Purpose:
The official
assay methods for most antiretroviral drugs are limited
by cost and unavailability of good test equipment in
several developing countries. Therefore, this study
investigates the use of charge transfer complexation in
the spectrophotometric assay of stavudine as an
alternative method to conventional methods.
Methods:
Charge transfer
complex formation between stavudine (n-donor) and
chloranilic acid (p-acceptor) in 1,4-dioxan using a
spectrophotometer was employed. Thermodynamic parameters
of the complex formed were determined. The proposed
method was employed in the analysis of commercially
available stavudine dosage form.
Results:
The wavelength of maximum absorption (λmax)
of the complex was at 526 nm compared to 457 nm for
p-acceptor alone. Beer’s law was obeyed in the range of
5 - 40 mg % while the stoichiometry of the complex was
found to be 2:1. The complex formed was still stable 24
h later. Its formation was spontaneous with a ΔHo
of -3.78×103 J/mol. The standard
entropy change was from 12.18 ± 0.78 to 11.08 ± 1.23
cal/deg/mol over the temperature range of 30 - 60 oC
while molar absorptivity decreased from 2.45×105
to 1.2×105 over the same temperature
range. The assay result of the standard stavudine
solution was of high accuracy with a recovery value of
99.85 ± 1.95 %.
Conclusion:
The proposed method is reliable and reproducible and
should be suitable for the quality control of stavudine
in bulk and dosage forms.
Keywords:
Assay, Charge transfer,
Stavudine, Spectrophotometric analysis, Chloranilic
acid, Thermodynamic.
