UV Spectrophotometric Estimation of Acipimox in Bulk and Capsule Dosage Form

A new simple, rapid, accurate, sensitive and precise spectrophotometric method in ultra violet region has been developed for determination of acipimox (ACX) in bulk and capsule dosage form. Acipimox exhibited maximum absorbance at 231 nm with apparent molar absorptivity of 1.5104 × 10 in distilled water. Beer's law was found to be obeyed in the concentration range 1-10 μg mL. Correlation coefficient was found to be 0.9998. The developed method was validated respect to linearity, precision, accuracy. The proposed method is useful for the routine estimation of ACX in bulk and capsule dosage form.


Introduction
Acipimox, chemically 5-methylpyrazine carboxylic acid 4-oxide (Figure 1), is a nicotinic acid analogue which is an antilipolytic drug used in the management of different forms of hyperlipidaemia [1][2][3] .Literature survey reveals that the drug can be estimated only by HPLC 4 and no spectrophotometric methods have been reported.The present study describes a simple, sensitive, accurate and precise spectrophotometric method for estimation of ACX in bulk and capsule formulation.UV analysis of ACX was performed in distilled water.The spectrum was recorded from 200 nm to 400 nm.The quantitative analysis was carried out at 231 nm.The method was validated and applied for the determination of ACX in capsule dosage form.

Experimental
The spectrophotometric measurements were carried out using Elico UV/Visible double beam spectrophotometer SL-164 with 1 cm matched quartz cells.

Reagents
ACX was tested for purity by measuring its melting point and IR spectra and no impurities were found.Doubly distilled water of analytical grade was used.A pharmaceutical preparation of ACX was obtained from local pharmacy.

Standard solutions
Standard stock solution of ACX (1000 µg mL -1 ) was prepared in distilled water.It was further diluted to obtain 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 µg mL -1 with distilled water.The absorbance was measured at 231 nm against distilled water as blank.The calibration curve was plotted in the concentration range of 1 to 10 µg mL -1 of ACX in distilled water.

Sample solutions
Twenty capsules containing ACX were weighed accurately and emptied.The powder equivalent to 100 mg ACX was dissolved in 20 mL of distilled water, sonicated for 15 minutes and filtered through Whatman No. 41 filter paper.The residues were washed thoroughly with distilled water and further diluted with distilled water to 5 µg mL -1 concentrations and the absorbance measured at 231 nm against distilled water as a blank.

Results and Discussion
The UV spectrum of standard solutions of ACX in distilled water was illustrated in Figure 2. The optical characteristics such as Beer's law limit 5 , molar absoptivity, Sandell's sensitivity 6 , slope and intercept are summarized in Table 1.The assay and precision studies results for capsules containing ACX are shown in Table 2.

Validation
The assay of ACX was validated with respect to stability, linearity, precision and accuracy.

Stability
The standard stock solutions of ACX were stored, in two different conditions, at +4 0 C and at ambient temperature for one month.During this period, the solutions were analyzed with UV spectrophotometric method, the spectrum was compared with the spectrum of daily prepared standard solution and no difference was obtained between them.It is decided that ACX is highly stable in the mentioned conditions.

Linearity and range
In developed UV method, calibration curve was linear in the range from 1 to 10 µg mL -1 of ACX.

Inter-day precision
This was done by analyzing formulation by same analyst for six days subsequently.The % RSD values are shown in Table 2.

Intra-day precision
This was done by analyzing formulation in same day for six times of individual preparation and observation.The % RSD and data are shown in Table 2.

Accuracy
Recovery studies were performed to judge the accuracy of the method.Recovery studies were carried out by adding a known quantity of pure drug to a pre-analyzed formulations and the proposed method was followed.From the amount of drug found, percentage recovery was calculated.The results of analysis and recovery studies are given in Table 3.

Conclusion
In this study a simple and rapid UV spectrophotometric method for the determination of ACX in bulk and pharmaceutical formulation has been developed and validated.

Figure 2 .
Figure 2. UV spectrum of Acipimox in distilled water.

Table 1 .
Optical characteristics of proposed method.

Table 2 .
Assay results and precision studies.