Multiresponse Optimization of HPLC Method: Simultaneous Estimation of Protease Inhibitors and NNRTI in Human Plasma.

Multiresponse optimization approach to develop a simple isocratic, highly sensitive and accurate HPLC method for the simultaneous determination of Efavirenz, Atazanavir, Lopinavir and Ritonavir in human blood plasma along with carvedilol as an internal standard. Optimized the factors (ACN, buffer concentration and flow rate) effecting and interacting with the responses (k1, Rs2,1, Rs3,2 and tR5) applying Central Composite Design a chemometric tool. All the mathematical models as well as response surfaces were defined and derived for the separation using this strategy. Chromatography was performed on Thermo Hypersil C18 column using mobile phase comprising of ACN: 10 mM KH2PO4 (51.2:48.8) with 1 mL min-1 flow rate and detection wavelength was fixed at 210 nm. The analysis time was within 9 min. The method developed was validated by following "Bioanalytical method validation" [USFDA-CDER, 2001]. The developed method can be applied for bioavailability and pharmacokinetic studies.

Ethyl cellulose coated sustained release aspirin spherules for treating COVID-19: DOE led rapid optimization using arbitrary interface; applicable for emergency situations.

This work attempts to resolve one of the key issues related to the design and development of sustained-release spherule of aspirin for oral formulations, tailored to treat COVID-19. For that, in the Design of Experiments (DOE) an arbitrary interface, "coating efficiency" (CE) is introduced and scaled the cumulative percentage coating (CPC) to get predictable control over drug release (DR). Subsequently, the granules containing ASP are converted to spherules and then to Ethyl cellulose (EC) Coated spherules (CS) by a novel bed coating during the rolling (BCDR) process. Among spherules, one with 0.35 mm than 0.71 mm shows required properties. The CS has a low 1200 angle by Optical Microscopy (OM), smooth surface without cracks by scanning electron microscopy (SEM), and better flow properties (Angle of repose 29.69 ± 0.780, Carr's index 6.73 ± 2.24%, Hausner's Ratio 1.07 ± 0.03) than granules and spherules. Once certain structure-dependent control over release is attained (EC coated spherules shows 10% reduction in burst release (BR) than uncoated spherules showing a release of 80-91%) the predictability is achieved and Design of space (DOS) by DOE (CE-70.14%and CPC-200% and DR-61.54%) is established. The results of DOE to experimentally validated results were within 20% deviation. The aspirin is changing its crystal structure by powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) from Form-I to Form-II showing polymorphism inside the drug reservoir with respect to the process. This CE and CPC approach in DOE can be used for delivery system design of other labile drugs similar to aspirin in emergency situations.