophthalmic gel the release rate constant of either drug shows a very low dependency on the basic viscosity of the gel.