Characterization of captopril sublingual permeation: determination of preferred routes and mechanisms

Oral drug delivery for immunoengineering

The systemic pharmacotherapeutic efficacy of immunomodulatory drugs is heavily influenced by its route of administration. A few common routes for the systemic delivery of immunotherapeutics are intravenous, intraperitoneal, and intramuscular injections. However, the development of novel biomaterials, in adjunct to current progress in immunoengineering, is providing an exciting area of interest for oral drug delivery for systemic targeting. Oral immunotherapeutic delivery is a highly preferred route of administration due to its ease of administration, higher patient compliance, and increased ability to generate specialized immune responses. However, the harsh environment and slow systemic absorption, due to various biological barriers, reduces the immunotherapeutic bioavailability, and in turn prevents widespread use of oral delivery. Nonetheless, cutting edge biomaterials are being synthesized to combat these biological barriers within the gastrointestinal (GI) tract for the enhancement of drug bioavailability and targeting the immune system. For example, advancements in biomaterials and synthesized drug agents have provided distinctive methods to promote localized drug absorption for the modulation of local or systemic immune responses. Additionally, novel breakthroughs in the immunoengineering field show promise in the development of vaccine delivery systems for disease prevention as well as combating autoimmune diseases, inflammatory diseases, and cancer. This review will discuss current progress made within the field of biomaterials and drug delivery systems to enhance oral immunotherapeutic availability, and how these new delivery platforms can be utilized to deliver immunotherapeutics for resolution of immune-related diseases.

Effect of Fast-Disintegrating Tablets' Characteristics on the Sublingual Permeability of Atropine Sulfate for the Potential Treatment of Organophosphates Toxicity

Atropine sulfate (AS) fast-disintegrating sublingual tablets (FDSTs) were tested for AS sublingual permeation's feasibility as a potential alternative dosage form to treat organophosphates (OP) toxicity. More than 12,000 OP pesticide toxicity cases were reported in the USA from 2011 to 2014. AS is the recommended antidote for OP toxicity; however, it is only available as an ATROPEN® auto-injector, an IM injection, for self-administration, which is associated with several drawbacks and limitations. Six AS FDST batches were formulated and characterized. Two tablet sizes, group A weighing 150 mg and group B weighing 50 mg, were formulated with three different AS doses: 2 mg (A1 and B1), 4 mg (A2 and B2), and 8 mg (A3 and B3). AS in vitro diffusion and sublingual permeation were investigated in Franz cells using a cellulose membrane and an excised porcine sublingual membrane. The effect of AS load and tablet size on sublingual permeation was also evaluated. All batches passed quality control tests. AS FDSTs' size and AS load had a significant effect on tablet disintegration time and drug dissolution, which significantly impacted AS concentration gradient across the diffusional membrane. Group B FDSTs (smaller tablets) resulted in a significantly higher initial permeation (JAUC_0-15) compared to group A FDSTs. Also, the cumulative AS (JAUC_0-90) and AS influx (J) increased linearly with increasing AS dose. These AS FDSTs have the potential to be explored in vivo to determine the required bioequivalent sublingual AS dose as an alternative dosage form for the treatment of OP toxicity.

Evaluation of self-nanoemulsifying drug delivery systems using multivariate methods to optimize permeability of captopril oral films

The present report demonstrates a quality by design approach to understand and optimize self-nanoemulsifying orodispersible films (SNEODF) of captopril for hypertension. A central composite experimental design was used to study the formulation parameters effects (primary emulsion, aqueous phase, and surfactant) on the film properties (globule size, film burst, adhesion, Young's moduli, disintegration time, tensile strength and dissolution). Principle component analysis (PCA) and principle component regression (PCR) were employed to identify and quantify the effects of formulation variables and physico-mechanical properties of the film on the drug permeability. PCA classified three distinct groups of film formulations based on their composition and properties. PCR quantified the impact of main variables, their interactions, and square effects on the drug permeability. The main effect of the aqueous phase exhibited a negative impact, while that of flux and tensile strength showed a positive impact on the permeability. Interactions of primary emulsions with disintegration time and tensile strength displayed a synergistic impact. Interactions of aqueous phase with flux, Young's moduli, and tensile strength, as well as between Young's moduli and tensile strength showed a significant positive effect on the permeability. A negative correlation of square effects of primary emulsion and flux, and a positive square effect of Young's moduli confirmed their non-linear influence on the drug permeability across porcine buccal mucosa. This research work demonstrates application of design of experiment and multivariate methods to achieve targeted product quality of captopril (SNEODF) having improved permeability and pH independent release profile.

Solid dispersions in the form of electrospun core-sheath nanofibers

Background

The objective of this investigation was to develop a new type of solid dispersion in the form of core-sheath nanofibers using coaxial electrospinning for poorly water-soluble drugs. Different functional ingredients can be placed in various parts of core-sheath nanofibers to improve synergistically the dissolution and permeation properties of encapsulated drugs and to enable drugs to exert their actions.

Methods

Using acyclovir as a model drug, polyvinylpyrrolidone as the hydrophilic filament-forming polymer matrix, sodium dodecyl sulfate as a transmembrane enhancer, and sucralose as a sweetener, core-sheath nanofibers were successfully prepared, with the sheath part consisting of polyvinylpyrrolidone, sodium dodecyl sulfate, and sucralose, and the core part composed of polyvinylpyrrolidone and acyclovir.

Results

The core-sheath nanofibers had an average diameter of 410 ± 94 nm with a uniform structure and smooth surface. Differential scanning calorimetry and x-ray diffraction results demonstrated that acyclovir, sodium dodecyl sulfate, and sucralose were well distributed in the polyvinylpyrrolidone matrix in an amorphous state due to favoring of second-order interactions. In vitro dissolution and permeation studies showed that the core-sheath nanofiber solid dispersions could rapidly release acyclovir within one minute, with an over six-fold increased permeation rate across the sublingual mucosa compared with that of crude acyclovir particles.

Conclusion

The study reported here provides an example of the systematic design, preparation, characterization, and application of a novel type of solid dispersion consisting of multiple components and structural characteristics.

Formulation and pharmacodynamic evaluation of captopril sustained release microparticles

Cellulose propionate (CP) microparticles containing captopril (CAP) were prepared by solvent evaporation technique. The effects of polymer molecular weight, polymer composition and drug:polymer ratios on the particle size, flow properties, morphology, surface properties and release characteristics of the prepared captopril microparticles were examined. The anti-hypertensive effect of the selected CAP formulation in comparison with aqueous drug solution was also evaluated in vivo using hypertensive rats. The formulation containing drug:polymer blend ratio 1:1.5 (1:1 low:high molecular weight CP), namely F7, was chosen as the selected formulation with regard to the encapsulation efficiency (75.1%), flow properties (theta=24 degrees, Carr index=5%, Hausner ratio=1.1, packing rate=0.535) and release characteristics. Initial burst effect was observed in the release profile of all examined formulations. DSC and SEM results indicated that the initial burst effect could be attributed to dissolution of CAP crystals present on the surface or embedded in the superficial layer of the matrix. The release kinetics of CAP from most microparticle formulations followed diffusion mechanism. After oral administration of the selected microparticle formulation (F7) to hypertensive rats, systolic blood pressure decreased gradually over 24 h compared to reference drug solution. These results may suggest the potential application of cellulose propionate microparticles as a suitable sustained release drug delivery system for captopril.

Effect of pH on In Vitro Permeation of Ondansetron Hydrochloride Across Porcine Buccal Mucosa

The influence of drug concentration, pH in donor chamber, and 1-octanol/buffer partition coefficient on transbuccal permeation of ondansetron hydrochloride (pKa, 7.4) across porcine buccal mucosa was studied by using an in-line Franz type diffusion cell at 37 degrees C. The pH was adjusted to several values and the solubility of the drug in different pH was measured. Solubility of ondansetron hydrochloride decreases with increasing pH. The permeability of the drug was evaluated at different donor pH and drug concentrations. Permeability of un-ionized (Pu) and ionized (Pi) species of drug was calculated by fitting the data to a mathematical model. The steady state flux increased linearly with the donor concentration (r2 = 0.9843) at pH 7.4. The permeability coefficient and the partition coefficient of the drug increased with increasing pH. The values of Pu and Pi were 4.86 x 10(-6) cm/sec and 7.18 x 10(-7) (c)m/sec, respectively. The observed permeability coefficients and the permeability coefficients calculated from the mathematical model at various pH showed good linearity (r2 = 0.9799). The total permeability coefficient increased with increasing the fraction of un-ionized form of the drug. The drug permeated through buccal mucosa by a passive diffusion process. The non-ionized species of drug penetrated well through buccal mucosa and the permeation was a function of pH. Transbuccal delivery is a potential route for the administration of ondansetron hydrochloride.

Buccal penetration enhancers--how do they really work?

Certain agents that increase drug delivery through the skin, including surfactants, bile salts, and fatty acids, have been shown to exert a similar effect on the buccal mucosa. These agents enhance skin permeability by interacting with and disrupting the ordered intercellular lipid lamellae within the keratinized stratum corneum, and it has been assumed that a similar mechanism of action occurs in the nonkeratinized buccal mucosa. However, the chemical and structural nature of the lipids present within the intercellular regions of the buccal mucosa is quite different to that found within the stratum corneum, and so extrapolation of results between these two tissues may be misleading. To assume that the mechanism of action of buccal penetration enhancers is based on the disruption of intercellular lipids may be erroneous, and may result in the inappropriate prediction that certain skin penetration enhancers will similarly enhance drug delivery through the buccal mucosa. The data available in the literature suggest that agents that enhance buccal penetration exert their effect by a mechanism other than by disruption of intercellular lipids. Rather, buccal penetration enhancement appears to result from agents being able to (a) increase the partitioning of drugs into the buccal epithelium, (b) extract (and not disrupt) intercellular lipids, (c) interact with epithelial protein domains, and/or (d) increase the retention of drugs at the buccal mucosal surface. The purpose of this review is to identify the major differences in the structural and chemical nature of the permeability barriers between the buccal mucosa and skin, to clarify the mechanisms of action of buccal penetration enhancers, and to identify the limitations of certain models that are used to assess the effect of buccal penetration enhancers.