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Stabilization of dichloromethane-induced protein denaturation during microencapsulation
R S Raghuvanshi1, S Goyal, O Singh
1National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India.
Pharmaceutical Development and Technology
|July 8, 1998
Summary
Dichloromethane (DCM) denatures protein drugs during microencapsulation, reducing immunoreactivity. Serum albumins and polyvinyl alcohol (PVA) effectively protect proteins like tetanus toxoid (TT) from DCM damage.
Area of Science:
- Biotechnology
- Pharmaceutical Sciences
- Materials Science
Background:
- Controlled-release drug delivery systems often utilize biodegradable polymers for drug encapsulation.
- The primary emulsification step in microencapsulation can expose sensitive protein drugs to organic solvents like dichloromethane (DCM).
- DCM is known to cause denaturation and loss of immunoreactivity in various protein drugs.
Purpose of the Study:
- To investigate the denaturation of protein drugs by dichloromethane (DCM) during microencapsulation.
- To evaluate the efficacy of stabilizers in preventing DCM-induced protein denaturation.
- To assess the impact of stabilization on the in vitro and in vivo immunoreactivity of encapsulated protein drugs.
Main Methods:
- Proteins including tetanus toxoid (TT), diphtheria toxoid (DT), ovine growth hormone (oGH), and human chorionic gonadotropin (beta-hCG-TT) were subjected to microencapsulation using DCM.
- Various stabilizers, such as serum albumins and polyvinyl alcohol (PVA), were incorporated during the primary emulsification step.
- Protein immunoreactivity was assessed in vitro, and antibody titers were measured in vivo after administration of stabilized TT in rats.
Main Results:
- DCM caused significant denaturation and precipitation of TT, DT, oGH, and beta-hCG-TT at the aqueous-organic interface, reducing their immunoreactivity.
- The B subunit of E. coli enterotoxin (LTB) exhibited relative stability towards DCM.
- Serum albumins and PVA demonstrated promising protective effects, preserving protein immunoreactivity.
- TT stabilized with serum albumin retained in vitro immunoreactivity and elicited comparable antibody titers in rats to native TT.
Conclusions:
- Dichloromethane (DCM) poses a significant risk of denaturation to protein drugs during microencapsulation.
- Incorporation of stabilizers, particularly serum albumins, can effectively mitigate DCM-induced protein denaturation.
- Stabilized protein drugs maintain their immunoreactivity and biological efficacy, enabling successful controlled-release applications.