INTRODUCTION:

Milnacipran¹ (MCP) is a nor-epinephrine and serotonin reuptake inhibitor, with a (Amino-methyl)-N, N-diethyl-1-phenyl cyclopropane carboxamide. It is official in Martindale- The extra pharmacopoeia. It is an Anti-Depressant drug² that acts by inhibiting a nor-epinephrine and serotonin reuptake in a 3:1 ratio; in practical use this means a balanced (equal) action upon both transmitters. The serotonin reuptake inhibition is likely to improve depression, while the nor-epinephrine reuptake inhibition probably improves chronic pain. Literature survey reveals many Chromatographic methods^3-7 for the determination of Milnacipran in biological fluids and in combination with other antidepressant and very few Spectrophotometric methods and no visible method was reported. Therefore the need for fast, low cost and selective method is obvious especially for routine quality control analysis of pharmaceutical formulation.

EXPERIMENTAL:

INSTRUMENT:

Elico double beam Ultra Violet –Visible double beam Spectrophotometer SL-244 with 1cm matched quartz cells was used for all spectral measurements.

Reagents:

All chemicals used were of analytical reagent grade

· Bromocresol Green 0.5% w/v- Weigh 0.125 gm of dye sample and dissolve in 10ml of water and make up to 25ml and Filter it using filter paper.

· Preparation of Phosphate Buffer pH 3.6: Dissolve 0 .900gm of anhydrous di sodium hydrogen phosphate and 1.298 gm of citric- acid monohydrate in sufficient water to produce 1000ml.

· Chloroform AR grade.

PROCEDURE:

Standard stock solution:

A standard stock solution containing 1 mg/ml was prepared by dissolving 100mg of Milnacipran in 100ml of distilled water. From this, a working standard solution containing 500µg/ml was prepared with distilled water.

ASSAY PROCEDURE:

Aliquots of standard drug solution of MCP containing 0.1-1.0 ml (500 mcg/ml) are taken and transferred into series of graduated test tubes. To each test tube 1 ml of 0.5% w/v Bromocresol Green and 2 ml of Phosphate buffer pH 3.6 were added. Reaction mixture was shaken gently for 5 min. Then 10ml of chloroform was added to each of them. The contents are shaken thoroughly for 5 min and allowed to stand for 15 minutes, so as to separate the aqueous and chloroform layer. Coloured chloroform layer was separated out and absorbance was measured at 412 nm against reagent blank. Calibration curve was prepared from absorbance values so obtained.

Preparation of sample solution:

Capsules containing Milnacipran were successfully analyzed by the proposed methods. Ten capsules of Milnacipran (Milborn 25mg, Hetero Drug) were accurately weighed and powdered. Capsule powder equivalent to 100mg of Milnacipran was dissolved in 100ml of distilled water and filtered and washed with distilled water, the filtrate and washings were combined and the final volume was made to 100ml with distilled water. The solution was suitable diluted and analyzed as given under the assay procedure for bulk samples. The results are represented in table 2. None of the excipients usually employed in the formulation of capsules interfered in the analysis of Milnacipran, by the proposed method.

Recovery Studies:

To ensure the accuracy and reproducibility of the results obtained, adding known amounts of pure drug to the previously analyzed formulated samples and these samples were reanalyzed by the proposed method and also performed recovery experiments. The percentage recoveries thus obtained were given in Table 2.

RESULTS AND DISCUSSIONS:

In the present work a method has been developed for the estimation of Milnacipran from capsule formulation. The developed method was based on formation of chloroform extractable colored complex with Bromo Cresol Green. The condition required for formation of colored complex was optimized. Statistical analysis was carried out and the results were satisfactory. Relative standard deviation values were low that indicates the reproducibility of the proposed methods. Recovery studies were close to 100% that indicates the accuracy and precision of the proposed methods. The optical characteristics such as absorption maxima, beer’s law limit, molor-absorptivity and sand ell’s sensitivity are presented in table 1. The regression analysis using the method of least square was made for slope (m), intercept (b) and correlation obtained from different concentrations and the results are summarized in table 1.

In conclusion, the proposed method are simple, economical, sensitive, precise reliable and reproducible for the routine estimation of Milnacipran in bulk as well as in capsule formulation.

TABLE 1: OPTICAL CHARACTERSTICS AND PRECISION DATA

Parameter	Proposed method
λmax( nm)	412
Beers law limit	50-500 mcg/ml
Molar absorbtivity (micrograms/cm2/0.001 Absorbance unit)	1.759x 10³
Sand ell’s sensitivity (micrograms/cm²/0.001 Absorbance unit)	0.174
Regression equation y Slope (m) Intercept©	0.0001 0.66
Correlation coefficient	0.9985
Precision( % relative standard deviation)	0.10
Standard error of estimate	0.0416

*y = mx +c where X is the concentration in micrograms/ml and Y is absorbance unit

TABLE 2 : ASSAY OF MILNACIPRAN IN CAPSULES FORMULATIONS.

Capsule Formulation	Labeled Amount (Mg)	Amount obtained(mg)* By proposed method	%Recovery By the Proposed Method **
01	25	24.79	99.16
02	25	24.88	99.54
03	25	25.57	102.3

*Average of three determinations **After spiking the sample

ACKNOWLEDGEMENTS:

The authors are grateful to Hetero Drugs, Hyderabad for the supply of Milnacipran as a gift sample and to the SSJ College of Pharmacy, Hyderabad, for providing the necessary facilities to carry out the research work.

REFERENCES:

1. The Merck Index, 14th edition maryadele J o neil editor, 2006, pg 6194

2. Martindale-The Complete Drug Reference, 34^th edited by sean c. sweetman pg.307.3.

3. Moret C, Charveron M, Finberg JP, Couzinier JP, Briley M (1985). "Biochemical profile of Milnacipran (F 2207), 1-phenyl-1-diethyl-aminocarbonyl-2-aminomethyl-cyclopropane (Z) hydrochloride, a potential fourth generation antidepressant drug". Neuropharmacology 24 (12): 1211–9. Doi:10.1016/0028-3908(85)90157-1. PMID 3005901.

4. Briley M, Prost JF, Moret C (1996). "Preclinical pharmacology of Milnacipran". International clinical psychopharmacology 11 Suppl 4: 9–14. PMID 8923122.

5. USP 25–NF 20 (United States Pharmacopeial Convention, Rockville, MD, 2002), p. 2256.

6. Development And Vali.Dation Of RpHplc Method For Determination Of Milnacipran Hydrochloride In Pharmaceutical Formulations PRITI J. MEHTA*, DEEPAK M. KHATRI www.ijppsjournal.com/Vol2Suppl2/568.pdf

7. Development And Validation Of UV Spectrophotometric Method For Determination Of Milnacipran In Bulk And Pharmaceutical Dosage Form Punit B Parejiya, Pragna K Shelat, Rakshit C Patel, Bhavesh S Barot, Arun K Shukla Eurasian Journal Of Analytical Chemistry, Vol 6, No 1 (2011)

Received on 29.05.2011 Modified on 04.06.2011

Research J. Pharm. and Tech. 4(8): August 2011; Page 1250-1251