INTRODUCTION:

Cetirizine hydrochloride (CTZ) chemically is (±)-[2-[4-[(4-chlorophenyl) phenyl methyl]-1-piperazinyl] ethoxy] acetic acid hydrochloride^[1-4]. Cetirizine hydrochloride, a human metabolite of hydroxyzine, is an antihistamine; its principal effects are mediated via selective inhibition of peripheral H₁ receptors. CTZ competes with histamine for binding at H₁-receptor sites on the effector cell surface, resulting in suppression of histaminic edema, flare and pruritus. The antihistaminic activity of CTZ has been clearly documented in a variety of animal and human models.^[4-5]

Phenylephrine hydrochloride (PHE) chemically is (R)-1-(3-hydroxyphenyl)-2-methylaminoethanol Hydrochloride^[6-7]. PHE is a sympathomimetic with mainly direct effects on alpha-adrenergic receptors and weak beta-adrenergic activity. It causes vasoconstriction of the arterioles of the nasal mucosa and conjunctiva; activates the dilator muscle of the pupil to cause contraction; produces vasoconstriction of arterioles in the body and produces systemic arterial vasoconstriction. PHE is nasal decongestant its effectiveness as a decongestant stems from its vasoconstriction of nasal blood vessels, thereby decreasing blood flow to the sinusoidal vessels, leading to decreased mucosal edema.^[7]

The combination of PHE and CTZ have additive or synergistic role in cough and anti-allergic preparation, since both acts by attenuating the sign and symptoms of common cold and allergy^[8].

Literature reveals that many analytical methods are specified for the determination of PHE and CTZ as individual and combined dosage form with other combination of drugs and also in biofluid viz., UV-visible spectrophotometry^[9-11],

HPLC^[12-15], fluorometry^[16],HPTLC^[17-19] and ion-pair chromatographic method^[20]. The aim of this study was to develop simple,precise, accurate and convenient method for the simultaneous estimation of PHE and CTZ in combine dosage form.

HCl

Fig. No. 1:- Chemical Structure of Cetirizine hydrochloride.

Fig No 2: Chemical Structure of Phenylephrine hydrochloride

MATERIALS AND METHOD:

Instrument Used:

A Shimadzu UV/Vis-1800, double beam spectrophotometer with matching pair of 1 cm quartz cuvettes with a fixed slit width 2 nm was used for all spectral measurements.

Reagents and Solution:

Phenylephrine hydrochloride and Cetirizine hydrochloride were procured as a gift samples from Sun Pharma Pvt. Ltd., Vadodara, Gujarat. The commercial formulation of PHE and CTZ in the ratio1:1. Allercet-DC manufactured by Micro Labs Ltd, was purchased from local market. The solution of 0.1N HCL was prepared in double distilled water as per IP 1996 procedure.

Standard Stock Solution:

Standard stock solutions (100ug/ml) were prepared by separately dissolving 10 mg each of PHE and CTZ in 0.1 N HCL. Suitable aliquots of standard stock solutions were diluted with 0.1 N HCL to obtain solutions of PHE (10ug/ml) and CTZ (10ug/ml) and scanned in the spectrum mode against solvent blank over the range of 200 to 400 nm. The UV absorption overlain zero order spectrum of PHE and CTZ is depicted in fig.3. from the overlain spectra the wavelength selected for estimation of drugs were 272.8 nm and 230.83 λmax of PHE and CTZ respectively. From the overlain spectra the wavelengths selected for estimation of drugs were 230.0 nm (isobestic point) and 272.80 nm (λmax of phenylephrine hydrochloride).

Fig.1 Overlain spectra of PHE (10 ug/ml) and CTZ (10ug/ml)

Application of proposed method for the determination of PHE and CTZ in tablets:

Q-absorbance method uses the ratio of absorbances at two selected wavelengths,one at iso-absorptive point and other being the λmax one of the two drugs. The wavelengths selected for analysis were 230.0 nm and 272.80 nm. For analysis of both PHE and CTZ in tablets, twenty tablets were accurately weighed and finely powdered. An accurately weighed quantity of tablet powder equivalent to 10 mg was transferred to 100 ml volumetric flask and dissolved by sonication with sufficient quantity of methanol and volume was made upto mark with 0.1 N HCL. The solution was then filtered through whatmann filter paper No.41. The solution is expected to contain 100 ug/ml PHE and 100 ug/ml CTZ. One ml of this solution was transferred to a 10 ml volumetric flask and volume was made upto mark with 0.1 N HCL to obtain final concentration of PHE (10 ug/ml) and CTZ (10 ug/ml).The absorbance of the resulting solution was measured at 230.0 and 272.80 nm against solvent blank. Five replicate estimations were done in similar way and the concentration of each drug was obtained by using mentioned formulae.

Q -Absorbance Ratio Method:

The absorptivity values ( A^1%,1cm) of each drug at selected wavelengths were determined. The absorptivity values of PHE at 230.0 nm and 272.80 nm were 95.79 and 110.48 while respective values for CTZ were 110.10 and 22.10.The concentration of two drugs in mixture was calculated by using following equations:

Qm - Qy A₁

C_PHE = ------------------ X ----------- ---------------------- (1)

Qx – Qy ax₁

Qm - Qx A₁

C_CTZ = ------------------ X ----------- ------------------- (2)

Qy – Qx ay₁

Where,

A₂

Qm = -------

A₁

ax₂

Qx = --------

ax₁

ay₂

Qy = -------

ay₁

A₁ – Absorbance of lab. mixture at 230.0 nm.

A₂- Absorbance of lab. Mixture at 272.8 nm.

ax₁ – absorptivity of phenylephrine hydrochloride at 230.0 nm.

ax₂- absorptivity of phenylephrine hydrochloride at 272.8 nm.

ay₁– absorptivity of cetirizine hydrochloride at 230.0 nm.

ay₂- absorptivity of cetirizine hydrochloride at 272.8 nm.

Table1. Results for Validation Parameters:

Sr.No.	Validation parameters	Results
1	Working wavelengths	PHE CTZ 272.80 230.0
2	Linearity range (ug/mL)	5-30 5-30
3	Accuracy 80% 100% 120%	Percentage recovery (%) PHE CTZ 99.0 101.12 101.0 98.9 99.16 97.5
4	Precision A)Interday precision B)Intraday precision	PHE CTZ ±0.721, 0.717 ±0.416, 0.417 ±0.740, 0.739 ±0.433, 0.434
5	Ruggedness [% RSD] Analyst I [n=3]	PHE CTZ ±0.754, 0.753 ±0.725, 0.722
6	Repeatability [n=6]	PHE CTZ ±0.311, 0.307 ±0.804, 0.809

Validation:

Validation of proposed method was carried out for the following parameters as per ICH/USP16 guidelines. Accuracy of the proposed method was ascertained on the basis of recovery studies, performed by standard addition method. Accurately weighed quantities of preanalysed sample equivalent to 10.0 mg of PHE was taken in series of 100.0 ml volumetric flasks and to them known amount of PHE and CTZ were added at different concentration levels so as to produce solutions containing 80%,100% and 120% of label claim. Percentage recovery was calculated. The results are shown in Table1. Precision of the above method was ascertained by replicats are shown in Table1.

RESULTS AND DISCUSSION:

In 0.1 N HCl ,PHE and CTZ obeyed linearity in the concentration range of 5-30ug/ml for both drugs respectively at their respective λ max with correlation coefficient (r²=0.99) in both the case. Marketed brand of tablet were analyzed. The amount of PHE and CTZ determined by Q-absorbance ratio method was found to be 100.56 and 100.45 respectively. In these method precision was studied as repeatability (% RSD < 2) and inter and intra-day variations (%RSD < 2) for both drugs. Accuracy of the proposed method was ascertained on the basis of recovery studies, carried out by standard addition method at three different levels (80%, 100% 120%). The ruggedness of the method was studied by different analysts using the same operational and environmental conditions. The % recovery, repeatability data, ruggedness data were presented in Table 1.

CONCLUSION:

Developed method was found to be accurate, precise and rugged. Further, the developed method is simple and can usually be used for estimation of both these drugs in their combined dosage form. These uv method is applicable and overcome the drawbacks of other methods which are very costly. These method is used for routine analysis of drugs in bulk and pharmaceutical formulation.

ACKNOWLEDGEMENTS:

The authors are gratefully acknowledging Sun Pharma Pvt. Laboratories for providing the gift sample of PHE and CTZ HCl. Authors are also thankful to Vidyabharti College of Pharmacy, Amravati for providing necessary facilities for the research work.

REFERENCES:

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Received on 18.04.2013 Modified on 11.05.2013

Research J. Pharm. and Tech 6(7): July 2013; Page 761-764