In Vitro Permeation Studies on Carvedilol Containing Dissolving Microarray Patches Quantified Using a Rapid and Simple HPLC-UV Analytical Method.

Analytical method validation is a vital element of drug formulation and delivery studies. Here, high-performance liquid chromatography in conjunction with UV detection (HPLC-UV) has been used to produce a straightforward, quick, yet sensitive analytical approach to quantify carvedilol (CAR). A C18 column was used to isolate the analyte from the mixture by isocratic elution with a mobile phase comprising a mixture of 0.1% v/v trifluoroacetic acid in water and acetonitrile in a ratio of 65:35 v/v at a flow rate of 0.6 mL min-1. Linearity was observed for CAR concentrations within the range of 1.5-50 µg mL-1 (R2 = 0.999) in phosphate buffer saline and within the range of 0.2-6.2 µg mL-1 (R2 = 0.9999) in methanol. The International Council on Harmonization (ICH) requirements were followed throughout the validation of the isocratic approach, rendering it specific, accurate, and precise. Moreover, robustness tests indicated that the method remained selective and specific despite small deliberate changes to environmental and operational factors. An efficient extraction procedure was also developed to extract and quantify CAR from excised neonatal porcine skin, resulting in recovery rates ranging from 95 to 97%. The methods reported here have been successfully utilised to evaluate CAR permeation, both transdermally and intradermally following application of a dissolving microarray patch (MAP) to excised neonatal porcine skin.

Tip loaded cyclodextrin-carvedilol complexes microarray patches.

Carvedilol, a ß-blocker prescribed for chronic heart failure, suffers from poor bioavailability and rapid first pass metabolism when administered orally. Herein, we present the development of tip microarray patches (MAPs) composed of ternary cyclodextrin (CD) complexes of carvedilol for transdermal delivery. The ternary complex with hydroxypropyl γ-cyclodextrin (HPγCD) and poly(vinyl pyrrolidone) (PVP) reduced the crystallinity of carvedilol, as evidenced by DSC, XRD, NMR, and SEM analysis. MAPs were fabricated using a two-step process with the ternary complex as the needle layer. The resulting MAPs were capable of breaching ex vivo neonatal porcine skin to a depth ≈600 µm with minimal impact to needle height. Upon insertion, the needle dissolved within 2 h, leading to the transdermal delivery of carvedilol. The MAPs displayed minimal toxicity and acceptable biocompatibility in cell assays. In rats, MAPs achieved significantly higher AUC levels of carvedilol than oral administration, with a delayed Tmax and sustained plasma levels over several days. These findings suggest that the carvedilol-loaded dissolving MAPs have the potential to revolutionise the treatment of chronic heart failure.

Primaquine and chloroquine nano-sized solid dispersion-loaded dissolving microarray patches for the improved treatment of malaria caused by Plasmodium vivax.

Malaria is a global parasitic infection that leads to substantial illness and death. The most commonly-used drugs for treatment of malaria vivax are primaquine and chloroquine, but they have limitations, such as poor adherence due to frequent oral administration and gastrointestinal side effects. To overcome these limitations, we have developed nano-sized solid dispersion-based dissolving microarray patches (MAPs) for the intradermal delivery of these drugs. In vitro testing showed that these systems can deliver to skin and receiver compartment up to ≈60% of the payload for CQ-based dissolving MAPs and a total of ≈42% of drug loading for PQ-based dissolving MAPs. MAPs also displayed acceptable biocompatibility in cell tests. Pharmacokinetic studies in rats showed that dissolving MAPs could deliver sustained plasma levels of both PQ and CQ for over 7 days. Efficacy studies in a murine model for malaria showed that mice treated with PQ-MAPs and CQ-MAPs had reduced parasitaemia by up to 99.2%. This pharmaceutical approach may revolutionise malaria vivax treatment, especially in developing countries where the disease is endemic. The development of these dissolving MAPs may overcome issues associated with current pharmacotherapy and improve patient outcomes.

Intestinal Absorption Study: Challenges and Absorption Enhancement Strategies in Improving Oral Drug Delivery.

The oral route is the most common and practical means of drug administration, particularly from a patient's perspective. However, the pharmacokinetic profile of oral drugs depends on the rate of drug absorption through the intestinal wall before entering the systemic circulation. However, the enteric epithelium represents one of the major limiting steps for drug absorption, due to the presence of efflux transporters on the intestinal membrane, mucous layer, enzymatic degradation, and the existence of tight junctions along the intestinal linings. These challenges are more noticeable for hydrophilic drugs, high molecular weight drugs, and drugs that are substrates of the efflux transporters. Another challenge faced by oral drug delivery is the presence of first-pass hepatic metabolism that can result in reduced drug bioavailability. Over the years, a wide range of compounds have been investigated for their permeation-enhancing effect in order to circumvent these challenges. There is also a growing interest in developing nanocarrier-based formulation strategies to enhance the drug absorption. Therefore, this review aims to provide an overview of the challenges faced by oral drug delivery and selected strategies to enhance the oral drug absorption, including the application of absorption enhancers and nanocarrier-based formulations based on in vitro, in vivo, and in situ studies.

Design and Development of Levodopa Loaded Polymeric Nanoparticles for Intranasal Delivery.

Intranasal delivery is an alternative administration route to deliver levodopa (L-Dopa) to the brain. This drug delivery route offers high drug permeability across the nasal epithelium and rapid absorption into the central nervous system (CNS) while bypassing first-pass metabolism. In this study, we developed a library of polymeric nanocarrier systems for L-Dopa utilising poly(lactic-co-glycolic acid) (PLGA) and chitosan. A total of three PLGA nanoparticles formulations (P1, P2 and P3) were prepared using a modified water-in-oil-in-water (W/O/W) solvent evaporation technique, while four formulations of chitosan nanoparticles (C1, C2, C3 and C4) were prepared by ionic gelation method with sodium tripolyphosphate (TPP) as a cross-linking agent. Upon characterising nanocarriers developed, it was discovered that C2 demonstrated the best results with regard to droplet size (553 ± 52 nm), polydispersity index (0.522), zeta potential (+46.2 ± 2.3 mV), and encapsulation efficiency (82.38% ± 1.63). Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) further corroborated the particle size analysis highlighting that C2 displayed uniform particle size with spherical morphology. Additionally, X-ray diffraction analysis (XRD) revealed that C2 was in an amorphous state while Fourier transform infrared (FTIR) analysis showed that there were no chemical interactions that might change the chemical structure of L-Dopa within the polymeric nanoparticle matrix. Lastly, an in-vivo intranasal study in male Wistar rats showed that the absorption of L-Dopa when formulated as chitosan nanoparticles was significantly enhanced (p < 0.05) by approximately two-fold compared to unmodified L-Dopa. Therefore, this work illustrates that formulating L-Dopa into chitosan nanoparticles for intranasal delivery is a potentially viable formulation strategy to improve the bioavailability of the drug for the treatment of Parkinson's disease.

Physical Characterisation and Stability Study of Formulated Chromolaena odorata Gel.

BACKGROUND: Formulation of topical products for skin delivery that fulfill good formulation criteria has always been a challenge for pharmaceutical scientists. Despite the challenges, gelbased drug delivery offers some advantages such that it is non-invasive, painless, involves avoidance of the first-pass metabolism, and has satisfactory patient compliance. OBJECTIVES: In this study, C. odorata gel and quercetin gel (bioactive flavonoid compound) were successfully formulated and compared with placebo and conventional wound aid gel. The chromatographic profiling was conducted to screen the presence of phytoconstituents. Subsequently, all formulated gels were evaluated for physical characteristics and stability. METHODS: Reverse Phase High-Performance Liquid Chromatography (RP-HPLC) of C. odorata methanolic leaves extract showed a distinct compound separation at a retention time of 8.4min to 34.8 min at 254nm. All gels were characterised by evaluating their rheological properties, including storage modulus, loss modulus, and plastic viscosity. Besides, texture analysis was performed to measure the firmness, consistency, cohesiveness, and viscosity index of the gels. RESULTS: According to the results, C. odorata gel demonstrated better spreadability as compared to the other gels, which required less work and was found to be favourable for application on the skin. Moreover, C. odorata gel showed no changes in organoleptic properties and proven to be stable after 30 days of accelerated stability study at 40°C ± 2°C with Relative Humidity (RH) of 75% ± 5%. CONCLUSION: C. odorata gel was found to be stable, reflecting the combination of materials used in the formulation, which did not degrade throughout the study. This work suggests the potential of this gel as a vehicle to deliver the active ingredients of C. odorata to the skin, which can be further explored as a topical application for antimicrobial wound management or other skin diseases study.

The effect of wellsolve, a novel solubilizing agent, on the intestinal barrier function and intestinal absorption of griseofulvin in rats.

The effect of Wellsolve, a new solubilizing agent, on the function of intestinal membrane barrier and transporters including P-glycoprotein (P-gp) and peptide transporter (PEPT1) was examined by an in vitro diffusion chamber and an in situ closed loop method. The model drugs used in this study were 5(6)-carboxyfluorescein (CF), rhodamine123 (a P-glycoprotein substrate), cephalexin (a typical substrate for PEPT1) and griseofulvin (a BCS Class II drug). Intestinal absorption of CF was not affected by the addition of 1-10% (v/v) Wellsolve, while 20% (v/v) Wellsolve significantly enhanced its intestinal absorption by the in situ absorption study. Therefore, this finding suggested that high concentration of Wellsolve might alter the intestinal barrier function. The mucosal to serosal (absorptive) and serosal to mucosal (secretory) transport of rhodamine123 was significantly inhibited in the presence of 5.0-20% (v/v) of Wellsolve, suggesting that Wellsolve might not affect the function of P-gp in the intestine. The intestinal transport of cephalexin was not affected in the presence of Wellsolve, suggesting that this solubilizing agent might not change the function of PEPT1 in the intestine. In the toxicity studies, we found that 1-10% (v/v) Wellsolve did not change the release of lactate hydrogenase (LDH) and protein from the intestinal membranes. Furthermore, intestinal absorption of griseofulvin in the presence of 10% (v/v) Wellsolve significantly increased as compared with the control. In summary, Wellsolve at lower concentrations might be a potent and safe solubilizing agent for improving the solubility and absorption of poorly water-soluble drugs including griseofulvin.

Polyamidoamine dendrimers can improve the pulmonary absorption of insulin and calcitonin in rats.

The absorption-enhancing effects of polyamidoamine (PAMAM) dendrimers with various generations (G0-G3) and concentrations [0.1%-1.0% (w/v)] on the pulmonary absorption of peptide and protein drugs were studied in rats. Insulin and calcitonin were chosen as models of peptide and protein drugs, and their pulmonary absorption with or without PAMAM dendrimers was examined by in vivo pulmonary absorption studies. PAMAM dendrimers significantly increased the pulmonary absorption of insulin and calcitonin in rats, and their absorption-enhancing effects were generation dependent. The rank order of absorption enhancement effect of these PAMAM dendrimers was G3 > G2 > G1 > G0. For the same generation, the absorption-enhancing effects of PAMAM dendrimers were shown to be concentration dependent. The toxicity of these PAMAM dendrimers in the lung tissues was evaluated by measuring the release of protein and the activities of lactate dehydrogenase (LDH) in bronchoalveolar lavage fluid (BALF). The PAMAM dendrimers with various generations and concentrations did not significantly increase the release of protein and the activities of LDH in BALF, indicating that these dendrimers did not cause any membrane damage to the lung tissues. The zeta potentials of insulin and calcitonin solutions changed to positive by the addition of PAMAM dendrimers, and the degree of positive charge as determined by the zeta potentials was linearly correlated with the absorption-enhancing effects of the PAMAM dendrimers. This positive charge of the PAMAM dendrimers might be related to their absorption-enhancing mechanisms for improving the pulmonary absorption of insulin and calcitonin in rats. In conclusion, the PAMAM dendrimers are suitable absorption enhancers to improve the pulmonary absorption of insulin and calcitonin without any membrane damage to the respiratory tissues.

The effects of common solubilizing agents on the intestinal membrane barrier functions and membrane toxicity in rats.

The use of solubilizing agents to improve the solubility of poorly water-soluble drugs often results in an alteration of intestinal membrane barrier function and intestinal membrane damage. In this study, 5(6)-carboxyfluorescein (CF) and fluorescein isothiocyanate-labeled dextran (MW 4400, FD4) were used as model compounds to examine the effects of twelve common solubilizing agents, sodium taurocholate (NaTC), Labrasol, polyethylene glycol 400 (PEG 400), Transcutol P, propylene glycol, Gelucire 44/14, HCO-60, ethanol, Cremophor EL, Tween 80, 2 hydroxypropyl-beta-cyclodextrin (2HP-beta-CyD) and dimethylsulfoxide (DMSO), on intestinal membrane barrier function and membrane toxicity in rats. Intestinal transport and absorption of CF were examined using an in vitro diffusion chamber and an in situ closed-loop technique. The in vitro diffusion chamber study showed that only 5 and 10% (w/v) NaTC significantly increased the transport of CF across the intestinal membrane. The in situ closed-loop study showed a remarkable increase in the absorption of CF and a bioavailability of more than 30% in the presence of 5 and 10% (v/v) Labrasol, 5 and 10% (w/v) NaTC and 10% (v/v) Transcutol P. Furthermore, we evaluated the effect of NaTC and Labrasol on the intestinal absorption of FD4, a high molecular weight compound. The results indicated that the absorption of FD4 also increased in the presence of 5 and 10% (w/v) NaTC and 10% (v/v) Labrasol, suggesting that these concentrations of NaTC and Labrasol may alter the intestinal membrane barrier functions in rats. We measured the release of protein and lactate dehydrogenase (LDH) from the intestinal membrane to examine the safety of solubilizing agents in the intestine. 5 and 10% (w/v) NaTC and 5 and 10% (v/v) Gelucire 44/14 significantly increased the presence of these toxicity markers compared to the control. The LDH level was also increased in the presence of 10% (v/v) of Cremophor EL. These findings suggest that the solubilizing agents at these concentrations except for NaTC, Gelucire 44/14 and Cremophor EL are considered safe and do not cause intestinal membrane damage. In conclusion, this study provides a basic approach in screening and predicting the effects of solubilizing agents for intestinal absorption studies using drugs poorly soluble in water.