The present study describes a simple stability-indicating reversed-phase HPLC assay
for pentoxifylline in its pharmaceutical dosage forms. Separation of the drug and the
degradation products، under stress conditions was successfully achieved on a C
18 column
utilizing water: MeOH (60:40 v/v)، pumped at a flow rate of 1 ml min-1 with UV detection
at 272 nm. The retention time of pentoxifylline was about 14 min. The method was
satisfactorily validated with respect to linearity، precision، accuracy and selectivity. The
response was linear in the range of 0.6-3.5 μg/ml with R2 0.994. The method was accurate
(recovery 100.1%) and precise (RSD < 2%). Detection and quantification limit were 0.2
μg/ml and 0.4 μg/ml respectively. The suggested method was successfully applied for the
analysis of pentoxifylline in extended release tablets available in Syrian market.
The objective of this study was to study and to analyze caffeine release from gel and
emulgel prepared from carbopol. The properties of the preparations were determined (e.g.
visual inspection, pH test, spreadability and in vitro release). The mech
anisms of caffeine
release were analyzed according to zero and first orders, and to Higuchi and Korsmeyer-
Peppas models. Results were analyzed statistically using student t-test.
The gels were transparent while emulgels were creamy, white and smooth. pH values
were suitable for dermal application and spreadability was not changed in both cases. On
the other hand, accumulated released amount of caffeine was decreased from emulgel in
comparison with the gel. The release pattern was in accordance with Higuchi equation and
n value referred that the diffusion was the main mechanism of release from the gel while
the relaxation and the erosion contributed importantly in the release of suspended caffeine
from emulgel.
The objective of this study was to prepare acceptable carbopol gels and to evaluate
the factors influencing the spreadability and release properties of a model hydrophilic
compound (caffeine). Results were analyzed statistically using student t-tes
t. The gels
were transparent at 1 and at 2% caffeine (with alcohol). Spreadability was decreased when
carbopol was increased and when caffeine quantity was changed (except at 2% carbopol).
Spreadability was affected statistically with change of cosolvent. Released caffeine
quantity (%) was increased with decreasing of carbopol quantity and increasing of caffeine
quantity introduced in the formula. Total caffeine quantity (%) was decreased with alcohol
presence. Caffeine release followed Higuchi pattern, e.g. diffusion was the principal
mechanism of caffeine release from these formulas.
This paper presents a developed HPLC method for the determination of
caffeine and theobromine in different black and green tea infusion samples,
using different infusion methods, such as infusion with and without boiling,
repeated and continuous i
nfusion. A mixture of double-distilled water and
methanol (60:40 v/v), was used as a mobile phase. In this condition, the
retention time for theobromine was three minutes and for caffeine five minutes.
