In vitro and in vivo effects of selected fibers on the pharmacokinetics of orally administered carbamazepine: Possible interaction between therapeutic drugs and semisolid enteral nutrients

Effect of Thickening Agents on the In Vitro Antibacterial Activity of Vancomycin Hydrochloride Powder

When vancomycin hydrochloride (VCM) powder mixes with xanthan gum-based thickening agents in food, lumps or other property-related changes may occur. Previous studies have reported delayed disintegration and elution of the drug and its adsorption on to xanthan gum, which is the main ingredient of thickened food products. If the addition of thickening agents can affect the antimicrobial activity of VCM powder as previously reported, it might interfere with the treatment of Clostridioides difficile infection (CDI). In this study, we investigated the effect of the addition of xanthan gum-based thickening agents on the antibacterial activity of VCM against Clostridioides difficile in vitro. The VCM concentration at 0 min after adding 3% Tsururinko Quickly (Clinico, Tokyo) to VCM powders (Shionogi, Osaka and Meiji Seika Pharma, Tokyo) was lower than that of the control [Shionogi: 65.15±35.57%, Meiji Seika Pharma: 77.00±15.81% (mean±standard deviation), ** p<0.01, Dunnet's test]. However, the VCM concentration at 30 min after the addition recovered to the control level. The drug susceptibility tests for C. difficile and Staphylococcus aureus using the disk diffusion method showed no effect of addition of 3% Tsururinko Quickly. Our in vitro evaluations showed that the addition of xanthan gum-based thickeners to VCM powders had a negligible effect on the treatment of CDI.

Study on enteral nutrient components causing decreased gastric phenytoin absorption

BACKGROUND

Previously, we revealed that coadministration of particular enteral nutrients (ENs) decreases plasma concentrations and gastric absorption of phenytoin (PHT), an antiepileptic drug, in rats; however, the mechanism has not been clarified.

METHODS

We measured the permeability rate of PHT using a Caco-2 cell monolayer as a human intestinal absorption model with casein, soy protein, simulated gastrointestinal digested casein protein (G-casein or P-casein) or simulated gastrointestinal digested soy protein (G-soy or P-soy), dextrin, sucrose, degraded guar gum, indigestible dextrin, calcium, and magnesium, which are abundant in the ENs, and measured the solution's properties.

RESULTS

We demonstrated that casein (40 mg/ml), G-soy or P-soy (10 mg/ml), and dextrin (100 mg/ml) significantly decreased the permeability rate of PHT compared with the control. By contrast, G-casein or P-casein significantly increased the permeability rate of PHT. We also found that the PHT binding rate to casein 40 mg/ml was 90%. Furthermore, casein 40 mg/ml and dextrin 100 mg/ml have high viscosity. Moreover, G-casein and P-casein significantly decreased the transepithelial electrical resistance of Caco-2 cell monolayers compared with casein and the control.

CONCLUSION

Casein, digested soy protein, and dextrin decreased the gastric absorption of PHT. However, digested casein decreased PHT absorption by reducing the strength of tight junctions. The composition of ENs may affect the absorption of PHT differently, and these findings would aid in the selection of ENs for orally administered PHT.

Effects of concurrent and staggered dosing of semi-solid enteral nutrients on pharmacokinetic behavior of antiepileptic drugs after oral administration in rats

Background

The use of enteral nutrients plays a highly important role in accurate nutrition management, but limited information is currently available on the cautionary points of semi-solid enteral nutrients.

Aim

In this study, we examined whether the pharmacokinetic profiles of sodium valproate (SVA), levetiracetam (LEV), and carbamazepine (CBZ) are affected by altering the dosing time of RACOL^®-NF Semi Solid for Enteral Use (RASS), a prescribed semi-solid formula. We also investigated whether the pharmacokinetic interaction observed in this study can be avoided by staggered dosing of the chemical drug and semi-solid enteral nutrient.

Methods

The plasma concentration of SVA, LEV and CBZ after oral administration was measured by LC-MS/MS method.

Results

There was no difference in pharmacokinetic characteristics of SVA and LEV when the dosing time of RASS was altered. On the other hand, the plasma concentration of CBZ after oral administration at all sampling points decreased with the extension of the dosing time of RASS, which was consistent with the C_max and AUC. However, no significant difference was observed in the pharmacokinetic profiles or parameters of CBZ between the short-term and long-term RASS dosing groups by prolonging the administered interval of CBZ and RASS for 2 hr.

Conclusion

We concluded that the pharmacokinetic profiles of CBZ, but not SVA and LEV, after its oral administration are affected by the dosing time of RASS, but staggered administration of CBZ and RASS prevented their interaction.

Effects of semi-solidification of enteral nutrients on the pharmacokinetic behavior of orally administered carbamazepine in rats

The use of semi-solid enteral nutrients plays an extremely important role in accurate nutrition management. In the present study, we compared the pharmacokinetic profile of orally administered carbamazepine (CBZ) in rats treated with liquid RACOL^®, semi-solid RACOL^®, and HINE E-gel^®, which are enteral nutrients marketed in Japan. Since liquid and semi-solid formulations are both marketed in Japan for RACOL^®, liquid RACOL^® was orally administered to control rats. The serum concentration of CBZ at each sampling point was lower in the semi-solid RACOL^®-treated group than in the liquid RACOL^®-treated group. No significant differences were observed in the pharmacokinetic behavior of CBZ between the semi-solid RACOL^®-treated and HINE E-gel^®-treated groups. Regarding pharmacokinetic parameters, the impact of the area under the curve (AUC_0→5h) was the liquid RACOL^® group > the semi-solid RACOL^® group ≈ the HINE E-gel^® group. Therefore, we concluded that serum concentrations of CBZ were lower when concurrently treating with semi-solid enteral nutrients than when simultaneously processing liquid enteral nutrients.