The analytical solution for drug delivery system with nonhomogeneous moving boundary condition

2017 ◽  
Author(s):  
Muhamad Hakimi Saudi ◽  
Shalela Mohd Mahali ◽  
Fatimah Noor Harun
Author(s):  
Minghan Xu ◽  
Saad Akhtar ◽  
Mahmoud A. Alzoubi ◽  
Agus P. Sasmito

Abstract Mathematical modeling of phase change process in porous media can help ensure the efficient design and operation of thermal energy storage and pipe freezing. Numerical methods generally require high computational power to be applicable in practice. Therefore, it is of great interest to develop accurate and reliable analytical frameworks. This study proposes a singular perturbation solution for a two-phase Stefan problem that describes outward solidification in a finite annular space. The problem solves cylindrical heat conduction equations for both solid and liquid phases, with consideration of a moving boundary condition. Perturbation method takes the advantages of small Stefan number as the perturbation parameter, which intrinsically occurs in porous media. Furthermore, a boundary-fixing technique is used to remove nonlinearity in the moving boundary condition. Two different time scales are separately expanded and evaluated to facilitate the construction of a composite asymptotic solution. The analytical solution is verified against a general numerical model using enthalpy method and local volume-averaged thermal properties. The results indicate that the temperature profile of both phases can be well modeled by singular perturbation theory. The analytical solution is found to have similar conclusions to the numerical analysis with much lesser computational cost.


Planta Medica ◽  
2015 ◽  
Vol 81 (16) ◽  
Author(s):  
AR Bilia ◽  
G Capecchi ◽  
MC Salvatici ◽  
B Isacchi ◽  
MC Bergonzi

Author(s):  
ShirishaG. Suddala ◽  
S. K. Sahoo ◽  
M. R. Yamsani

Objective: The objective of this research work was to develop and evaluate the floating– pulsatile drug delivery system (FPDDS) of meloxicam intended for Chrono pharmacotherapy of rheumatoid arthritis. Methods: The system consisting of drug containing core, coated with hydrophilic erodible polymer, which is responsible for a lag phase for pulsatile release, top cover buoyant layer was prepared with HPMC K4M and sodium bicarbonate, provides buoyancy to increase retention of the oral dosage form in the stomach. Meloxicam is a COX-2 inhibitor used to treat joint diseases such as osteoarthritis and rheumatoid arthritis. For rheumatoid arthritis Chrono pharmacotherapy has been recommended to ensure that the highest blood levels of the drug coincide with peak pain and stiffness. Result and discussion: The prepared tablets were characterized and found to exhibit satisfactory physico-chemical characteristics. Hence, the main objective of present work is to formulate FPDDS of meloxicam in order to achieve drug release after pre-determined lag phase. Developed formulations were evaluated for in vitro drug release studies, water uptake and erosion studies, floating behaviour and in vivo radiology studies. Results showed that a certain lag time before drug release which was due to the erosion of the hydrophilic erodible polymer. The lag time clearly depends on the type and amount of hydrophilic polymer which was applied on the inner cores. Floating time and floating lag time was controlled by quantity and composition of buoyant layer. In vivo radiology studies point out the capability of the system of longer residence time of the tablets in the gastric region and releasing the drug after a programmed lag time. Conclusion: The optimized formulation of the developed system provided a lag phase while showing the gastroretension followed by pulsatile drug release that would be beneficial for chronotherapy of rheumatoid arthritis and osteoarthritis.


Author(s):  
Syukri Y ◽  
Afetma D. W. ◽  
Sirin M. ◽  
Fajri R. ◽  
Ningrum A. D. K. ◽  
...  

This research aim to validation of a simple, rapid and accurate HPLC-UV method for the quantification of andrographolide isolated from Andrographis paniculata Ness in Self Nano Emulsifying Drug Delivery System (SNEDDS) formulation during the dissolution test. The assay was performed using a XTerra® MS C18 column (150 mm X 4.6 mm, five μm) with a mobile phase of methanol and water (70: 30), at 0.8 mL/min flow rate and UV detection of 229 nm. Simulation gastric fluid (SGF) and intestinal fluid (SIF) were prepared as dissolution medium. The validation parameter was conducted including the test on linearity, precision, accuracy, LOD, and LOQ. The result showed an excellent linearity with r = 0.999 and good selectivity for both medium dissolution. The method showed sufficient precision, with a relative standard deviation (RSD) smaller than % Horwitz. The accuracy reported as % recovery was found to be 102.61 and 101.17 % in each SGF and SIF dissolution medium. LOD and LOQ were found 0.46 and 1.40 in SGF medium, 0.87 and 2.64 in SIF medium. In conclusion, the HPLC method developed showed specificity and selectivity with linearity in the working range, good precision and accuracy and suitable for quantification andrographolide in SNEDDS formulation.


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