Effect of Repeated Low-Dose Organophosphorothionate Pesticide Exposure on Digoxin Pharmacokinetics in Rats; a Possible Interaction Involving P-Glycoprotein

Fenpropathrin increases gliquidone absorption via causing damage to the integrity of intestinal barrier

Fenpropathrin is a commonly used pesticide, which was ingested by humans through diet and water. Gliquidone is a common hypoglycemic drug that diabetic patients need for long-term use. This study aimed to investigate the effects of long-term exposure to fenpropathrin on the intestinal barrier and intestinal absorption of the model drug gliquidone. The Ussing Chamber study had shown that fenpropathrin can increase the transport of gliquidone in an isolated intestinal model. In addition, the intestinal absorption of fluorescein was significantly increased in fenpropathrin-exposed rats administered by gavage. Further research suggested that fenpropathrin exposure caused a series of pathological effects: the structure of the intestine was damaged, the expression of tight junction proteins in the intestinal tissue was decreased, the intestinal MDA was increased, the SOD was decreased, and the expression of inflammatory factors was increased. In the Caco-2 cell model, it was found that fenpropathrin can increase the transport of gliquidone in the Caco-2 cell monolayer, reduce the expression of tight junction proteins and increase reactive oxygen species in Caco-2 cells. Fenpropathrin exposure also resulted in decreasing expression of PPAR-γ and UCP-2 in intestinal tissue and Caco-2 cell model, while causing increased expression of p-P38. The above results indicated that fenpropathrin exposure could induce oxidative stress and destroy the intestinal barrier by affecting the expression of p-P38/P38/PPAR-γ/UCP-2 protein, thereby increasing the intestinal absorption of gliquidone. This study provides new insights into the hazards of fenpropathrin residues in the environment.

Changes in digoxin pharmacokinetics associated with hepatic P-glycoprotein upregulation in rats with non-alcoholic fatty liver disease

BACKGROUND & OBJECTIVES

Upregulation of hepatic P-glycoprotein (P-gp) expression has been reported in patients with non-alcoholic fatty liver disease (NAFLD) and rodent models thereof. Here, we explored the changes hepatic P-gp expression and activity in a NAFLD rat model and the effects thereof on the pharmacokinetics of digoxin (a probe substrate of P-gp).

METHODS

Rats were fed a 1% (w/w) orotic acid-containing diet for 20 days to induce NAFLD; control rats received a normal diet. P-gp expression and biliary digoxin excretion were examined. The pharmacokinetics of digoxin were evaluated after it had been administered intravenously (10 μg·kg^-1 ) and orally (200 μg·kg^-1 ) to control and NAFLD rats.

RESULTS

The total areas under the plasma concentration-time curves (AUCs) of digoxin after intravenous and oral administration were significantly smaller (by 39.1% and 73.0%, respectively) in NAFLD rats because of faster biliary digoxin excretion, reflecting elevations of hepatic P-gp expression and activity. Notably, the steady-state volume of distribution rose by 98.2%, while extent of oral bioavailability fell by 55.5% in NAFLD rats.

CONCLUSION

This is the first study to report digoxin pharmacokinetic changes caused by hepatic P-gp upregulation in NAFLD. Further studies are needed to explore the clinical impact of enhanced P-gp-mediated biliary excretion on pharmacotherapies using P-gp substrates in patients with NAFLD.

Restoration and Enhancement of Immunogenic Cell Death of Cisplatin by Coadministration with Digoxin and Conjugation to HPMA Copolymer

Complete tumor eradication is the ultimate goal of cancer therapy. However, the majority of anticancer drugs cause nonimmunogenic cell death and only exert on-site anticancer activities. The intrinsic genomic instability of cancer allows for the persistence and later expansion of treatment-resistant clones after surviving a sort of Darwinian selection of chemotherapy. Additional incorporation of immunotherapy, which is robust and individualized could be game-changing. Herein, we report a combination strategy that delivers nonimmunogenic cell death inducer Cisplatin to treat primary tumors and converts the tumor cells into vaccines that spurs a long-lasting immune response against residual tumors to prevent tumor recurrence and metastasis. Cisplatin(IV) prodrug was linked to the N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer (P-Cis) and coadministered with digoxin (Dig), which eventually launched two attacks to cancer cells. First, P-Cis exhibited superior tumor retention and cytotoxicity over free Cisplatin (to inhibit the primary tumor growth). Then, Dig reversed the inability of Cisplatin to trigger calreticulin exposure, and HPMA copolymer-amplified Cisplatin-induced ATP release. These complementary mechanisms induced potent immunogenic cell death that promotes dendritic cell maturation and activates CD8⁺ T cell responses. In established tumor models, P-Cis + Dig combination completely eradicate tumors with no residual cancer cells remaining. Cancer cells succumbing to P-Cis + Dig could protect syngeneic mice against the subsequent challenge with living cells of the same type and stimulated robust abscopal and antimetastatic effects. Such a strategy might be promising to restore the immunogenicity of nonimmunogenic drugs and generate vaccine-like functions for improved immunochemotherapy.