Systemic Absorption from Oral Vancomycin: Check the Dose!

In vitro and in vivo local tolerability of a synergistic anti-tuberculosis drug combination intended for pulmonary delivery

A drug combination, vancomycin (VAN) plus tetrahydrolipstatin (THL), has demonstrated an effective synergistic action in vitro against Mycobacterium tuberculosis (Mtb). The poor oral bioavailability of VAN and THL and the predominant tropism of Mtb infection to the lungs make their pulmonary administration very attractive. To evaluate their local tolerability, bronchial cells, alveolar cells and monocytes were exposed to concentrations around and above their minimal inhibitory concentration (MIC). The VAN had no inhibitory activity on the tested human cell lines, even at a concentration 125 times higher than its MIC, whereas the THL, alone or in combination with VAN, presented a cytostatic action. Monolayer epithelium showed no significant irreversible damage at concentrations up to 100 times the combination MIC. BALB/cAnNRj mice exposed to concentration of 50 times the combination MIC delivered endotracheally 3 times a week for 3 weeks showed no clinical signs or significant weight loss. The increase of proinflammatory biomarkers (i.e., IL-1, IL-6, TNF-α and proportion of inflammatory cells) and cytotoxicity in bronchoalveolar lavage fluid (BALF) were non-significant. Lung histopathology did not show significant tissue damage. The VAN/THL combination at doses up to 50 times the combination MIC is found to be thus well tolerated by pulmonary route. This study is a promising result and encouraging further investigations of pulmonary administration of VAN/THL combination as dry powder for anti-tuberculosis treatment.

Review of high dose vancomycin in the treatment of Clostridioides difficile infection

BACKGROUND

Guidelines recommend oral vancomycin as first-line therapy for Clostridioides difficile infection. Guideline recommendations vary regarding dosing of vancomycin. Our aim was to summarize the current evidence on the efficacy and adverse effects of high dose oral and vancomycin retention enema (>500 mg/day) for the treatment of C. difficile infection.

METHODS

We searched clinical studies and major guidelines in the English language using MEDLINE, the Cochrane Library and Embase from 1985 until 15 April 2020.

RESULTS

No evidence supports the use of high dose oral vancomycin in the treatment of severe C. difficile infection. Weak evidence from observational studies supports the use of high dose oral vancomycin in addition to intravenous metronidazole and high dose vancomycin retention enema in fulminant C. difficile infection. Vancomycin retention enema can be used in severe C. difficile infection when oral administration is not possible, or in conditions when the oral formulation cannot reach the colon such as Hartman's pouch, ileostomies, or colon diversions.

CONCLUSIONS

The dosing schedules for oral vancomycin and vancomycin enemas are not clearly defined due to widely varying results in clinical studies. Large, comparative multicenter trials are urgently needed to define the role of high dose vancomycin in C. difficile infection.

New Insights Into the Pharmacokinetics of Vancomycin After Oral and Intravenous Administration: An Investigation in Beagle Dogs

Intestinal absorption of orally administered peptides is often negligible because one or more key requirements for successful absorption (water solubility, peptic resistance, mucosal permeation) are not met. Due to its high water solubility and stability in the gastro-intestinal tract, vancomycin is an ideal model peptide for evaluating the factors influencing the critical step of mucosal permeation. Therefore, to support formulation development for the systemic oral delivery of peptide therapeutics, we investigated the pharmacokinetics of vancomycin in beagle dogs after intravenous and oral administration comparing enteric encapsulated drug to the drug in solution, which revealed mean absolute bioavailabilities of 0.27% and 1.66%, respectively. Additionally, in depth pharmacokinetic analyses of intravenously administered vancomycin revealed a deep compartment slowly releasing the compound over many hours into the blood.