An extended-release formulation of methotrexate for subcutaneous administration

Area of Science:

• Pharmacology
• Drug Delivery Systems
• Oncology

Background:

• Methotrexate is a cell-cycle specific antimetabolite requiring prolonged exposure for efficacy.
• Its short in vivo half-life necessitates frequent administrations, limiting therapeutic potential.
• Developing sustained-release formulations is crucial for improving methotrexate's therapeutic index.

Purpose of the Study:

• To develop and evaluate an extended-release formulation of methotrexate using a lipid-based drug delivery system.
• To assess the pharmacokinetic profile and anti-leukemia efficacy of the novel formulation in vivo.
• To determine if the extended-release formulation improves the therapeutic index of methotrexate.

Main Methods:

• Encapsulation of methotrexate into a lipid-based system to create Depo/methotrexate.
• Pharmacokinetic studies in BDF1 mice to measure plasma half-life and drug concentrations.
• Efficacy studies using the L1210 leukemia model in mice to assess anti-cancer activity.

Main Results:

• Depo/methotrexate increased the plasma half-life of methotrexate by 190-fold (0.53 to 100 hours).
• Peak plasma levels were 120-fold lower, while AUCs remained similar compared to unencapsulated methotrexate.
• Single-dose potency against L1210 leukemia increased approximately 130-fold with no significant change in the therapeutic index.

Conclusions:

• Depo/methotrexate demonstrates significantly prolonged drug release and enhanced anti-leukemia potency in a murine model.
• The lipid-based extended-release formulation shows potential for improved methotrexate therapy.
• Further investigation into Depo/methotrexate may offer a valuable alternative for cancer treatment.