INTRODUCTION:

Citalopram (CIT), a selective serotonin reuptake inhibitor, is one of the most widely used antidepressants for the treatment of anxiety, obessional and control disorders¹. This selective serotonin reuptake inhibitor shares with setaline a lower propensity to cause drug interactions. Its t_1/2 is 33hrs. and no active metabolite is known. However, few deaths due to overdose of citalopram are on record, because of which it is advised to be avoided in patients likely to attempt suicide². Although citalopram has gained wide acceptance in the treatment of depression and anxiety disorders, its use during pregnancy and lactation has been poorly characterized³. Citalopram is a drug with a clinical profile similar to fluoxetine. It offers as the other SSRI members an efficient alternative treatment of depression to the TCAs. In addition, it is useful in treating alcoholism, pain and pathological crying and laughing. Citalopram is readily absorbed from the GI tract after ingestion, reaching peak plasma concentration after 2-4hrs. Its protein binding is low. Metabolism occurs with demethylation, deamination and oxidation steps into inactive metabolites⁴. There are very few methods described in literature for the determination of citalopram. The drug has been determined in human plasma using HPLC-electrospray ionization mass spectrometry⁵. The drug and its metabolites can be determined in human plasma by LC-MS/MS⁶ and LC-fluoroscence detection⁷.

EXPERIMENT:

Chemicals and Solvents

HPLC grade methanol, HPLC grade acetonitrile, KH₂PO₄ phosphate buffer and H₃PO₄phosphate buffer pH 3.4 were used as mobile phase.

Pure sample of citalopram (Sun Pharmaceutical Ltd) and commercial samples of tablets containing the drug namely Citopam-20 (Sun Pharmaceutical Ltd) were employed in the study.

Chromatographic Conditions

A gradient HPLC system with YoungLin SP930D solvent delivery pump, a RP C18 Column (Inertsil C18, 250mm * 4.6 mm, 5μ), a UV dual wavelength detector YoungLin UV730D for HPLC was employed. Autochro-3000 was used as a software for running HPLC system that is 32 bit and fully compatible with MS Window XP.

All the solutions was filtered through 0.2 μm membrane filter

Estimation of Citalpram

For Citalopram: 100mg of citalopram was accurately weighed and transferred to a 100ml volumetric flask and was diluted with methanol. (Stock A). Aliquots of Stock A was further diluted to get concentration of 10, 20, 30, 40 and 50 μg/ml.

To establish the linearity of analytical method, a series of dilution ranging from 10-50 μg/ml were prepared. All the solutions was filtered through 0.2 μm membrane filter and injected, chromatograms was recorded and it was repeated for six times. A calibration graph was plotted between the mean peak area vs. respective concentration and regression equation was derived. The flow rate was kept 1.35ml/min. Each of the dilutions was injected 6 times into the column and the corresponding chromatograms were obtained.

Estimation of the Drug in Tablet Dosage Form

Commercial brand of Citopam-20 (Sun Pharmaceutical Ltd) were employed in the study. Twenty tablets were accurately weighed and average weight was determined. Tablets were powdered and powder equivalent to 100mg per tablet of citalopram was taken accurately weighed and transferred into two respective volumetric flask (100ml). This was dissolved in methanol and sonicate for 3min. The volume was made up to mark and filtered through Whatmann’s filter paper. Filter was further diluted with to get the final dilution. The response of final dilutions were observed at selected wavelength and the concentration were obtained from equation. The procedure was repeated for three times. The mean peak area of the drug was calculated and the drug content in the tablets was quantified using regression equation obtained for the pure sample.

RESULT AND DISCUSSION:

The present study was aimed at developing a sensitive, precise and accurate HPLC method for the analysis of Citalopram in pharmaceutical dosage form. For this, methanol, acetonitrile, KH₂PO₄ phosphate buffer and H₃PO₄phosphate buffer pH 3.4 (55:40:5) (v/v/v) portion was found to be most suitable mobile phase as the peaks obtained were sharp, better resolved and almost free from tailing. The retention time for Glipizide was 3.741min. The calibration range was found to be in the range of 10-50 μg/ml (r²= 0.998) for citalopram. y=13994x+9448 where y= peak area, m= slope, x=concentration, c= intercept. The drug content in the tablets was quantified using the proposed method of analysis. The mean amount of citalopram obtained in tablet dosage form was found to be 99.134%. This reveals that the method is quite precise. The absence of additional peaks in the chromatogram indicated non interference of the common excipients used in the tablets.

It can be concluded that the proposed HPLC method is sensitive and reproducible for the analysis of Citalopram in pharmaceutical dosage form in a short analysis time. The method was duly validated by evaluation of the required parameters.

Table 1. Calibration of the Proposed Method

Concentration of Citalopram μg/ml.	Peak area
10	147420.83
20	299636.83
30	438582.33
40	574719.66
50	695397.00

Table 2: Regression Characters of The Proposed HPLC Method

Parameters	Value
Slope	13994
Intercept	9448
Correlation coefficient (r)	0.998

Table 3: Day to Day and Analyst to Analyst Precision of the Proposed Method

Concentration of Citalopram μg/ml.	Observed concentration of Citalopram μg/ml.
	Day to Day		Analyst to Analyst
	Mean (n=3)	RSD (%)	Mean (n=3)	RSD (%)
20	20.683	0.072	20.53	0.647
30	30.61	0.130	30.58	0.130

Table 4: Assay of Citalopram in Tablet Dosage Form

Brand name of the Tablet	Labelled amount of drug (mg)	Mean amount found by the proposed method	Mean % labeled amount
Citopam-20	20	20.56	102.80

Figure 1: A model chromatogram of Citalopram and Internal Standard (Caffiene)

REFERENCE:

1. Jeong-Wook Kwon, Kwin L Armburst, Environ Toxicol Chem. 2005, 24(7), 1618.

2. Tripathi KD, Essentials of Medical Pharmacology, 2003, 5, 412.

3. Heikkinan Tuija MD, Ekblad Ulla MD, Pentti Kero MD, Ekblad Satu RN and Laine Kari MD, Clinical Pharmacology and Therapeutics, 2002, 72, 184.

4. Holenz, Diaz and Buschmann, Drugs and Drugs in Development, 2007, 1, 201.

5. He Juan, Zhou Zhiling and Li Huande simultaneous determination of fluoxenthine, citalopram, paroxetine, venlafaxine in plasma by HPLC-electrospray ionization mass spectrometry. Journal of Chromatography B,2005, 820 (1), 33

6. Jiang Tao, Roug Zhengxima, Peng Liang, Chen Bing, Xie Yifan, Chen Congying, Sun Jing simultaneous determination of citalopram and its metabolite in human plasma by LC-MS/MS applied to pharmacokinetic study, Journal of Chromatography B, 2010, 878, 615.

7. Bagheri Habib, Khalilian Faezeh, Babanezhad Esmail, Es-Gaghi Ali, Rouini Mohammad-Reza, modified solvent microextraction with back extraction combined of citalopram with LC-fluoroscence detection for the determination of citalopram in human plasma, Analytical Chemistry ACTA, 2008, 211.

Received on 22.02.2011 Modified on 20.03.2011

Research J. Pharm. and Tech. 4(12): Dec. 2011; Page 1807-1808