Purpose:
To develop and characterize bilayer tablet formulations
of tramadol HCl (TmH) and acetaminophen (AAP)
microparticles.
Methods:
Coacervation via temperature change was the encapsulated
method used for the preparation of the microparticles,
with ethyl cellulose (EC) of medium viscosity as the
polymer for extending drug release. The microparticles
of the two drugs were prepared separately and then
compressed into bilayer tablets. The physicochemical
compatibility and stability of the tablets were
determined by Fourier transform infrared spectroscopy (FTIR),
x-ray diffractometry (XRD),
differential
scanning calorimetry (DSC)
and thermogravimetric
analysis (TGA) while their mechanism and pattern of drug
release were assessed by applying Higuchi, Zero order,
First order and Korsmeyer-Peppas kinetic models. Bilayer
tablets were subjected to accelerated stability studies
for three months.
Results:
FTIR, XRD, DSC and TGA data for the formulations
indicate good compatibility and stability. Furthermore,
accelerated stability studies confirmed the stability of
the formulations. Controlled drug release from the
microparticles and bilayer tablets was observed for 8 h
and 12 h, respectively. The Higuchi model produced the
best fit, with regard to release profile, for both
drugs, with correlation coefficient (R2) of
0.966 and 0.960 for AAP and TmH, respectively.
Conclusion:
Microencapsulated TmH and AAP can be developed into
suitable bilayer tablets that are stable and capable of
releasing the drugs over 12 h.
Keywords:
Acetaminophen; Tramadol; Ethyl cellulose;
Microparticles; Bilayer tablets; Kinetic models.
