CAPRO™ depot formulations pre-program release kinetics at the polymer level using cleavable linkers — zero burst release, no acidic byproducts, no organic solvents. Works for small molecules, biologics, and combination formulations. SubQ, IM, intra-articular, and biodegradable implant formats all supported.
These are the six reasons pharma companies convert approved oral drugs to long-acting injectables — and why every one of them applies to CAPRO™ depot programs.
PLGA, ISM (in-situ microparticle), lipid-based depots, and ion-pairing nanosuspensions each carry structural limitations that constrain drug types, duration, or safety. CAPRO™ was designed at the molecular level to address every one of them.
| Technical criterion | Polyester microspheres | In-situ forming implants | Lipid-based depots | CAPRO™ |
|---|---|---|---|---|
| Burst releaseDay-1 release as % of dose | 20–25% on day 1 — toxic peaks, depot depletion | Significant initial burst before polymer phase-inverts | Burst driven by rapid API partitioning at depot surface | Zero burst — cleavable linkers pre-program sustained release from first contact |
| Degradation productsWhat the polymer becomes in vivo | Lactic + glycolic acid — local acidification, inflammation | Same acidic degradation pathway; residual solvent adds regulatory burden | Metabolised lipids — generally safe but inflammatory responses at injection site | Non-toxic endotoxin-free small molecules — neutral pH, no inflammatory cascade |
| Organic solventsProcessing chemicals required | DCM or ethyl acetate — residual levels raise safety concerns | High-boiling polar solvent required — residual levels raise patient safety and regulatory concerns | Ethanol or other co-solvents often required for lipid processing | Completely solvent-free — physical mixing, zero residual solvent, full API integrity |
| Biologic compatibilityPeptides, proteins, nucleic acids | Heat, shear, and acidic in vivo environment denature biologics | Acidic in-vivo degradation and harsh solvent environment damage protein structure | Limited compatibility for fragile proteins; stability window is narrow | Room-temp mixing, neutral degradation — high protein activity retention post-formulation |
| Release predictabilityBatch-to-batch consistency | Polymer Mw, crystallinity, water uptake — significant batch variability | Phase-inversion kinetics affected by injection technique and tissue environment | Drug partitioning between lipid and aqueous phases variable across batches | Linker chemistry determines rate — highly predictable, reproducible across batches at any scale |
| Duration rangeAchievable release windows | Narrow practical window — Mw or particle size adjustment has limits | Typically weeks; extending duration requires formulation trade-offs | Mostly days to weeks; limited to molecules with suitable lipid partitioning | Days to months by linker selection — same blocks, different linker, entirely different duration. By design. |
| Drug loadingAPI % of total formulation | Typical 3–12% — large injection volumes, limits patient experience | Moderate loading; high concentrations limited by polymer solubility in NMP | Limited by drug's lipophilicity; hydrophilic drugs poorly retained | Higher loading achievable — compact, lower-volume formulations, smaller gauge needle possible |
| GMP scalabilityManufacturing complexity | Solvent emulsion, microsphere atomization, complex lyophilization — only 19 FDA approvals in 35+ years | Solvent handling and strict fill/finish requirements; cold chain storage | Temperature-sensitive manufacturing; sterile lipid handling adds complexity | Physical mixing — simple, scalable GMP-compatible process being developed alongside pre-clinical programs |
CAPRO™'s cleavable linker architecture supports every depot format. The release duration is programmed into the chemistry — not reverse-engineered from the manufacturing process.
CAPRO™ depot is most valuable where adherence is the primary barrier to outcomes, where consistent plasma levels matter clinically, or where LAI conversion creates meaningful commercial differentiation.
The API structure is never modified. CAPRO™ excipients deliver the molecule differently — so the full established safety database travels with the program all the way to NDA.
Whether you have an approved drug with adherence challenges, a biologic needing long-acting delivery, or a pain asset ready for IA depot conversion — Trekka has a structured path forward.