Chitosan-telmisartan polymeric cocrystals for improving oral absorption: In vitro and in vivo evaluation

Nanotechnology-Based Strategies for Extended-Release Delivery of Angiotensin Receptor Blockers (ARBs): A Comprehensive Review

There has been a significant shift in the perception of hypertension as an important contributor to the global disease burden. Approximately 6 % and 8 % of pregnancies are affected by hypertension, which can adversely affect the mother and the fetus. Furthermore, a hypertensive individual is at increased risk of developing kidney disease, arterial hardening, eye damage, and strokes. Using angiotensin receptor blockers (ARBs) is widespread in treating hypertension, heart failure, coronary artery disease, and diabetic nephropathy. Despite this, some ARBs have limited use due to their poor oral bioavailability and water solubility. To tackle this, a variety of nanoparticle (NP)-based systems, such as polymeric NPs (i. e., dendrimers), polymeric micelles, polymer-drug conjugates, lipid NPs, nanoemulsions, self-emulsifying drug delivery systems (SEDDS), solid lipid NPs (SLNs), nanostructured lipid carriers (NLCs), carbon-based nanocarriers, inorganic NPs, and nanocrystals, have been recently developed for efficient delivery of losartan, Valsartan (Val), Olmesartan (OLM), Telmisartan (TEL), Candesartan, Eprosartan, Irbesartan, and Azilsartan to target cells. This review article provides a literature-based comparison of the various classes of ARBs, their mechanisms of action, and an overview of the nanoformulations developed for ARB delivery and successfully applied to managing hypertension, diabetic complications, and other conditions.

Telmisartan-Loaded Lactosylated Chitosan Nanoparticles as a Liver Specific Delivery System: Synthesis, Optimization and Targeting Efficiency

Hepatocellular carcinoma (HCC) has a significant economic impact and a high mortality rate. Telmisartan (TLM) is a potential therapy for HCC, but it has a limited scope in drug delivery due to unpredictable distribution and poor bioavailability. The objective of this study was to prepare, design, and in vitro evaluate lactose-modified chitosan nanoparticles (LCH NPs) as a liver-targeted nanocarrier for TLM with the potential to offer a promising HCC therapy. The combination of chitosan with lactose was successfully attained using the Maillard reaction. TLM-LCH NPs were prepared, characterized, and optimized with the developed 2³ full factorial design. The optimized formulation (F1) was in vitro and in vivo characterized. LCH was synthesized with an acceptable yield of 43.8 ± 0.56%, a lactosylation degree of 14.34%, and a significantly higher aqueous solubility (6.28 ± 0.21 g/L) compared to native chitosan (0.25 ± 0.03 g/L). In vitro characterization demonstrated that, F1 had a particle size of 145.46 ± 0.7 nm, an entrapment efficiency of 90.21 ± 0.28%, and a surface charge of + 27.13 ± 0.21 mV. In vitro TLM release from F1 was most consistent with the Higuchi model and demonstrated significantly higher release at pH 5.5. Moreover, a significantly higher ratio of liver to plasma concentration was observed with TLM-LCH NPs compared to plain TLM and unmodified TLM-NPs. The obtained results nominate TLM-LCH NPs as a promising carrier for enhancing liver targeting of TLM in treatment of HCC.

Promising strategies for improving oral bioavailability of poor water-soluble drugs

INTRODUCTION

Oral administration of poorly water-soluble drugs (PWSDs) is generally related to low bioavailability, leading to high drug doses, multiple side effects, and low patient compliance. Thus, different strategies have been developed to increase drug solubility and dissolution in the gastrointestinal tract, opening new venues for these drugs.

AREAS COVERED

This review outlines the current challenges in PWSD formulation development and the strategies to overcome the oral barriers and increase their solubility and bioavailability. Conventional strategies include altering crystalline and molecular structures and modifying oral solid dosage forms. In contrast, novel strategies comprise micro- and nanostructured systems. Recent representative studies involving how these strategies have improved the oral bioavailability of PWSDs were also reviewed and reported.

EXPERT OPINION

New approaches to enhance PWSD bioavailability have sought to improve water solubility and dissolution rates, drug protection by overcoming biological barriers, and increased absorption. Still, only a handful of studies have focused on quantifying the increase in bioavailability. Improving the oral bioavailability of PWSDs remains an exciting unexplored field of research and has become an important issue for successfully developing pharmaceutical products.

Enhanced Skin Permeation and Controlled Release of β-Sitosterol Using Cubosomes Encrusted with Dissolving Microneedles for the Management of Alopecia

The use of synthetic medication for treating alopecia is restricted because of systemic exposure and related negative effects. Beta-sitosterol (β-ST), a natural chemical, has lately been studied for its potential to promote hair development. The cubosomes with dissolving microneedles (CUBs-MN_D) created in this study may be a useful starting point for the creation of a sophisticated dermal delivery system for β-ST. Cubosomes (CUBs) were prepared by the emulsification method, using glyceryl monooleate (GMO) as a lipid polymer. CUBs were loaded with dissolving microneedles (MN_D) fabricated with HA and a PVP-K90 matrix. An ex vivo skin permeation study and an in vivo hair growth efficacy test of β-ST were performed with both CUB and CUB-MN_D. The average particle size of the CUBs was determined to be 173.67 ± 0.52 nm, with a low polydispersity index (0.3) and a high zeta potential value that prevents the aggregate formation of dispersed particles. When compared to CUBs alone, CUBs-MN_D displayed higher permeating levels of β-ST at all-time points. In the animals from the CUB-MN_D group, significant hair development was observed. According to the results of the current investigation, CUBs that integrate dissolving microneedles of β-ST are superior in terms of transdermal skin penetration and activity for the treatment of alopecia.

Optimization and In Vitro Characterization of Telmisartan Loaded Sodium Alginate Beads and Its In Vivo Efficacy Investigation in Hypertensive Induced Animal Model

BACKGROUND

Antihypertensive drug telmisartan (TEL) belongs to BCS class II, which is characterized by low water solubility and, consequently, low oral bioavailability. Gastroretentive systems may overcome the problems associated with low solubility of TEL and incomplete absorption by localizing the drug release in the stomach. The purpose of this study was to prepare TEL-loaded, oil-entrapped, floating alginate beads with the intent of enhancing the oral bioavailability of TEL for the treatment of hypertension.

METHODS

For the formulation and optimization of seventeen formulations of TEL-loaded oil-entrapped floating alginate beads, a central composite design was utilized. The concentration of sodium alginate (X1), the concentration of cross-linker (X2), and the concentration of sesame oil (X3) served as independent variables, whereas the entrapment efficiency (Y1), in vitro buoyancy (Y2), and drug release Q6h (Y3) served as dependent variables. Using the emulsion gelation method and calcium chloride as the cross-linking agent, different formulations of TEL alginate beads were produced. All formulations were evaluated for their entrapment efficiency percentage, in vitro buoyancy, and in vitro drug release. The optimal formulation of TEL alginate beads was prepared with and without oil and evaluated for entrapment efficiency percentage, in vitro buoyancy, swelling ratio, average size, and in vitro drug release. Using scanning electron microscopes, the surface morphology was determined. Using IR spectroscopy, the compatibility between the ingredients was determined. In vivo evaluation of the optimized formulation in comparison to the free TEL was done in hypertension-induced rats, and the systolic blood pressure and all pharmacokinetic parameters were measured.

RESULTS

The prepared beads exhibited a high entrapment efficiency percentage, in vitro buoyancy, and prolonged drug release. TEL was compatible with other ingredients, as approved by IR spectroscopy. The prepared TEL beads were spherical, as shown by the SEM. The relative bioavailability of TEL-loaded oil-entrapped beads was 222.52%, which was higher than that of the pure TEL suspension. The prepared TEL beads formulation exhibited a higher antihypertensive effect for a prolonged time compared to pure TEL suspension.

CONCLUSIONS

It can be concluded that this innovative delivery method of TEL-loaded oil-entrapped beads is a promising tool for enhancing drug solubility and, thus, oral bioavailability and therapeutic efficacy, resulting in enhanced patient compliance. Furthermore, the in vivo study confirmed the formulation's extended anti-hypertensive activity in animal models.

Unlocking the potential of drug-drug cocrystals - A comprehensive review

Intensive research subjected to the improvement of solubility and bioavailability of certain drugs has popularized the formation of cocrystals, wherein the desired drug is non-ionically bonded to a coformer by means of weak bonds. This paper addresses how crystal engineering of two compatible drug components can enhance the physicochemical and therapeutic properties of either or both of the drugs, resulting in drug-drug cocrystals, with pertinent examples. The paper also discusses the continuous screening processes which are replacing the traditional methods of crystallization due to numerous benefits to the producer as well as the products. Although faced with certain regulatory and scale-up constraints, cocrystals provide immense opportunities to the field of novel drug development.

Solid State Characterization and Dissolution Enhancement of Nevirapine Cocrystals

Purpose: Novel cocrystals of nevirapine (NP) were designed and prepared with salicylamide and 3-hydroxy benzoic acid (3-HBA).

Methods: The cocrystals were prepared by solvent drop grinding method by adding few drops of acetone to enhance the solubility and dissolution. The drug and cocrystals were characterized by differential scanning calorimetry (DSC) and powder x-ray diffraction (PXRD). The solubility of NP, its wet ground form, and cocrystals were investigated at different pH. Moreover, the effect of surfactant on solubility of cocrystals was also studied. Finally, intrinsic dissolution rate (IDR) and stability of cocrystals was examined.

Results: The characterization of cocrystals by DSC and PXRD revealed formation of new solid forms due to changes in thermogram and PXRD pattern. The cocrystal of NP with 3-HBA showed 4.5 folds greater solubility in pH 1.2 buffer and 5.5 folds in 1% Tween 80 as compared to original drug. IDR of cocrystals was higher than the pure drug in 0.1 N hydrochloric acid (HCl). Moreover, cocrystals were found physically stable after 3 months as evident from unchanged IDR.

Conclusion: Hence, the present research indicates the new stable solid forms of NP with improved dissolution rate than pure drug.

Development of a naftopidil-chitosan-based fumaric acid solid dispersion to improve the dissolution rate and stability of naftopidil

Naftopidil (NAF), an α₁-adrenoceptor antagonist, is administered as a treatment for benign prostatic hyperplasia; however, according to the Biopharmaceutical Classification System (BCS IV), it is a poorly-soluble drug that exhibits poor permeability. We aimed to increase the dissolution (%) of NAF by adding chitosan to a polymer-free formulation. Compared to the formulation prepared using Flivas®, at 60 min, the solid dispersion (SD) formulation containing NAF, fumaric acid, chitosan, and US2® in a 1:1:2:1 weight ratio improved the dissolution (%) of NAF in distilled water, pH 1.2 media, pH 4.0 and pH 6.8 buffers by 27.2-, 1.2-, 1.1- and 6.5-fold, respectively. The physicochemical properties of the SD1 formulation were also found to be altered, including its thermal properties, crystal intensity, and chemical interaction. As a result, the hydrogen bonding that occurs between NAF and fumaric acid was identified as a major factor in the increase in NAF dissolution (%). Further, chitosan was observed to contribute to the stability of NAF and SD1, which was assessed over a 3-month period. To our knowledge, this is the first study to employ a polymer-free system to improve the solubilization of NAF.

Study on the solubilization of telmisartan by forming cocrystals with aromatic carboxylic acids

The solubility of insoluble telmisartan could be greatly improved by forming cocrystals with aromatic carboxylic acids.

Solubilization of tadalafil using a tartaric acid and chitosan-based multi-system

Solubilization studies of tadalafil (TDF) have recently improved the dissolution (%) using weak acids and bases in our group. However, the weak acid formulations have a low dissolution (%) of TDF as limitation. Thus, the purpose of this study was to improve the dissolution (%) of TDF over 90% in distilled water (DW) by weak acid-chitosan based multi-system. The SD formulation (SD11: TDF, tartaric acid, chitosan, Aerosil®200, and PVP/VA S-630 in a 1:2:1:1:2 weight ratio) showed higher dissolution (%) of TDF by 5.0-, 6.0-, and 5.8-fold at 60 min than that of Cialis® in DW and pH 1.2 and pH 6.8 buffers, respectively. The physical properties of the SD11 formulation were changed. Moreover, the SD11 formulation maintained stability for 3 months. In conclusion, the solubilization of TDF using chitosan was successfully performed for the first time.

Development of L-Lysine Amino Acid-Based Co-Crystal of Telmisartan Using Crystal Engineering Approach to Improve Solubility, Dissolution, and Micrometric Properties

AIM

To develop a co-crytsal of Telmisartan for enhancing its solubility in water.

BACKGROUND

Intermolecular interaction happens in crystal packing; it utilizes and helps to understand the design of new solid with their respective chemical and physical properties called crystal engineering. It is a blueprint of molecular solids with specific chemical and physical properties through an understanding and handling of intermolecular interaction for increasing the solubility, in case of poor water-soluble drugs.

OBJECTIVES

The study was taken under consideration with an aim to generate and synthesize a cocrystal form of Telmisartan (TEL) with L-lysine to improve its water solubility, dissolution, and micrometric properties.

METHODS

Using dry grinding technique, solvent evaporation and cooling crystallization, the results revealed a generation of co-crystals with enhanced solubility by liquid drop grinding method. Hence, this process was further explored to investigate various formulations and process parameters that could significantly affect the crystal solubility, dissolution, and micrometric properties.

RESULTS

The solubility of TEL co-crystals was enhanced by L-lysine. Further, the optimized batch was subjected to its micrometric evaluation and physiochemical characterization like FT-IR, NMR, PXRD. The result of the micrometric evaluation showed better results as compared to standards. The dissolution studies also showed a better dissolution rate for TEL co-crystal tablets than TEL tablets formulation.

CONCLUSION

Co-crystals of TEL with L-lysine showed better solubility and dissolution rate.

The Role of Functional Excipients in Solid Oral Dosage Forms to Overcome Poor Drug Dissolution and Bioavailability

Many active pharmaceutical ingredients (APIs) exhibit poor solubility and low dissolution rates in aqueous environments such as the luminal fluids of the gastrointestinal tract. The oral bioavailability of these compounds is usually very low as a result of their poor solubility properties. In order to improve the bioavailability of these poorly soluble drugs, formulation strategies have been applied as a means to improve their aqueous solubility and dissolution rates. With respect to formulation approaches, excipients can be incorporated in the formulation to assist in the dissolution process of the drug, or specialized dosage forms can be formulated that improve dissolution rate through various mechanisms. This paper provides an overview of selected excipients (e.g., alkalinizing agents, surfactants and sugars) that can be used in formulations to increase the dissolution rate as well as specialized dosage forms such as self-emulsifying delivery systems and formulation techniques such as inclusion complexes and solid dispersions. These formulation approaches are discussed with available examples with specific reference to positive outcomes in terms of drug solubility and bioavailability enhancement.

How tenofovir disoproxil fumarate can impact on solubility and dissolution rate of efavirenz?

Efavirenz (EFZ) and tenofovir disoproxil fumarate (TDF) can be used simultaneously in the treatment of human immunodeficiency virus type1 infection. In this work the impact of TDF, a hydrophilic drug, on the solubility and dissolution rate of EFZ, a poorly water-soluble drug, was evaluated. EFZ/TDF binary mixtures in different molar ratios were prepared. Differential scanning calorimetry (DSC) results indicate the formation of a eutectic mixture, the molar ratio of 65/35 being the eutectic point. It was observed an increase in the EFZ solubility in water and acidic conditions (0.1 N HCl and biorelevant medium), in the presence of TDF. On the other hand, there was a decreasing on EFZ solubility in phosphate buffer pH 6.8, probably influenced by the lower solubility of TDF in this medium. The high solubility of TDF in water and acidic medium may have contributed to improve the solubility of EFZ, as well as the formation of a eutectic mixture, supported by X-ray powder diffraction (XRPD) and Fourier Transform infrared spectroscopy (FTIR) analyses. However, TDF solubility and dissolution rate was not significantly influenced by the presence of EFZ.