A Validated Non-Aqueous Potentiometric Titration Method for Quantitative Determination of Alprazolam from Pharmaceutical Preparation

Rele Rajan V.* , Tiwatane Prathamesh P.

Department of Chemistry, D.G. Ruparel College, Mahim, Mumbai 400 016.

*Corresponding Author E-mail: drvinraj@gmail.com

ABSTRACT:

A simple precise, rapid accurate and sensitive non-aqueous potentiometric titration method was developed for quantitative determination of alprazolam from pharmaceutical dosage form. The titration was carried out using standardized 0.1 N perchloric acid. The proposed method was found to be precise with % RSD <1 (n = 6). The method showed strict linearity (r² > 0.9999 ) between 20 % to 100 % of 0.100 mg of drug substance weight. The percentage recovery of alprazolam in the optimized method was between 100.0 to 100.416 %. The method is also found to be rugged when checked by different analysts and using different lots of reagents and different makes of titrators.

KEYWORDS: Alprazolam, Perchloric acid, Potassium hydrogen phthalate, Glacial acetic acid.

INTRODUCTION

Alprazolam is chemically 8-chloro-1-methyl-6-phenyl-4H-(1,2,4) triazolo (4,3a)1,4-benzodiazepine, which is a short acting anxiolytic drug. It also possesses sedative, hypnotic, anticonvulsant, amnesic and skeletal muscle relaxant property. Alprazolam is a short-acting drug of the benzodiazepine. It is used to treat moderate to severe anxiety disorders and panic attacks and is used as an adjunctive treatment for anxiety associated with moderate depression.

Alprazolam may be habit-forming, and long-term use and abuse may cause a physical dependence to develop along with withdrawal reactions during abrupt or rapid discontinuation. Although the side-effect profile of alprazolam may occur in some patients. Some side-effects may disappear with continued treatment. If signs of an allergic reaction occur - such as hives; difficulty breathing; swelling of face, lips, tongue, or throat. Literature survey reveals the HPLC [1] and spectrophotometric [2-6] methods for the estimation of alprazolam. Simple, rapid and reliable no aqueous titration method is developed for the determination of alprazolam. This method can be used for the routine analysis. In the proposed methods optimization and validation of this method are reported.

Structure of alprazolam

EXPERIMENTAL:

Instrumentation

An potentiometric titrator was used ( Lab- India-Auto titrator ) for assay method development and validation.

A Shimadzu analytical balance with 0.01 mg was used.

Reagents and chemical

Reference standard of alprazolam was obtained from reputed firm with certificate of analysis.

Potassium hydrogen phthalate , perchloric acid and glacial acetic acid of A. R. grade were used.

General procedure

Standardization of 0.1 N perchloric acid

About 0.350 mg of potassium hydrogen phthalate (previously powdered lightly, dried at 120^oC for 2 hours) was weighed accurately into clean and dry titration jar. It was dissolved in 50 ml of glacial acetic acid. About 0.1 ml of crystal violet solution ( 0.5 % w/v in anhydrous glacial acetic acid ) was added. It was titrated with 0.1 N perchloric acid using auto titrator. Blank determination was performed out for necessary correction. The titration was performed in duplicate.

One ml of 0.1 N HClO₄ is equivalent to 0.2042 gm of potassium hydrogen phthalate (C₈H₅KO₄)

Normality of perchloric acid = --------------------------

B.R. x 0.2042

Where,

W is weight of potassium hydrogen phthalate in g.

B.R. is burette reading in ml.

Quantitative determination of alprazolam

About 0.100 g. of alprazolam test sample was weighted accurately into a clean and dried titration jar. It was dissolved in 35 ml. of anhydrous glacial acetic acid and 15 ml of 5% (w/v) mercuric acetate.

It was titrated with 0.1 N perchloric acid potentiometrically.

Blank determination was also carried out for necessary correction.

One ml of 1 N perchloric acid is equivalent to 0.07719 g. of alprazolam

% (Percentage) Alprazolam on the dried basis was calculated as below.

B.R. x N x 0.07719 x 100

% Assay = ------------------------------------------

Where,

B.R. is burette reading in ml at the potentiometric end point.

N is actual normality of 0.1 N perchloric acid.

W is weight of the sample taken in g.

RESULT AND DISCUSSION:

Determination of alprazolam

The objective of this work was to determine accurately the content of alprazolam. The assay of alprozolam (on the dried basis) of various batches of alprazolam test sample was analyzed using the above method. It was in the range of 100.0 % to 100.416 %.

Analytical method validation

The method precision was checked after analyzing six different preparations of homogeneous test sample of alprazolam. The % RSD of results obtained was found to be 0.6743. It confirms good precision of the method. The results are presented in table 1.

Table no. 1 : Method of precision

Sr.no	Weight of alprazolam	Burette reading in ml	Normality of perchloric acid	% assay
1	0.100	13.0	0.09990	100.246
2	0.100	13.02	0.09990	100.400
3	0.100	13.0	0.09990	100.246
4	0.100	12.98	0.09990	100.09
5	0.100	13.0	0.09990	100.246
6	0.100	13.0	0.09990	100.246
			Mean	100.2457
			Std. Deviation	0.098032
			RSD	0.09779

Table no.2 : Linearity

Sr. No.	Weight of alprazolam	Burette reading	Normality of Perchloric acid	% assay
1	0.020	2.61	0.09990	100.63
2	0.040	5.22	0.09990	100.63
3	0.060	7.80	0.09990	100.24
4	0.080	10.41	0.09990	100.34
5	0.100	13.0	0.09990	100.24
			Mean	100.416
			Std. Deviation	0.199575
			RSD	0.1986

The potentiometric titration was conducted once at each level. Linearity curve Figure no .1 was drawn by plotting test sample weight in gram on x axis and titre values on y axis.

Fig. no.1: Linearity curve

The values of correlation coefficient, slope and intercept are given in table 3.

Table no.3: Regression values

Parameter	Values
Slope	130.85
Intercept	-0.023
Coefficient of co-relation	0.9999

Accuracy and recovery

Accuracy was determined at five different levels i.e., 20 % ,40 % ,60 % ,80 % and 100 % of the nominal concentration. (0.100 g.) The titration was conducted in triplicate at each level and the titre value was recorded. The tire value obtained in linearity study was considered as true value during the calculation of percentage ( %) recovery. The percentage recovery is calculated using following equation.

Titre value X 100

Percentage recovery = ---------------------------

True titre value

The percentage range recovery of alprazolam was in 100.0 to 100.416 %. It confirms the accuracy of the proposed method. (Table 4).

Table no 4 : accuracy and precision

Level no.	Weight of alprazolam added	Weight of alprazolam found	% assay	Mean % assay
1	0.020	0.0200	100.0	100.00
	0.020	0.0201	100.5
	0.020	0.0199	99.5
2	0.040	0.400	100.0	100.4167
	0.040	0.0402	100.5
	0.040	0.0403	100.75
3	0.060	0.0600	100.0	100.0333
	0.060	0.0601	100.1
	0.060	0.0600	100.0
4	0.080	0.0800	100.0	100.04
	0.080	0.0801	100.12
	0.080	0.0800	100.0
5	0.100	0.1020	102.0	101.00
	0.100	0.1010	101.0
	0.100	0.1000	100.0

RUGGEDNESS:

The ruggedness of the method is defined as degree of reproducibility of results obtained by analysis of alprazolam sample under variety of normal test conditions such as different laboratories, different analysts and different lots of reagents. Quantitative determination of alprazolam was conducted potentiometrically on one laboratory. It was again tested in another laboratory using different instrument by different analyst. The assays obtained in two different laboratories were well in agreement. It proved ruggedness of the proposed method.

CONCLUSION:

The proposed method of non-aqueous potentiometric titration was found to be precise, accurate and rugged. The values of percentage recovery and standard deviation showed sensitivity. The method was completely validated. It showed satisfactory data for all the parameters of validation. Hence it can be applied for routine quality control application.

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