INTRODUCTION:

Oral route is the most preferred route of administration by patients. Drug delivery to paediatric patients is always a challenge. Recently, more emphasis is laid down on the development of pharmaceutically elegant & patient friendly drug delivery systems for both paediatric patients^1,2. Many paediatric patients find it difficult to swallow tablets and capsules, which lead to high incidence of non-compliance and ineffective therapy. The jelly dosage form can be administered without water and are soft and smooth³.

The problem of dose measurement by patients is overcome as oral medicated jellies are packed in unit dose. Jellies can be versatile in nature that they can be used as such or taken with food items⁴. Jellies are formed by aggregation of polymers with at least two components; the gelling agent and the fluid component. Gellan gum, carrageenan, pectin, sodium alginate and gelatin are widely used gelling agents in pharmaceutical industries. Salbutamol sulphate is a short-acting β₂-adrenergic receptor agonist used for the relief of bronchospasm in conditions such as asthma and chronic obstructive pulmonary disease (COPD)^5,6.

Salbutamol sulphate is a short acting beta-adrenergic agonist which is used for its bronchodilating properties in the management of disorders with reversible airways obstruction such as in asthma and in COPD. Salbutamol sulphate has a short half life with an oral bioavailability of 30 - 50% due to extensive first pass metabolism in liver, degradation in colon and has a site-specific absorption in stomach and upper part of small intestine. The half life of salbutamol sulphate is about 4.5 h. Preparation of oral soft jellies of salbutamol sulphate would be advantageous as it provides faster onset of action to relieve the symptoms of asthma.

Hence, the present research was mainly focused on the development and evaluation of paediatric oral soft jellies of salbutamol sulphate that would be patient friendly and provide faster onset of action to relieve the symptoms of asthma immediately.

MATERIALS AND METHODS:

Salbutamol sulphate was a gift sample received from Jayco Chemicals. Sorbitaol, Polyethylene glycol 400 were procured from Loba Chemie Pvt., Ltd. Glycerin, Sodium citrate were obtained from Finar Chemicals Ltd. Gelatin, Sucrose, Propyl paraben were purchased from Sd Fine-Chem Ltd. Methyl cellulose, Sodium carboxy methyl cellulose, Methyl paraben were procured from Merck Specaialities Pvt., Ltd, Amit Cellulose Products and Oxford Laboratory respectively. Aspartame was purchased from HiMedia laboratories Pvt., Ltd. All the chemicals and reagents used were of analytical grade.

PREFORMULATION STUDIES:

Solubility analysis: Pre-formulation solubility analysis was done, which include the selection of suitable solvent systems to dissolve the drug as well as various excipients.

Determination of melting point:

Melting point determination of the obtained drug sample was done; as it is a first indication of purity of the sample. The presence of relatively small amount of impurity can be detected by lowering and widening in the melting point range.

Drug - excipients compatibility studies⁷:

The objective of the compatibility study was to determine the compatibility of the drug and the polymer or excipients using Fourier transform infra-red (FTIR) analysis.

FTIR analysis :

An FT-IR spectrophotometer was used for infrared analysis of samples. About 4 to 5 mg of sample was mixed with dry potassium bromide (KBr) and the sample was examined at transmission mode over the wave number range of 4000 - 400 cm^-1.

FORMULATION DEVELOPMENT:

Calibration of standard curve of salbutamol sulphate

Preparation of phosphate buffer solution, pH 6.8:

0.2 M NaOH (23.65 ml) was added to 50 ml of 0.2 M KH₂PO₄ and diluted to 200 ml with distilled water.

Preparation of standard solution of salbutamol sulphate:

100 mg of salbutamol sulphate drug was weighed accurately and transferred to 100 ml of volumetric flask. Then phosphate buffer solution, pH 6.8 was added to dissolve the drug completely. The volume was made up to 100 ml with solvent. The prepared sample was 1000 µg/ml.

Preparation of working solution of salbutamol sulphate:

From the standard solution of salbutamol sulphate, different concentrations (20, 40, 60, 80 and 100 µg/ml) were prepared by transferring suitable aliquots into 100 ml volumetric flask and the final volume was made up with phosphate buffer solution, pH 6.8. For the prepared solutions, absorbance was measured at 276 nm by using UV-Visible spectrophotometer and reagent blank as phosphate buffer solution, pH6.8. Then the calibration curve was constructed by taking concentration on X-axis and absorbance on Y-axis. The regression equation and correlation coefficient were determined.

PREPARATION OF ORAL SOFT JELLIES OF SALBUTAMOL SULPHATE:

Preliminary studies for gelling agents:

Preliminary studies were carried out for the selection of gelling agents and optimizing their concentrations. Jellies were prepared using gelling agents alone without drug. Preliminary trials were conducted with natural polymers (gelatin - 1.0%, 1.5%, 2% & pectin – 1.0%, 1.5%, 2.0%, 2.5%) and semi-synthetic polymers (methyl cellulose – 1.0%, 1.5%, 2.0%, 2.5% & sodium CMC – 0.5%, 1.0%) alone in various concentrations. Formulation of oral soft jellies of salbutamol sulphate was further carried out based on the best formulations obtained at the end of preliminary trials.

Formulation of oral soft jellies of salbutamol sulphate:

Formulations, F1 to F3 were prepared using gelatin (1.0, 1.5 and 2%) alone. Gelatin-methyl cellulose combinations were used to prepare F4 – F6. Gelatin-sodium CMC combinations were employed to prepare the formulations, F7 - F9. Salbutamol sulphate (0.2%) and other excipients were present in all formulations. PEG 400 (3%) and glycerin (3%) were used as solubility enhancers of salbutamol sulphate; sodium citrate 0.3% as taste enhancer; sorbitaol (70%) in solution, sucrose (30%) and aspartame (0.3%) as sweetening agents; methyl paraben (0.18%) and propyl paraben (0.02%) as preservatives; orange flavour (2%) and purified water (up to 100%) as vehicle were used. All ingredients were calculated on the basis of % w/w.

Accurately weighed polymer powder (gelling agent) was dispersed in 10 ml of purified water maintained at 90 °C throughout the preparation. The dispersion was stirred using a magnetic stirrer (Remi Equipment Pvt. Ltd., Mumbai, India) for 20 min in order to facilitate hydration of gelling agent. Salbutamol sulphate was taken in another beaker and solubilized using polyethylene glycol 400 and glycerin. The obtained drug solution was added to the hydrated gelling agent followed by addition of sorbitol 70% w/v and sucrose under continuous stirring. Then aspartame, sodium citrate, preservatives and orange flavour were added under continued stirring at 60 °C. The final weight was adjusted with purified water, mixed, transferred to polyethylene molds, sealed and allowed to cool at room temperature (25 °C ± 5 °C) to form a jelly like texture.

EVALUATION OF ORAL JELLIES:

Physical observation:

The medicated jelly was examined for physical appearance in terms of clarity, texture and consistency. Texture of the medicated jelly in terms of stickiness and grittiness was evaluated by visual inspection of the product after mildly rubbing the jelly sample between two fingers.

Viscosity:

Viscosity of F1 to F9 formulations were measured using Brookfield DV – II + Pro viscometer. The medicated jelly was squeezed out from the polyethylene plastic bag by making a cut of uniform size on the bag and viscosity had been measured using spindle number LV4 at the rotation of 50 RPM at 25 °C ± 1 °C. The viscosity measurements were made in triplicate using fresh samples each time.

pH:

The pH of prepared jellies was measured using a digital pH meter at room temperature (25 ^oC ). For this purpose 0.5 g of jelly was dispersed in 50 ml of distilled water to make a 1% solution and the reading was noted.

Weight variation and drug content:

The average weight of ten jellies was taken to determine weight variation. The jellies were taken out of the molds in a beaker and weighed individually, pooled and mixed. Then jelly equivalent to 100 mg of salbutamol sulphate was taken in 100 ml volumetric flask, dissolved and made up to the volume using phosphate buffer solution, pH 6.8. The drug content was estimated by UV - visible spectrophotometer at 276 nm after filtering the sample through Whatman filter paper.

Syneresis:

Syneresis is the contraction of the gel upon storage and separation of water from the gel. It is more pronounced in the gels, where lower concentration of gelling agent is employed. All the jellies were observed for signs of syneresis at room temp 25°C ± 5 °C and 8 °C ± 1 °C. The formulations showing signs of syneresis were rejected and not considered for further studies.

In vitro dissolution studies:

In vitro dissolution was studied using type II USP dissolution test apparatus (Lab India Analytical Instruments Pvt. Ltd., Thane, India) in phosphate buffer solution, pH 6.8 (900 ml, 37 °C ± 0.5 °C) dissolution medium at 50 rpm. 5 ml samples were withdrawn at 5, 10, 15, 20, 25, 30, 40, 50 and 60 min using a pre-filter. The sample was replaced by an equal volume of buffer solution in order to maintain constant volume throughout. The amount of salbutamol sulphate dissolved was determined using a calibration curve at 276 nm after suitable dilution. The percentage of drug released was calculated from the dissolution data.

RESULTS AND DISCUSSION:

Pre-formulation studies of salbutamol sulphate:

The following pre-formulation studies were performed on salbutamol sulphate, polymers and excipients.

Analytical report for API:

Table 1: Analytical report for salbutamol sulphate

Preformulation test	Results
Description	White
Odour	Odourless
Nature	Salt form
Solubility	Sparingly soluble in water; soluble in ethanol (96%); slightly soluble in ether; easily soluble in 0.1N HCl and buffers.
Category	β₂-adrenergic receptor
Melting Point	157-158 ^oC

Table 2: Salbutamol sulphate characterization

Test	Result
Particle size (μm)	09.22 ± 0.5
Bulk density (g/cc)	0.421 ± 0.02
Tapped density (g/cc)	0.506 ± 0.04
Carr’s index	16.79 ± 0.03
Hausner’s ratio	1.20 ± 0.02
Angle of repose (^o)	24.33 ± 0.02

Drug – polymer-excipients compatibility studies: The interaction studies were carried out to ascertain any kind of interaction of drug with the excipients used in the preparation of oral soft jellies.

Interpretation of Salbutamol sulphate:

Fig. 1: FT-IR spectra of salbutamol sulphate

Fig. 2: FT-IR spectra of optimized formulation F5

Fig. 3: FT-IR spectra of optimized formulation F7

Inference:

The FT – IR spectrum of salbutamol sulphate pure drug (Fig. 5) showed sharp peaks at 1026 cm^-1 (C-O stretching) and at 1642 cm^-1 (O-H bending). The identical peaks were also present in oral jelly formulations (F5 & F7) containing salbutamol sulphate. All the similar peaks were also observed in the oral jellies, indicating that there was no incompatibility between the drug and the excipients used (Fig. 6 & Fig. 7).

Table 3: FT-IR spectral interpretation of salbutamol sulphate pure drug and optimzied formulations

Interpretation	IR absorption bands (cm^-1)
Interpretation	Salbutamol sulphate pure drug	Formulation F5	Formulation F7
C=O stretching	1026	1041	1041
O-H bending	1642	1642	1642

FORMULATION DEVELOPMENT:

Standard curve of salbutamol sulphate:

The standard graph of salbutamol sulphate in phosphate buffer solution, pH6.8 was constructed by making the solutions of 20 µg/ml, 40 µg/ml, 60 µg/ml, 80 µg/ml and 100 µg/ml concentrations. The absorbance of solutions was measured using UV-visible spectrophotometer at an absorption maximum of 276 nm. The standard graph was constructed by taking the absorbance on Y-axis and concentrations on X-axis. Drug concentration and absorbance followed linear relationship and the correlation coefficient value (R²) in phosphate buffer solution pH6.8 was found to be 0.999 as shown in Table No. 7 & Fig. 8.

Table 4: Standard calibration curve of salbutamol sulphate

Concentration (µg/ml)	Absorbance at 276.0 nm (in phosphate buffer solution, pH6.8)
0	0.000
20	0.161
40	0.339
60	0.531
80	0.728
100	0.927

Fig. 4: Standard calibration curve of salbutamol sulphate in phosphate buffer solution, pH 6.8

PREPARATION OF ORAL SOFT JELLIES:

Preliminary studies for gelling agents:

Jellies were prepared using gelling agents alone without drug. Preliminary trials were conducted with natural polymers gelatin, methyl cellulose and sodium CMC alone in various concentrations. Placebo jellies made with gelatin (1.0%, 1.5%, 2%) were observed to be transparent, acceptable in consistency and non-sticky. Jellies prepared using 1% pectin showed sticky, semi-liquid consistency. The consistency of pectin jellies found to be unimproved even when used in higher concentrations (1.5%, 2.0%, 2.5%). Methyl cellulose jellies (1.0%, 1.5%, 2.0%, 2.5%) were non-transparent and sticky in nature with semi-liquid consistency. Jellies made with sodium CMC (0.5%, 1.0%) were too sticky in nature and semi-liquid consistency.

Preparation of oral medicated soft jellies:

Paediatric oral soft jellies of salbutamol sulphate were successfully prepared using gelling agents: gelatin, gelatin-methyl cellulose combination, gelatin-sodium carboxy methyl cellulose combination in various concentrations.

Fig. 5: Soft jelly formulations of salbutamol sulphate

EVALUATION OF ORAL SOFT JELLY FORMULATIONS:

Physical observation:

Physical observation of jellies is important to justify the patient acceptance and compliance of the formulations. The observed parameters were summarized in Table 8. All the jellies were found to be transparent. The jellies were acceptable in nature with varying degrees of consistency. A non-sticky texture was observed in all formulations, except those of formulation F9. Formulation F9 was thick and sticky due to the presence of high concentration of sodium CMC. The color and odor of all the jelly formulations were in an acceptable range. All the prepared formulations were observed to be soft with no grittiness feel evaluated when the jelly samples were rubbed between two fingers.

Table 5: Physical observation of prepared jellies

Formulation*	Appearance	Consistency	Texture
F1	Transparent	Acceptable	Non-sticky
F2	Transparent	Acceptable	Non-sticky
F3	Transparent	Acceptable	Non-sticky
F4	Transparent	Acceptable	Non-sticky
F5	Transparent	Acceptable	Non-sticky
F6	Transparent	Acceptable	Non-sticky
F7	Transparent	Acceptable	Non-sticky
F8	Transparent	Slightly thick	Slightly sticky
F9	Transparent	Thick	Sticky

*Formulations of gelatin (F1-F3), gelatin-MC combination (F4-F6) and gelatin-sodium CMC (F7-F9) combination

Rheological measurement:

The viscosities of salbutamol sulphate jellies were found between 5438 cp ± 0.76 and 10837 cp ± 0.92 as shown in Table No. 9 and varied depending on the type and concentration of gelling agent. The viscosities of all the formulations (F1 to F7) were found to be within the acceptable range. Formulation F5 prepared from gelatin-methyl cellulose combination (0.5% gelatin & 1.0% methyl cellulose) and Formulation F7 (0.5% gelatin & 1.0% sodium CMC) showed optimum viscosity. Formulation F8 and F9 showed higher viscosities of 9692 cp ± 1.24 and 10837 cp ± 0.92 respectively which resulted in too sticky and thick jellies. The concentration of the gelling agent directly influenced the viscosity. From the results, it was evident that the higher the concentration of gelling agent, the greater would be the rheological properties of jellies.

pH of jelly formulations:

The results of pH measurements for the prepared jelly formulations were summarized in Table No. 10. The pH of the formulation influences the taste and stability of oral jellies. The pH of the developed jellies was found in the range of 6.54 ± 0.06 ‑ 6.74 ± 0.02 which was slightly acidic.

Weight variation and drug content:

The weight variation was found between 0.99% ± 1.24 and 1.01% ± 0.74 in all prepared jelly formulations. The drug content was found in the range of 98.23% ± 0.58 to 99.25% ± 0.35, which was in conformity with the pharmacopoeial specification of 98% -101%.

Table 6: Results of rheological properties, pH of developed oral jelly formulations

Formulation*	Viscosity (cp)	pH of the jelly	Drug content (%)
F1	5438 ± 0.76	6.55 ± 0.02	98.78 ± 0.33
F2	6370 ± 0.33	6.54 ± 0.06	98.23 ± 0.58
F3	7144 ± 0.62	6.57 ± 0.02	98.64 ± 0.41
F4	5627 ± 1.24	6.65 ± 0.04	98.71 ± 0.62
F5	6882 ± 0.88	6.72 ± 0.03	99.25 ± 0.35
F6	7023 ± 0.55	6.63 ± 0.06	98.67 ± 0.48
F7	7134 ± 0.57	6.74 ± 0.02	99.19 ± 0.67
F8	9692 ± 1.24	6.58 ± 0.04	98.36 ± 0.29
F9	10837 ± 0.92	6.67 ± 0.02	98.58 ± 0.54

Syneresis:

Gels experience syneresis or de‑swelling due to the release of liquid, resulting in shrinkage of gels and reduced quality (Lucey JA, 2002). Syneresis was more pronounced in the gels, where lower concentration of gelling agent was employed. It was observed after 24 h of jelly preparation. None of the developed jelly formulations showed syneresis at room temperature (25 °C ± 5°C) and 8 °C ± 1 °C. Syneresis was not noticed at room temperature may be due to the binding of free water by co‑solute^8,9.

In vitro dissolution testing:

The in vitro dissolution study was performed to compare salbutamol sulphate release kinetics from the developed jelly formulations. The results were summarized in Table 7. Rate of dissolution of salbutamol sulphate from F5 (gelatin - methyl cellulose combination) and F7 (gelatin - sodium CMC combination) was found to be higher and in conformance with the bio-pharmaceutical classification system (BCS) concept for the immediate release formulations (>85% in 30 min). The complete drug release was observed to be achieved within 60 min in case of Formulations F5 & F7. More than 85% of drug release was observed within 60 min in case of all formulations except in F8 and F9. Slower drug release in formulations F8 and F9 could be due to the higher concentration of gelatin -sodium CMC combination which resulted in formation of thick jellies and slower drug diffusion.

Fig. 10: In vitro drug release profiles of salbutamol jelly formulations (F1 - F9)

*Formulations of gelatin (F1-F3), gelatin-MC combination (F4-F6) and gelatin-sodium CMC (F7-F9) combination

SUMMARY:

Preliminary trials were conducted with natural polymers gelatin, methyl cellulose and sodium CMC alone in various concentrations. Placebo jellies made with gelatin (1.0%, 1.5%, 2%) were observed to be transparent, acceptable in consistency and non-sticky. Jellies prepared using 1% pectin showed sticky, semi-liquid consistency. The consistency of pectin jellies found to be unimproved even when used in higher concentrations (1.5%, 2.0%, 2.5%). Methyl cellulose jellies (1.0%, 1.5%, 2.0%, 2.5%) were non-transparent and sticky in nature with semi-liquid consistency. Jellies made with sodium CMC (0.5%, 1.0%) were too sticky in nature and semi-liquid consistency.

Physical observation of jellies is important to justify the patient acceptance and compliance of the formulations. All the jellies were found to be transparent. The jellies were acceptable in nature with varying degrees of consistency. A non-sticky texture was observed in all formulations, except those of formulation F9. Formulation F9 was thick and sticky due to the presence of high concentration of sodium CMC. The colour and odour of all the jelly formulations were in an acceptable range. All the prepared formulations were observed to be soft with no grittiness feel evaluated when the jelly samples were rubbed between two fingers.

The viscosities of salbutamol sulphate jellies were found between 5438 cp ± 0.76 and 10837 cp ± 0.92 and varied depending on the type and concentration of gelling agent. The viscosities of all the formulations (F1 to F7) were found to be within the acceptable range. Formulation F5 prepared from gelatin-methyl cellulose combination (0.5% gelatin & 1.0% methyl cellulose) and Formulation F7 (0.5% gelatin and 1.0% sodium CMC) showed optimum viscosity. Formulation F8 and F9 showed higher viscosities of 9692 cp ± 1.24 and 10837 cp ± 0.92 respectively which resulted in too sticky and thick jellies. The concentration of the gelling agent directly influenced the viscosity. From the results, it was evident that the higher the concentration of gelling agent, the greater would be the rheological properties of jellies.

The pH of the formulation influences the taste and stability of oral jellies. The pH of the developed jellies was found in the range of 6.54 ± 0.06 ‑ 6.74 ± 0.02 which was slightly acidic.

None of the developed jelly formulations showed syneresis at room temperature (25 °C ± 5°C) and 8°C ± 1 °C. Syneresis was not noticed at room temperature may be due to the binding of free water by co‑solute.

From the results of in vitro dissolution study, it was found that the rate of dissolution of salbutamol sulphate from F5 (gelatin - methyl cellulose combination) and F7 (gelatin - sodium CMC combination) was found to be higher and in conformance with the bio-pharmaceutical classification system (BCS) concept for the immediate release formulations (>85% in 30 min). The complete drug release was observed to be achieved within 60 min in case of Formulations F5 & F7. More than 85% of drug release was observed within 60 min in case of all formulations except in F8 and F9. Slower drug release in formulations F8 and F9 could be due to the higher concentration of gelatin-sodium CMC combination which resulted in formation of thick jellies and slower drug diffusion.

CONCLUSION:

In the present study, paediatric oral soft jellies loaded with salbutamol sulphate were successfully formulated using gelatin alone, gelatin-methyl cellulose and gelatin-sodium CMC combination as gelling agents. The optimized formulations F5 and F7 showed acceptable physicochemical properties and drug release.

ACKNOWLEDGEMENTS:

The authors are grateful to the principal and management of Vijaya Institute of Pharmaceutical Sciences for Women, Enikepadu, Vijayawada for providing the necessary research facilities.

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Received on 01.06.2018 Modified on 24.06.2018

Research J. Pharm. and Tech 2018; 11(11): 4939-4945.

DOI: 10.5958/0974-360X.2018.00899.5

Time (min)	F1	F2	F3	F4	F5	F6	F7	F8	F9
0	0	0	0	0	0	0	0	0	0
5	23.25	25.01	24.34	28.21	35.87	30.43	34.91	33.12	28.98
10	33.12	33.93	34.25	37.12	42.93	34.92	41.23	36.01	32.92
15	45.19	44.56	44.92	48.91	55.56	45.17	54.39	39.23	37.17
20	54.43	55.31	56.06	53.39	67.99	50.78	66.55	42.52	41.35
25	68.32	64.76	65.18	68.26	79.76	65.37	78.48	45.68	44.73
30	73.23	76.87	74.25	76.82	88.37	74.14	87.63	49.27	47.09
40	76.56	80.89	77.64	80.91	91.52	81.06	91.33	55.92	53.64
50	78.62	84.76	80.25	82.64	95.69	83.65	96.41	60.89	59.37
60	85.76	88.12	86.92	86.15	98.34	87.37	98.17	68.44	67.23