Formulation Optimization & Evaluation of Oro-Dispersible Film of Levocetirizine & Montelukast Sodium

In recent years, orodispersible drug delivery systems have gained significant attention due to their ability to enhance patient compliance, especially among pediatric, geriatric, and dysphagic populations ^[1]. Orodispersible films (ODFs) are thin, flexible polymeric strips that disintegrate rapidly in the oral cavity without the need for water, offering a convenient and effective alternative to conventional dosage forms such as tablets and capsules ^[2]. Allergic conditions, including allergic rhinitis and asthma, are common chronic disorders that require prompt and effective pharmacological intervention ^[3]. Levocetirizine Dihydrochloride, a third-generation antihistamine, and Montelukast Sodium, a leukotriene receptor antagonist, are often prescribed together for synergistic management of these conditions. However, their conventional oral dosage forms may result in delayed onset of action and reduced patient adherence ^{[4, 5]}. To address these limitations, the development of an orodispersible film containing both Levocetirizine Dihydrochloride and Montelukast Sodium provides a promising drug delivery approach ^[6]. By employing the solvent casting method and optimizing the formulation through statistical design of experiments, specifically Central Composite Design (CCD), the goal is to achieve a formulation with rapid disintegration, acceptable mechanical properties, and enhanced drug release profile. This research focuses on the formulation, optimization, and evaluation of a dual-drug ODF using suitable film-forming polymers such as HPMC E5 and Doshion P542. The study aims to provide an innovative and patient-friendly dosage form with rapid onset of action and improved therapeutic outcomes for the management of allergic disorders.

MATERIALS AND METHODS:

Materials:

Levocetirizine Dihydrochloride & Sucralose (Medley Pharma Ltd, Andheri), Montelukast Sodium (Balaji Pharmaceuticals, Surat), HPMC E5 (Destiny Chemicals, Vadodara), Doshion P542 (Doshion Polyscience Pvt. Ltd., Ahmedabad), Glycerine & Polysorbate 80 (Research Lab Fine Chem Industries, Mumbai), Calcium Carbonate & Sodium Lauryl Sulphate (Vishal-Chem, Mumbai), Potassium Hydroxide (Merck Pvt. Ltd., Mumbai), Sodium Bicarbonate (Avantor Performance Materials India Pvt. Ltd., Thane), Orange Flavor (Flying Bird), Titanium Dioxide (Swastik Interchem Pvt. Ltd., New Delhi).

Methods:

Pre-formulation Studies:

Characterization of Pure APIs -

Organoleptic Properties

Levocetirizine Dihydrochloride & Montelukast Sodium was studied for organoleptic properties like colour, odour and taste ^[7].

Melting Point

Melting point of pure Levocetirizine Dihydrochloride & Montelukast Sodium was determined by using digital melting point apparatus by open capillary method ^[4].

Solubility

A small quantity of Levocetirizine Dihydrochloride & Montelukast Sodium was taken in two separate test tubes and the solubility was determined by dissolving the drug in 1 ml of different solvents ^[8].

Determination of λmax of Levocetirizine Dihydrochloride

Levocetirizine Dihydrochloride Solution (100µg/ml) was prepared in phosphate buffer pH 6.8 & UV spectrum was recorded using UV Visible spectrophotometer (Shimadzu 1800). The spectra of Levocetirizine dihydrochloride in phosphate buffer pH 6.8 scanned in the range of 200-400 nm & the wavelength of the maximum absorption was noted ^{[4, 9]}.

Standard Calibration Curve of Levocetirizine Dihydrochloride in Phosphate Buffer pH 6.8

From Standard stock solution of Levocetirizine Dihydrochloride (100µg/ml), appropriate aliquots were taken into different volumetric flasks and volume was made up to 10 mL with phosphate buffer pH 6.8, so as to get drug concentrations of 2, 4, 6, 8 & 10 µg/ml. The absorbance of these drug solutions was estimated at λmax 230.1 nm ^{[4, 9]}.

Determination of λmax of Montelukast Sodium

Montelukast Sodium Solution (100µg/ml) was prepared in phosphate buffer pH 6.8 + 0.1 % w/v of SLS & UV spectrum was recorded using UV Visible spectrophotometer (Shimadzu 1800). The spectra of Montelukast Sodium in phosphate buffer pH 6.8 scanned in the range of 200-400 nm & the wavelength of the maximum absorption was noted ^{[1, 10, 11]}.

Standard Calibration Curve of Montelukast Sodium in Phosphate Buffer pH 6.8 + 0.1 % w/v SLS

From Standard stock solution of Montelukast Sodium (100µg/ml), appropriate aliquots were taken into different volumetric flasks and volume was made up to 10 mL with phosphate buffer pH 6.8, so as to get drug concentrations of 5, 10, 15, 20 & 25 µg/ml. The absorbance of these drug solutions were estimated at λmax 345 nm ^{[1, 10, 11]}.

Fourier Transform Infrared Spectroscopy (FTIR)

The infrared spectra of drug, polymers, physical mixture of drug and polymers were recorded at a scanning range of 4000-400 cm-1 using FTIR spectrometer ^[12]. The infrared spectrum of pure Levocetirizine Dihydrochloride, pure Montelukast Sodium, HPMC E5, Doshion P542 & all blend was recorded and analyzed.

Differential Scanning Calorimetry (DSC)

Differential Scanning Calorimetry analysis was used to measure melting temperature and also to check the possibility of any interaction between drug and excipients used in the formulation. The DSC spectrum of pure Levocetirizine Dihydrochloride, pure Montelukast Sodium, HPMC E5, Doshion P542 & all blend was recorded and analyzed ^[13].

Dose Calculation

The drug to be loaded in the film was determined by the dose of the drug.

Method of Preparation of Levocetirizine Dihydrochloride & Montelukast Sodium Oro-Dispersible Film Using ODF Machine by Solvent Casting Method ^{[2, 6, 15]}:

(Day 1^st): Aqueous solution – I was prepared by dissolving film forming polymer (HPMC E5) in specific amount of distilled water. Then glycerine was added after homogeneous mixture formed and the solution was kept aside for 4 hrs or 24 hrs to remove entrapped air. Aqueous solution – II was prepared by dissolving Doshion P542 in distilled water slowly with continuous stirring for half an hour and this solution was allowed to swell for 24 hrs.

(Day 2^nd): Levocetirizine dihydrochloride was added to aqueous solution – II with continuous stirring for 20-25 min (pH 4-5). Aqueous solution - I & II were mixed and stirred properly. In another beaker potassium hydroxide solution was prepared having pH 10-12 & added dropwise in above solution to maintain pH 8-9. Calcium carbonate, sodium bicarbonate & sucralose were added to above solution and mixed properly.                Aqueous solution – III was prepared by dissolving montelukast sodium in distilled water, and then polysorbate 80 was added & sonicated for 5 min. Then orange flavor & titanium dioxide were added and mixed properly. Aqueous solution – III was added in the solution mixture of I & II. Then the solution was kept aside for 1hr to remove entrapped air. The solution was casted on TDP/ODF film former machine and dried at 70?C for 10-15 min. The film was carefully removed from surface of machine and cut according to required size and shape (2 cm length, 2 cm width) & stored in desiccator. The films were evaluated for various physicochemical tests.

Fig No.1: Orodispersible film of   Levocetirizine dihydrochloride & Montelukast sodium

Fig No. 2: TDP/ODF Machine

Optimization:

Modern optimization techniques using experimental design are a vital aid in formulation development as they help in developing the best possible formulation under a given set of conditions, thus saving time, money and development efforts. Current investigation aim at developing orodispersible film of levocetirizine dihydrochloride & montelukast sodium by using optimization technique ^[15].

Experimental Design:

Central Composite Design (CCD) ^[15]:

Central composite design (CCD) is a statistical optimization method commonly used in pharmacy and pharmaceutical research. It is a subset of response surface methodology (RSM) and is widely used to study the relationship between multiple variables and their effect on the response or outcome of interest. The Central Composite Design (CCD) was employed to systematically study the experimental design to investigate the effect of two independent variables (factors), i.e., Concentration of HPMC E5 (XA), Concentration of Doshion P542 (XB) on the dependant variables, i.e., % drug release of Levocetirizine dihydrochloride (Y1), % drug release of Montelukast sodium (Y2), disintegration time (Y3). In this study concentration of HPMC E5 (XA), Concentration of Doshion P542 (XB) was considered as formulation variables which varied, as required by experimental design & the numbers of other excipients were kept constant. The % drug release of Levocetirizine dihydrochloride (Y1), % drug release of Montelukast sodium (Y2), disintegration time (Y3) were selected as response variables. All analysis was performed by using the Design Expert Version 13.0.5.0 software.

Tablet No. 1: Composition of Batches (LM1-LM10) by Central Composite Design

*All ingredients are in mg.

Evaluation Parameter of Levocetirizine Dihydrochloride & Montelukast Sodium ODF ^{[2, 3, 14, 16, 17]}:

1. General Appearance

Evaluation was done by Visual perception and analysed various parameters like Colour, Surface texture, Transparency, Flexibility, etc.

2. Weight Variation

Weight variation was calculated by weighing any five films from the formulation individually on a digital balance and then computed the average weight.

3. Thickness

The thickness of film was measured by micrometer screw gauge at different strategic locations. Each film was measured at 5 positions (centre and four corners) by digital Vernier caliper and the mean thickness was calculated. This is essential to determine uniformity in the thickness of the film as this is directly related to the accuracy of dose in the film. The ideal thickness range of ODF is 0.05 – 0.1 mm.

4. Surface pH

The film to be tested placed in petri dish & was moistened with 0.5 ml to 1 ml of distilled water & kept for 30 sec. The pH was noted after bringing the electrode of the pH meter in contact with the surface of the formulation & allowing equilibrium for 1 min. The surface pH should be close to neutral, generally in the range of 6.2 – 7.6. It should not be too acidic or alkaline to avoid irritation when the film dissolves in the mouth.

5. Folding Endurance

Folding endurance is a critical method for determining a film’s mechanical qualities. It was determined by folding the film repeatedly at the same point until it breaks. The folding endurance value was calculated as the number of times of ODF can be folded without breaking.

6. Wetting Time

A circular single tissue paper was placed in the petridish. 6 ml of 1.1% w/v methylene blue solution was added to the petridish. The film was placed on the surface of tissue paper. The time required for the dye to appear on the surface of the film was noted as the wetting time.

7. Uniformity Drug Content

Take one film (2×2cm2) & dissolve it in pH 6.8 phosphate buffer in a volumetric flask & make up the volume upto q.s. to 100ml. Withdraw 0.5ml solution from prepared solution & diluted to 10ml with phosphate buffer pH 6.8. Measure the absorbance of the solution in UV Spectrophotometer at 230.1 nm & 345 nm for levocetirizine dihydrochloride & montelukast sodium respectively.

8. Disintegration Time

In – vitro disintegration time was determined visually by placing the film using tweezers in a glass beaker containing 20ml of distilled water. The disintegration time is the time when the film starts to break or disintegrate.

9. In-Vitro Dissolution Test

The release rate of Levocetirizine dihydrochloride & Montelukast sodium ODF was determined using United States Pharmacopoeia (USP) dissolution testing apparatus type 2 (Paddle method) .The dissolution test was performed using 900 ml of Phosphate buffer pH 6.8 + 0.1 % w/v SLS, at 37 ± 0.5?C and 50 rpm. In specified time intervals (0, 2, 4, 6, 8, 10 min) an aliquots of 5 ml samples of the solution were withdrawn from the dissolution apparatus and with replacement of fresh fluid to dissolution medium. The samples were filtered through whatmann filter paper of 42 µm. Absorbance of these solutions were measured at λmax 230.1 nm & 345 nm using a UV/Visible Spectrophotometer (Shimadzu-1800). The drug release was plotted against time to determine the release profile of various batches.

10. Stability Studies

Stability studies were carried out as per ICH guidelines Q1A (R2). The optimized formulation (LM 5) was wrapped in aluminium pouch & sealed. It was stored at accelerated (40?c ±2?c, 75% RH ± 5% RH) conditions for a period of one month. Films were evaluated for weight, folding endurance, disintegration time, drug content and % DR.

RESULT & DISCUSSION:

Organoleptic Properties

Levocetirizine dihydrochloride was found to be white coloured powder, while Montelukast sodium was pale yellow coloured powder. Both the APIs were odourless & bitter in taste.

Melting Point

Melting point of levocetirizine dihydrochloride & montelukast sodium was found in the range between 217–220°C and 146–148 °C respectively.

Solubility

Levocetirizine dihydrochloride was found to be freely soluble in water and slightly soluble in ethanol. Montelukast sodium was found to be freely soluble in methanol, water, DMF & DMSO. But when added to phosphate buffer pH 6.8, it gives whitish solution. So the solubility was done by using SLS.

Absorption Maxima of Levocetirizine Dihydrochloride & Montelukast Sodium

λmax of Levocetirizine dihydrochloride & Montelukast sodium was found to be 230.1 nm and 345 nm respectively.

Fig No.3: UV Spectrum of Levocetirizine Dihydrochloride in Phosphate Buffer pH 6.8

Fig No.4: UV Spectrum of Montelukast Sodium in Phosphate Buffer pH 6.8 + 0.1 % w/v SLS

Standard Calibration Curve of Levocetirizine Dihydrochloride in Phosphate Buffer pH 6.8

Table No.2: Observation Table for Calibration Curve of Levocetirizine Dihydrochloride

Fig. No.5: Calibration Curve of Levocetirizine Dihydrochloride in Phosphate Buffer pH 6.8

Standard Calibration Curve of Montelukast Sodium in Phosphate Buffer pH 6.8 + 0.1 % w/v SLS

Table No.3: Observation Table for Calibration Curve of Montelukast Sodium

Fig No.6: Calibration Curve of Montelukast Sodium in Phosphate Buffer pH 6.8 + 0.1 % w/v SLS

Fourier Transform Infrared Spectroscopy (FTIR)

Fig. No.7: FTIR Spectrum of Levocetirizine Dihydrochloride

Fig. No.8: FTIR Spectrum of Montelukast Sodium

Fig. No.9: FTIR Spectrum of Levocetirizine Dihydrochloride & Montelukast Sodium with Polymers

Fig. No.10: DSC Thermogram of Levocetirizine Dihydrochloride

Fig. No.11: DSC Thermogram of Montelukast Sodium

Fig. No.12: DSC Thermogram of Levocetirizine Dihydrochloride & Montelukast Sodium with Polymers

General Appearance

All the ODFs of batch LM1-LM10 were found to be orange in colour, translucent, smooth surface texture and flexible.

Weight Variation

Weight variation of the films of LM1-LM10 was found in the range 88.7±0.02 mg to 95.6±0.02 mg. Result was shown in table 4.

Thickness

Film thickness of formulation LM1-LM10 was found in the range 0.052±0.01 mm to 0.061±0.02 mm. Results of thickness are shown in table 4.

Surface pH

Surface pH of orodispersible film was found to be in between pH 6.27±0.3 to 6.81±0.4 (n=3). Results of thickness are shown in table 4.

Folding Endurance

Folding endurance of formulation LM1-LM10 was found in the range 98±1.56 to 106±1.33. Among all batches, LM 5 batch shows higher folding endurance, while batch LM 9 showed lower folding endurance. Results of thickness are shown in table 4.

Wetting Time

Wetting time of formulation LM1-LM10 was found in the range 18.33±3.01 sec to 23.18±2.55 sec. The optimized formulation LM 5 showed wetting time of 18.44±2.14 sec. Results of thickness are shown in table 5.

Uniformity Drug Content

Uniformity Drug Content of levocetirizine dihydrochloride of formulation LM1-LM10 was found in range 92.80% to 97.26%. Uniformity Drug Content of montelukast sodium of formulation LM1-LM10 was found in range 91.99% to 96.01%. Results of thickness are shown in table 5.

Disintegration Time

Disintegration time of formulation LM1-LM10 was found in the range 15.16 sec to 20.10 sec. This shows that the ODFs disintegrate within standard limits. Results of thickness are shown in table 5.

*All the values were in mean ±SD, n=3

Table No.5: Evaluation of Batches of Levocetirizine Dihydrochloride & Montelukast Sodium ODF generated by CCD

*All the values were in mean ±SD, n=3

In-Vitro Dissolution Test

In-vitro % drug release of levocetirizine dihydrochloride and montelukast sodium of optimized formulation LM 5 was found to be 93.46% & 92.53% respectively within 10 minutes. The results were showed in table 6, 7. The Graphs of % drug release were showed in fig no.13, 14.

Table No.6: In-Vitro % DR of Levocetirizine Dihydrochloride in Batches of ODF generated by CCD

Fig. No.13: % DR of Levocetirizine Dihydrochloride in Optimized Batches of ODF

Table No. 7: In-Vitro % DR of Montelukast Sodium in Batches of ODF generated by CCD

Fig. No.14: % DR of Montelukast Sodium in Optimized Batches of ODF

Data Analysis:

1. % Drug Release of Levocetirizine Dihydrochloride:

Final equation in terms of coded form,

% DR of levocetirizine dihydrochloride (Y1) = +95.03 + 2.79 X1 + 0.8112 X2

Concerning dissolution, the results of multiple linear regression analysis showed that the coefficients X1 bear positive sign and X2 bear a positive sign. It revealed that % drug release of levocetirizine dihydrochloride increases with increases in HPMC E5 and Doshion P542. ANOVA was used to identify the significant effect. The result was found to be significant at that level of probability 0.0226.

2. % Drug Release of Montelukast Sodium:

Final equation in terms of coded form,

% DR of Montelukast sodium (Y2) = +94.32 + 3.10 X1 + 0.6974 X2

Concerning dissolution, the results of multiple linear regression analysis showed that % drug release of Montelukast sodium increases with increases in HPMC E5 and % drug release increases with increase in Doshion P542. ANOVA was used to identify the significant effect. The result was found to be significant at that level of probability 0.0188.

3. Disintegration Time:

Final equation in terms of coded form,

Disintegration time (Y3) = +15.34 – 0.6358 X1 ? 0.0082 X2 + 0.6200 X1X2 + 0.7425 X1² + 2.23 X2²

Concerning dissolution, the results of multiple quadratic regression analysis showed that the coefficients X1 and X2 bear negative sign. It revealed that disintegration time of film decreases with increases in HPMC E5 & Doshion P542. ANOVA was used to identify the significant effect. The result was found to be significant at that level of probability 0.0099.

Table No.8: Result of Analysis of Variance of Batches Generated by CCD for Levocetirizine Dihydrochloride & Montelukast Sodium ODF

* DF indicates degree of freedom; SS sum of square; MS mean sum of square and F is Fischer’s   ration

Graphical Representation

Stability Studies

Table No.9: Stability Study of Optimized Batch of ODF Levocetirizine Dihydrochloride & Montelukast Sodium

CONCLUSION: