Influence of curcumin on the pharmacodynamics and pharmacokinetics of gliclazide in animal models

Type-1 diabetes: Lessons from a decade of preclinical studies on phytotherapy

BACKGROUND

In recent decades, numerous herbal products have been shown to have antihyperglycemic and beta cell-regenerative effects in animal studies. However, there is no clinical evidence that those products completely cure patients with type-1 diabetes (T1D). Therefore, it seems that most of the phytochemicals do not have a significant impact on human beta cells, and the results of experimental studies conducted on them may not be generalizable to the clinic.

PURPOSE

The present work aims to review extensively the methods and results of preclinical studies on phytotherapy of T1D published in the last 10 years.

METHODS

This paper critically analyzes the designs of studies, treatment protocols, methods of diabetes induction, characteristics of the studied animals, clinical relevance, reproducibility of research, and other aspects related to conducting preclinical studies on T1D. We discussed limitations that make many of the results of these studies not generalizable to the clinic. Finally, some recommendations were given to improve studies on the phytotherapy of T1D to avoid misleading interpretations about the antidiabetic effect of herbal compounds.

CONCLUSION

This paper can be considered a practical guide for researchers interested in the field of phytotherapy of T1D to increase the reliability, reproducibility, and validity of their preclinical studies.

Combination Therapy: A New Tool for the Management of Obesity

Obesity is a chronic lifestyle issue with devastating results. Behavioral changes are one of the initial lines of management strategies for obesity, but they are not very efficient management strategies. Many people also use surgical intervention to maintain a healthy weight, now considered to be the most common and effective obesity management. Chemically synthesized medicines fill the gap between lifestyle interventions and minimally invasive surgical management of obesity. The most common issue associated with monotherapy without side effects is its moderate effectiveness and higher dose requirement. Combination therapy is already used for many serious and complicated disease treatments and management and has shown efficacy as well. Generally, we use two or more medicines with different mechanisms of action for a better effect. The commonly used combination therapy for obesity management includes low-dose phentermine and prolonged and slow-releasing mechanism topiramate; naltrexone, and bupropion. Phentermine with inhibitors of Na-glucose cotransporter-2 or glucagon-like peptide-1 (GLP-1) agonists with gastric hormone or Na-glucose cotransporter-2 are two more viable combo therapy. This combination strategy aims to achieve success in bariatric surgery and the scientific community is working in this direction.

Changes in Pharmacokinetics and Pharmacodynamics of Losartan in Experimental Diseased Rats Treated with Curcuma longa and Lepidium sativum

The current study investigated “pharmacodynamics and pharmacokinetics interactions” of losartan with Curcuma longa (CUR) and Lepidium sativum (LS) in hypertensive rats. Hypertension was induced by oral administration of L-NAME (40 mg/kg) for two weeks. Oral administration of CUR or LS shows some substantial antihypertensive activity. The systolic blood pressure (SBP) of hypertensive rats was decreased by 7.04% and 8.78% 12 h after treatment with CUR and LS, respectively, as compared to rats treated with L-NAME alone. LS and CUR display the ability to potentiate the blood pressure-lowering effects of losartan in hypertensive rats. A greater decrease in SBP, by 11.66% and 13.74%, was observed in hypertensive rats treated with CUR + losartan and LS + losartan, respectively. Further, both the investigated herbs, CUR and LS, caused an increase in plasma concentrations of losartan in hypertensive rats. The AUC0-t, AUC0-inf and AUMC0-inf of losartan were increased by 1.25-fold, 1.28-fold and 1.09-fold in hypertensive rats treated with CUR + losartan. A significant (p < 0.05) increase in AUC0-t (2.41-fold), AUC0-inf (3.86-fold) and AUMC0-inf (8.35-fold) of losartan was observed in hypertensive rats treated with LS + losartan. The present study affirms that interactions between CUR or LS with losartan alter both “pharmacokinetics and pharmacodynamics” of the drug. Concurrent administration of losartan with either CUR or LS would require dose adjustment and intermittent blood pressure monitoring for clinical use in hypertensive patients. Additional investigation is necessary to determine the importance of these interactions in humans and to elucidate the mechanisms of action behind these interactions.

Effect of C. cyminum and L. sativum on Pharmacokinetics and Pharmacodynamics of Antidiabetic Drug Gliclazide

BACKGROUND

Numerous herbs are reported to have anti-hyperglycemic activity and are frequently used in combination with prescription drugs to lower the blood glucose levels in diabetic patients, without proper knowledge about the possibility of herb-drug interaction.

OBJECTIVES

To investigate the effect of cumin and garden cress on pharmacokinetics (PK) and pharmacodynamics (PD) of gliclazide (GLZ) in nicotinamide-streptozotocin diabetic model.

METHODS

Diabetic animals of groups II-IV were treated with GLZ, cumin, 'cumin + GLZ', garden cress and 'garden cress + GLZ'. Herb's treatments were given for two weeks, and GLZ was administered in a single dose. Blood glucose levels (BGLs) were measured at pre-determined time points. Plasma samples of pharmacokinetic study were analyzed using UPLC-MS/MS. GLZ fragment at m/z 324.1>127 was monitored.

RESULTS

Cumin and garden cress have shown 15.3% and 15.9% reduction in mean BGL (1-24h) (p-value < 0.001), respectively. GLZ reduced mean BGL by 30.0%, which was significantly better than cumin and garden cress (pvalue <0.05). Concurrently administered "garden cress + GLZ" demonstrated the highest reduction in mean BGL (by 40.46%) and showed a prolonged effect. There was no significant advantage of simultaneously administered 'cumin + GLZ'. Cumin did not affect PK of GLZ. Garden cress has significantly enhanced AUC_0-t (by 69.8%, pvalue 0.0013), but other PK parameters C_max, T_max, and Kel were close to the control group.

CONCLUSION

PK/PD-based herb-drug interaction was observed. Concurrently administered garden cress + GLZ showed improved antidiabetic effect and has enhanced GLZ bioavailability.

Enhancing Bioavailability and Stability of Curcumin Using Solid Lipid Nanoparticles (CLEN): A Covenant for Its Effectiveness

Curcumin, very rightly referred to as "a wonder drug" is proven to be efficacious in a variety of inflammatory disorders including cancers. Antiaging, anti-inflammatory, antioxidant, antitumor, chemosensitizing, P-gp efflux inhibiting, and antiproliferative activity are some of the striking features of curcumin, highlighting its importance in chemotherapy. Curcumin inhibits Bcl-2, Bcl-XL, VEGF, c-Myc, ICAM-1, EGFR, STAT3 phosphorylation, and cyclin D1 genes involved in the various stages of breast, prostate, and gastric cancer proliferation, angiogenesis, invasion, and metastasis. The full therapeutic potential of curcumin however remains under explored mainly due to poor absorption, rapid metabolism and systemic elimination culminating in its poor bioavailability. Furthermore, curcumin is insoluble, unstable at various pH and is also prone to undergo photodegradation. Nanotechnology can help improve the therapeutic potential of drug molecules with compromised biopharmaceutical profiles. Solid lipid nanoparticles (SLNs) are the latest offshoot of nanomedicine with proven advantages of high drug payload, longer shelf life, biocompatibility and biodegradability, and industrial amenability of the production process. We successfully developed CLEN (Curcumin encapsulated lipidic nanoconstructs) containing 15 mg curcumin per ml of the SLN dispersion with highest (till date, to our knowledge) increase in solubility of curcumin in an aqueous system by 1.4 × 106 times as compared to its intrinsic solubility of 11 ng/ml and high drug loading (15% w/v with respect to lipid matrix). Zero-order release kinetics observed for CLEN versus first order release for free curcumin establish controlled release nature of the developed CLEN. It showed 69.78 times higher oral bioavailability with respect to free curcumin; 9.00 times higher than a bioavailable marketed formulation (CurcuWIN®). The formulation showed 104, 13.3, and 10-times enhanced stability at pH 6.8, 1.2, and 7.4, respectively. All these factors ensure the efficacy of CLEN in treating cancer and other inflammatory diseases.

Interaction of p-synephrine on the pharmacodynamics and pharmacokinetics of gliclazide in animal models

Background

Type 2 diabetes is frequently seen in patients suffering from obesity. p-synephrine and gliclazide are widely used medicines for the treatment of obesity and diabetes, respectively.

Objectives

The present study was undertaken to determine the potential for interactions between p-synephrine and gliclazide, based on the relationship between obesity and diabetes.

Methods

Influence of p-synephrine on the activity of gliclazide was determined by conducting single and multiple dose interaction studies in animal models. Blood samples collected at pre-determined time intervals from experimental animals were used for the estimation of glucose and insulin levels. The insulin resistance and β-cell function were determined by homeostasis model assessment. Additionally, serum gliclazide levels in rabbits were analyzed by high-performance liquid chromatography (HPLC).

Results

Gliclazide alone showed peak reduction in blood glucose levels at 2 and 8 h after administration in rats and after 3 h in rabbits. The activity of gliclazide was not altered by a single dose treatment with p-synephrine. However, in multiple dose interaction studies, samples from all the time points analyzed showed significant changes in percent blood glucose reduction ranging from 19.73 to 44.18% in normal rats, 23.76–46.43% in diabetic rats and 16.36–38.34% in normal rabbits. The homeostasis model assessment parameters were also significantly altered in multiple dose interaction studies. The pharmacokinetics of gliclazide was not altered by either single or multiple dose p-synephrine treatments in rabbits.

Conclusion

The effect of multiple dose p-synephrine treatments upon gliclazide appeared to be pharmacodynamic in nature, indicating the need for periodic monitoring of glucose levels and dose adjustment as necessary when this combination is prescribed to obese patients.

Curcumin as a clinically-promising anti-cancer agent: pharmacokinetics and drug interactions

INTRODUCTION

Curcumin has been extensively studied for its anti-cancer properties. While a diverse array of in vitro and preclinical research support the prospect of curcumin use as an anti-cancer therapeutic, most human studies have failed to meet the intended clinical expectation. Poor systemic availability of orally-administered curcumin may account for this disparity. Areas covered: This descriptive review aims to concisely summarise available clinical studies investigating curcumin pharmacokinetics when administered in different formulations. A critical analysis of pharmacokinetic- and pharmacodynamic-based interactions of curcumin with concomitantly administered drugs is also provided. Expert opinion: The encouraging clinical results of curcumin administration are currently limited to people with colorectal cancer, given that sufficient curcumin concentrations persist in colonic mucosa. Higher parent curcumin systemic exposure, which can be achieved by several newer formulations, has important implications for optimal treatment of cancers other than those in gastrointestinal tract. Curcumin-drug pharmacokinetic interactions are also almost exclusively in the enterocytes, owing to extensive first pass metabolism and poor curcumin bioavailability. Greater scope of these interactions, i.e. modulation of the systemic elimination of co-administered drugs, may be expected from more-bioavailable curcumin formulations. Further studies are still warranted, especially with newer formulations to support the inclusion of curcumin in cancer therapy regimens.