# Enantiomeric Excess Bupivacaine in a Lavender Oil NLC Tested in a Melanoma Model: Prolonged Release and Anticancer Effect

## TL;DR

This study shows that encapsulating bupivacaine in a nanostructured lipid carrier with lavender oil can prolong drug release and improve cancer treatment outcomes.

## Contribution

The novel use of a nanostructured lipid carrier with lavender oil to prolong bupivacaine's antitumor effect is demonstrated.

## Key findings

- Encapsulated bupivacaine in NLC showed 70% tumor growth inhibition compared to 17% with free bupivacaine.
- NLC formulations prolonged drug half-life by about six times compared to free bupivacaine.
- All BVCS75 treatments improved animal survival rates without synergistic effects from lavender oil.

## Abstract

Recent studies have highlighted the potential of local
anesthetics
(LA) as adjuvants in cancer treatment, specifically by increasing
survival rates when used in surgical excisions. However, the clinical
use of LA is restricted due to their systemic toxicity. The development
of drug delivery systems could address this issue and advance the
utilization of these molecules. In this research, we explored the
pharmacokinetics (using microdialysis probes) and antitumor properties
of a nanostructured lipid carrier (NLC) formulation containing the
commercially available enantiomeric excess form of bupivacaine (BVCS75). This NLC was prepared with lavender oil (NLC-L-BVC),
an excipient with inherent antitumor properties. We compared this
formulation to a control (NLC-BVC) using synthetic lipids. Pharmacokinetic
assessments of the NLCs confirmed the sustained release of BVCS75 within the tumor, characterized by a reduced elimination
rate constant and longer half-life (∼6×). The encapsulation
of BVCS75 within nanoparticles (whether natural or synthetic)
enhanced its effectiveness in treating the primary tumor, resulting
in the inhibition of tumor growth (70% with NLC-L-BVC and 72% with
NLC-BVC), outperforming free BVC (17% inhibition). However, the association
of lavender oil with BVCS75 in an NLC did not yield synergistic
properties. Furthermore, all BVCS75 treatments (whether
free or encapsulated) improved animal survival rates. These findings
confirm that encapsulation of bupivacaine in NLC can prolong drug
action at the local site, contributing to improved local antitumor
therapy while mitigating systemic effects.