Abstract
For parenteral controlled drug release, the desired zero order release profile with no lag time is often difficult to achieve. To overcome the undesired lag time of the current commercial risperidone controlled release formulation, we developed PLGA–lipid microcapsules (MCs) and PLGA–lipid microgels (MGs). The lipid phase was composed of middle chain triglycerides (MCT) or isopropylmyristate (IPM). Hydroxystearic acid was used as an oleogelator. The three-dimensional inner structure of Risperidone-loaded MCs and MGs was assessed by using the invasive method of electron microscopy with focused ion beam cutting (FIB-SEM) and the noninvasive method of high-resolution nanoscale X-ray computed tomography (nano-CT). FIB-SEM and nano-CT measurements revealed the presence of highly dispersed spherical structures around two micrometres in size. Drug release kinetics did strongly depend on the used lipid phase and the presence or absence of hydroxystearic acid. We achieved a nearly zero order release without a lag time over 60 days with the MC-MCT formulation. In conclusion, the developed lipid-PLGA microparticles are attractive alternatives to pure PLGA-based particles. The advantages include improved release profiles, which can be easily tuned by the lipid composition.
Highlights
The use of parenteral controlled release drug delivery systems (CR-DDS) is a highly attractive and rational way to improve drug therapy
When particle formation was completed, the suspensions were transferred into a 500 mL round bottom flask and the remaining DCM were removed under vacuum 40 mbar for 20 min
The float-A Lyzer was placed into a 100 mL measuring cylinder and filled up with phosphate buffer saline (PBS) to the final volume of 60 mL so that the float-A Lyzer is submerged in PBS
Summary
The use of parenteral controlled release drug delivery systems (CR-DDS) is a highly attractive and rational way to improve drug therapy. An important application of CR-DDS is the controlled release of antipsychotic compounds to treat schizophrenia. Long-acting parenteral controlled release of antipsychotic drugs overcomes the poor compliance of patients with oral administration [7,8]. Several oral and one parenteral controlled release formulations are available and a PLGA based CR-DDS formulation is marketed (Risperdal® Consta®). The CR-DDS should provide a constant release over the 1–2 months without a lag time and the need for initial oral comedication. Increased drug loads may be achieved by the lipid component and the release rate might be controlled by the polymer shell. (ii) c(hiia) ractercihzaartaiocnteroifztahtieotnhorefeth-deimtherenes-idoinmaleinnsnioenrasltrinuncteurrsetroufcrtiusrpeeorifdroisnpee-rloidaodneed-lMoaCdsedanMdCMsGansdby using focMuGsesdbiyonusbinegamfoc(FuIsBe)dpiorenpbaeraamtio(nFIaBn)dptrhepreaer-adtiiomneannsdiotnharleXe--draimy eimnsaiogninagl X(n-raanyoi-mCaTg).ing (nano-CT)
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