Glycyl-l-histidyl-l-lysine (GHK) dramatically boosts solubility and stability of poorly water-soluble drugs in co-amorphous systems.
Background
Many promising drug candidates face significant challenges due to poor aqueous solubility, leading to low oral bioavailability and variable therapeutic effects. Co-amorphous systems offer a strategy to improve drug solubility by forming a homogeneous amorphous phase with a co-former. However, traditional amino acid-based co-formers often yield limited dissolution enhancement and insufficient physical stability. This study addresses this gap by exploring glycyl-l-histidyl-l-lysine (GHK), a biocompatible tripeptide with multiple functional groups, as a novel co-former to overcome these formulation limitations and expand the design space for highly effective co-amorphous drug delivery systems.
Study Design
Researchers investigated glycyl-l-histidyl-l-lysine (GHK) as a novel co-former for poorly water-soluble drugs. They selected basic mebendazole, neutral tadalafil, and acidic indomethacin as model drugs. For comparison, glycine, histidine, and lysine were also tested as co-formers. All drug-co-former combinations were prepared by ball milling at a 1:1 molar ratio. The primary endpoints included assessing complete amorphization kinetics, homogeneity via differential scanning calorimetry (DSC), dissolution performance (rate, concentration, supersaturation), and physical stability over 6 months.
Results
GHK demonstrated superior performance, achieving complete amorphization with all three model drugs within just 15 min of ball milling, a stark contrast to most amino acid-based mixtures that remained partially crystalline even after 60 min. Homogeneous amorphous forms were confirmed by differential scanning calorimetry, showing a single glass transition temperature in the drug-GHK systems.
The drug-GHK systems exhibited significantly enhanced dissolution performance, including faster dissolution rates, higher drug concentration, and sustained supersaturation for up to 1440 min (24 hours) compared to both pure crystalline and amorphous drugs.
Furthermore, physical stability studies confirmed that GHK-based systems maintained their amorphous forms for at least 6 months, significantly outperforming both amino acid-based counterparts and pure amorphous drugs. These improvements in dissolution and physical stability were notably associated with the formation of salt formation and hydrogen bonding interactions between GHK and the model drugs.
Key Findings
- GHK achieved complete amorphization with model drugs within 15 min of
ball milling. - Drug-GHK systems showed a single glass transition temperature, confirming homogeneous amorphous forms.
- GHK-based systems significantly enhanced dissolution rates and drug concentration.
- Sustained supersaturation was observed for up to 1440 min (24 hours) with GHK.
- GHK systems maintained physical amorphous stability for at least 6 months.
- Improvements were linked to salt formation and hydrogen bonding interactions.
Why It Matters
GHK's utility significantly broadens beyond its known biological roles, positioning it as a powerful tool in pharmaceutical formulation. For peptide users and biohackers, understanding GHK's physicochemical properties as a co-former highlights its versatility and potential for novel applications. The ability of GHK to dramatically enhance drug solubility and stability could lead to more effective oral drug delivery systems, potentially improving the bioavailability of existing and future poorly soluble compounds. This could translate into lower effective doses, reduced side effects, and more consistent therapeutic outcomes. While this is a foundational study, it paves the way for developing new, highly stable, and bioavailable drug formulations, potentially impacting how various compounds are delivered and absorbed in the body.
ghk
drug formulation
solubility
stability
co-amorphous
oral bioavailability