Observation of the differences in pharmacokinetic effects of intravenous injection of Digilanid C combined with electroacupuncture at different time points

Background: The combination of acupuncture and medication can enhance efficacy and reduce toxicity. However, the mechanisms by which acupuncture influences drug efficacy and toxicity (enhancing efficacy/reducing toxicity) remain unclear. Objective: To investigate the effects of electroacupuncture (EA) administered at different time points relative to intravenous (i.v.) injection of Digilanid C on the pharmacokinetics and pharmacodynamics in normal rats. Methods: Sprague-Dawley male rats weighing 200 to 250 g were randomly divided into i.v. group, EA before i.v. group, EA with i.v. group, and EA after i.v. group. Animals received an i.v. injection of Digilanid C (0.1 mg/kg) and/or EA at the left Neiguan (PC6) acupoint. Blood samples ( n = 6) and heart samples ( n = 3) were collected at different time points after a single intervention. Data were recorded and analyzed using high-performance liquid chromatography–tandem mass spectrometry, and pharmacokinetic curves were constructed to evaluate the effects of EA administered at different time points on the pharmacokinetics of i.v. Digilanid C in normal rats. Kidney samples from the blank control group, i.v. group, EA before i.v. group, and EA with i.v. group were collected 30 minutes after intervention for Western blot analysis to detect drug accumulation in the body. In addition, left ventricular catheterization was performed to measure heart rate, as well as the maximum rates of rise and decline of left ventricular pressure, to observe the pharmacodynamic effects of Digilanid C, EA, and pre-EA administration. Results: High-performance liquid chromatography–tandem mass spectrometry analysis showed that, after i.v. injection of Digilanid C, the blood concentration in all groups reached the peak immediately. The EA before i.v. group and EA with i.v. group exhibited significantly higher concentrations than the i.v. group ( P < 0.01, P < 0.05), while no statistically significant difference was observed between the EA after i.v. group and the i.v. group. Cardiac drug concentrations in the i.v. group, EA before i.v. group, and EA with i.v. group peaked at 30 minutes, with significantly higher concentrations in the EA groups compared with the i.v. group ( P < 0.01). In contrast, the EA after i.v. group reached the peak cardiac drug concentration at 1 hour, and all EA groups showed higher levels than the i.v. group ( P < 0.01). Western blot analysis revealed that P-glycoprotein expression in the kidneys of the EA before i.v. and EA with i.v. groups was significantly lower than that in the i.v. group ( P < 0.05). Left ventricular catheterization showed that, after intervention, heart rate and ±d p /d t max increased in the i.v. group, EA group, and EA before i.v. group. Among these, the EA before i.v. group demonstrated the strongest effect ( P < 0.05), whereas the i.v. group and EA group exhibited comparable effects. Conclusion: EA administered at different time points influences the pharmacokinetics and effects of i.v. Digilanid C. Appropriate timing of acupuncture combined with medication may enhance drug efficacy by modulating pharmacokinetics and altering drug accumulation in vivo .