In vivo bioavailability and therapeutic assessment of host-guest inclusion phenomena for the hydrophobic molecule etodolac: pharmacodynamic and pharmacokinetic evaluation

A novel gedunin-2-hydroxypropyl-β-cyclodextrin inclusion complex improves anti-nociceptive and anti-inflammatory activities of gedunin in rodents

Gedunin is a bioactive compound, obtained from Entandrophragma angolense (EA), which has limited therapeutic usefulness due to poor aqueous solubility and first-pass effects. Cyclodextrins are cyclic oligosaccharides that form complexes with poorly soluble compounds, thus enhancing their pharmacological activity. In this article, we evaluated the pharmacological activities of gedunin-2-hydroxypropyl-β-cyclodextrin complex (GCD) in rodents. The antinociceptive activity of GCD (50, 100, 200 mg/kg) and Gedunin (50mg/kg) was tested in acetic acid-induced writhing and formalin-induced paw licking in mice. The anti-inflammatory activity was investigated in carrageenan-induced paw oedema and air pouch inflammation models in rats. Leucocytes counts, Tumour Necrosis Factor-alpha (TNF-α) level, nitric oxide, malondialdehyde, reduced glutathione, and myeloperoxidase enzyme activities were assessed in the air pouch exudate. The GCD (200mg/kg) significantly decreased writhing response, reduced licking duration and decreased oedema compared with gedunin and control. Exudate volume and leucocyte count were significantly reduced by GCD (200 mg/kg), it decreased myeloperoxidase activity and inhibited TNF-α release. The carrageenan-induced GSH depletion, increased malondialdehyde and nitrite levels were significantly reversed by GCD (200 mg/kg) relative to gedunin and control.  The GCD complex demonstrated significant antinociceptive and anti-inflammatory activities relative to gedunin alone via mechanisms associated with inhibition of oxidative stress and inflammation in rodents.

Enhanced Oral Bioavailability of Etodolac by the Liquisolid Compact Technique: Optimisation, In-Vitro and In-Vivo Evaluation

BACKGROUND

Poor dissolution of Etodolac is one of the major challenges in achieving the desired therapeutic effect in oral therapy.

OBJECTIVE

This study aimed to assess the potential of the liquisolid compact technique in increasing the rate of dissolution of Etodolac and thus its bioavailability.

METHODS

Liquisolid compacts were prepared using PEG 400, Avicel PH-200 and Aerosil 200 as non-volatile liquid, carrier and coating material, respectively. The optimisation was carried out by applying a 32 full factorial design using Design expert software 11.0.3.0 to examine the effects of independent variables (load factor and carrier: coating ratio) on dependent variables (angle of repose and % cumulative drug release at 30 min [Q <sub>30 min]). Assessment of bioavailability was based on a pharmacokinetic study on rabbits and pharmacodynamics evaluation on rats, respectively.

RESULTS

The formulation M3 was identified as the optimised formulation based on the better flow (lower angle of repose) and a higher rate of dissolution (Q ₃₀ min >95%). The higher dissolution rate could be due to conversion of Etodolac into an amorphous molecularly dispersed state, availability of larger surface area, enhancement of aqueous solubility and enhanced wetting of drug particles. Studies with DSC, XRD, and SEM verified the transformation of Etodolac from crystalline to amorphous state, a key factor responsible for improving the dissolution rate. The pharmacokinetic profile of M3 was prominent, demonstrating higher absorption of Etodolac in comparison to oral suspension and immediate-release conventional tablets in rabbits. Liquisolid formulation exhibited a 27% increment in paw thickness as compared to 57% and 46% increments for oral suspension and immediate-release conventional tablets, respectively, after 7 hrs in the carrageenan-induced paw model in rats.

CONCLUSION

The results indicated the liquisolid compact technique to be a promising strategy to enhance the bioavailability of Etodolac.

Investigation of inclusion behaviour of gefitinib with epichlorohydrin-β-cyclodextrin polymer: preparation of binary complex, stoichiometric determination and characterization

Gefitinib is anticancer drug which is sparingly soluble in water. This limits its dissolution and bioavailability. Binary inclusion complex of gefitinib with Epi-β-CD was prepared by freeze-drying method. Stoichiometric ratio of 1:1 M was established by continuous variation (Job's) plot. The stability constant of complex as determined by phase solubility study was found to be 15,871.3 M^-1. Complex was characterized by FTIR, DSC, DTA and dissolution study. Results revealed that in complex the drug no longer exist in crystalline state and is converted into amorphous form; which shows higher dissolution efficiency as compared to crystalline drug. The solubilizing efficiency for freeze dried complex was found to be 175.57 and the relative drug crystallinity degree was 87.91% as estimated by thermal analysis. Complexation led to decrease in surface tension; from 54.8 dynes/cm (pure gefitinib) to 40.3 dynes/cm (FD complex) due to adsorption phenomenon. The results obtained in this study confirmed that complexation of gefitinib with Epi-β-CD is a prominent approach and suitable tool for tailoring the issue related to its delivery and can be explored for development of an effective delivery system.

Effect of Polymers on the Physicochemical Properties and Biological Performance of Fenoprofen Calcium Dihydrate-Triacetyl-β-Cyclodextrin Complex

BACKGROUND

Fenoprofen calcium dehydrate (FCD) is counted as a non-steroidal, anti-inflammatory, anti-arthritic drug. FCD is slightly water soluble. It is indicated for mild pain relief, where the suggested dosage is 200 mg orally every 4 to 6 h.

AIM

Reduce dissolution efficiency, reach an extended therapeutic effect and reduce the frequency of the drug side effects.

METHOD

Combination of the co-evaporated drug:triacetyl-β-cyclodextrin complex prepared in a ratio of 1:3 and either of two polymers-hydroxylpropylmethyl cellulose (HPMC) or ethyl cellulose (EC)-in the same formulation. Invitro dissolution studies were carried in simulated gastric (pH 1.2) and intestinal (pH 6.8) fluids, by using the USP dissolution tester (rotating paddle apparatus). The FCD in vitro release from EC/drug complex was markedly retarded. Interaction between fenoprofen, TA-β-CD, EC, HPMC in the solid state were confirmed by FT-IR, DSC, XRD and SEM. In vivo studies assessed the anti-inflammatory and analgesic activities and the results were compared with the market product Nalfosab® Capsules.

RESULTS

Remarkable inhibition of inflammation and nociception after 24 h was attained for EC/drug complex.

CONCLUSIONS

EC/drug complex has a sustained effect due to high remaining amount after elapsing with remarkable inhibition of inflammation.

Supramolecular Complexation of Carbohydrates for the Bioavailability Enhancement of Poorly Soluble Drugs

In this review, a comprehensive overview of advances in the supramolecular complexes of carbohydrates and poorly soluble drugs is presented. Through the complexation process, poorly soluble drugs could be efficiently delivered to their desired destinations. Carbohydrates, the most abundant biomolecules, have diverse physicochemical properties owing to their inherent three-dimensional structures, hydrogen bonding, and molecular recognition abilities. In this regard, oligosaccharides and their derivatives have been utilized for the bioavailability enhancement of hydrophobic drugs via increasing the solubility or stability. By extension, polysaccharides and their derivatives can form self-assembled architectures with poorly soluble drugs and have shown increased bioavailability in terms of the sustained or controlled drug release. These supramolecular systems using carbohydrate will be developed consistently in the field of pharmaceutical and medical application.

Enhanced analgesic activity by cyclodextrins - a systematic review and meta-analysis

INTRODUCTION

Analgesics can be ineffective in treating some types of pain, hence, improved drug delivery systems could optimize their efficacy.

AREA COVERED

The authors conducted a systematic review to evaluate the analgesic activity of compounds complexed in cyclodextrins, analyzing whether these complexes improved analgesic efficacy. The search terms 'analgesics', 'cyclodextrins' and 'drug effects' were used to retrieve articles in SCOPUS, PUBMED and EMBASE. A total of 22 papers were identified. In the clinical studies, there was greater efficacy in the complexed drug when compared with control groups, with differences ranging from 25 to 83%. Through a meta-analysis, the preclinical studies showed that the complexed drug had a significantly (p < 0.01) greater effect than the non-complexed drug.

EXPERT OPINION

The use of cyclodextrins can improve the efficacy of analgesic compounds, and they are an important tool in the search for greater analgesic effect. They may also be a way to reduce the therapeutic doses, and hence increasing the potential of the drug.

Pharmacokinetics of cyclodextrins and drugs after oral and parenteral administration of drug/cyclodextrin complexes

Objectives

The objective of the present study was to shed some light on pharmacokinetics of cyclodextrins (CDs) and drugs after oral and parenteral administration of inclusion complexes.

Key findings

The complex binding constant in water can predict pharmacokinetics after parenteral administration, but it has to be considered in the context of the physiological environment, where plasma proteins compete with CDs for drug binding. Neither drug/CD nor drug/protein complexes can extravasate, but differently from proteins, CDs are readily cleared through glomerular filtration. In such intricate interrelationships, for complexes with low-to-mid binding constant, binding of drug to plasma proteins will mainly dictate the pharmacokinetics. Oppositely, for drugs showing large CD complex binding constant and low protein binding, significant decrease in distribution volume and enhanced excretion of unmetabolized drug are observed; thus, relevant changes in bioavailability can be predicted. In the case of oral administration, volume for dilution/dissolution of the complexes is relatively low and hence excess CD can hamper drug absorption from the gastrointestinal (GI) tract.

Summary

CDs are well-established multipurpose excipients for overcoming organoleptic and biopharmaceutical deficiencies of a variety of drugs. Balances between free and complexed drug in the GI tract and between drug–CD binding and drug–protein binding in plasma seem to play a relevant role in drug pharmacokinetics.