Limits...
Utility of certain nucleophilic aromatic substitution reactions for the assay of pregabalin in capsules.

Walash MI, Belal FF, El-Enany NM, El-Maghrabey MH - Chem Cent J (2011)

Bottom Line: The developed methods were successfully applied to the analysis of the drug in its commercial capsules.Statistical analysis of the results revealed good agreement with those given by the comparison method.Proposals of the reaction pathways were postulated.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Analytical Chemistry, Faculty of Pharmacy, University of Mansoura, 35516, Mansoura, Egypt. nelenany1@yahoo.com.

ABSTRACT

Background: Pregabalin (PG) is an anticonvulsant, analgesic and anxiolytic drug. A survey of the literature reveals that all the reported spectrophotometric methods are either don't offer high sensitivity, need tedious extraction procedures, recommend the measurement of absorbance in the near UV region where interference most probably occurs and/or use non specific reagent that don't offer suitable linearity range.

Results: Two new sensitive and simple spectrophotometric methods were developed for determination of pregabalin (PG) in capsules. Method (I) is based on the reaction of PG with 1,2-naphthoquinone-4-sulphonate sodium (NQS), yielding an orange colored product that was measured at 473 nm. Method (II) is based on the reaction of the drug with 2,4-dinitrofluorobenzene (DNFB) producing a yellow product measured at 373 nm. The different experimental parameters affecting the development and stability of the reaction product in methods (I) and (II) were carefully studied and optimized. The absorbance-concentration plots were rectilinear over the concentration ranges of 2-25 and 0.5-8 μg mL-1 for methods (I) and (II) respectively. The lower detection limits (LOD) were 0.15 and 0.13 μg mL-1 and the lower quantitation limits (LOQ) were 0.46 and 0.4 μg mL-1 for methods (I) and (II) respectively.

Conclusion: The developed methods were successfully applied to the analysis of the drug in its commercial capsules. The mean percentage recoveries of PG in its capsule were 99.11 ± 0.98 and 100.11 ± 1.2 (n = 3). Statistical analysis of the results revealed good agreement with those given by the comparison method. Proposals of the reaction pathways were postulated.

No MeSH data available.


Effect of the heating time on the on the absorbance of the reactions products of PG with NQS or DNFB.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3141622&req=5

Figure 7: Effect of the heating time on the on the absorbance of the reactions products of PG with NQS or DNFB.

Mentions: The effect of heating times on the formation of the reactions products were investigated at different time intervals. The results revealed that, for Method I, complete reaction was achieved within 10 min and further increase in the reaction time did not affect the absorbance intensity (Figure 7). Regarding Method II, the reaction went to completion within 20 min, and longer reaction times up to 25 min did not affect the absorbance intensity. On the other hand, heating for 30 min resulted in slight decrease in absorbance intensity. So that, 20 min was selected as the optimum reaction time for Method II (Figure 7).


Utility of certain nucleophilic aromatic substitution reactions for the assay of pregabalin in capsules.

Walash MI, Belal FF, El-Enany NM, El-Maghrabey MH - Chem Cent J (2011)

Effect of the heating time on the on the absorbance of the reactions products of PG with NQS or DNFB.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3141622&req=5

Figure 7: Effect of the heating time on the on the absorbance of the reactions products of PG with NQS or DNFB.
Mentions: The effect of heating times on the formation of the reactions products were investigated at different time intervals. The results revealed that, for Method I, complete reaction was achieved within 10 min and further increase in the reaction time did not affect the absorbance intensity (Figure 7). Regarding Method II, the reaction went to completion within 20 min, and longer reaction times up to 25 min did not affect the absorbance intensity. On the other hand, heating for 30 min resulted in slight decrease in absorbance intensity. So that, 20 min was selected as the optimum reaction time for Method II (Figure 7).

Bottom Line: The developed methods were successfully applied to the analysis of the drug in its commercial capsules.Statistical analysis of the results revealed good agreement with those given by the comparison method.Proposals of the reaction pathways were postulated.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Analytical Chemistry, Faculty of Pharmacy, University of Mansoura, 35516, Mansoura, Egypt. nelenany1@yahoo.com.

ABSTRACT

Background: Pregabalin (PG) is an anticonvulsant, analgesic and anxiolytic drug. A survey of the literature reveals that all the reported spectrophotometric methods are either don't offer high sensitivity, need tedious extraction procedures, recommend the measurement of absorbance in the near UV region where interference most probably occurs and/or use non specific reagent that don't offer suitable linearity range.

Results: Two new sensitive and simple spectrophotometric methods were developed for determination of pregabalin (PG) in capsules. Method (I) is based on the reaction of PG with 1,2-naphthoquinone-4-sulphonate sodium (NQS), yielding an orange colored product that was measured at 473 nm. Method (II) is based on the reaction of the drug with 2,4-dinitrofluorobenzene (DNFB) producing a yellow product measured at 373 nm. The different experimental parameters affecting the development and stability of the reaction product in methods (I) and (II) were carefully studied and optimized. The absorbance-concentration plots were rectilinear over the concentration ranges of 2-25 and 0.5-8 μg mL-1 for methods (I) and (II) respectively. The lower detection limits (LOD) were 0.15 and 0.13 μg mL-1 and the lower quantitation limits (LOQ) were 0.46 and 0.4 μg mL-1 for methods (I) and (II) respectively.

Conclusion: The developed methods were successfully applied to the analysis of the drug in its commercial capsules. The mean percentage recoveries of PG in its capsule were 99.11 ± 0.98 and 100.11 ± 1.2 (n = 3). Statistical analysis of the results revealed good agreement with those given by the comparison method. Proposals of the reaction pathways were postulated.

No MeSH data available.