DEVELOPMENT, OPTIMIZATION AND EVALUATION OF HERBAL GEL FORMULATION

DEVELOPMENT, OPTIMIZATION AND EVALUATION OF HERBAL GEL FORMULATION

Kinjal Patel * and Maitreyi Zaveri

Department of Pharmacognosy, K. B. Institute of Pharmaceutical Education and Research, Kadi Sarva Vishwa Vidyalaya, Gandhinagar, Gujarat, India.

ABSTRACT: Acne vulgaris is one of the most common chronic inflammatory skin diseases affecting more than 85% of adolescents worldwide. Quercetin, curcuminoids, and berberine HCl have anti-acne, anti-inflammatory, antibacterial, and antioxidant characteristics. This study aimed to develop, optimize and evaluate herbal gel containing quercetin, curcuminoids, and berberine HCl. A preliminary trial was conducted for the screening of polymers. A 3² full factorial design was applied to investigate the combined effect of the two independent variables, i.e., the concentration of carbopol 934 and the concentration of propylene glycol, on the dependent variables viscosity and cumulative percent drug release at 8 hrs. The optimized formulation (D0) shows a viscosity of 78123.67±0.69 cps, cumulative percent drug release of quercetin 85.99±1.03%, berberine HCl 35.38± 0.45% and curcuminoids 70.28± 1.18%. An FTIR investigation of drug excipient compatibility revealed no interactions between drugs and excipients. Based on all parameters and experimental design evaluations, it was determined that viscosity increased with increasing carbopol 934 and propylene glycol concentrations; cumulative percent drug release decreased with increasing carbopol 934 concentrations and increased with increasing propylene glycol concentrations.

Keywords: Acne, Carbopol 934, Propylene glycol, Quercetin, Curcuminoids, Berberine HCl

INTRODUCTION: Acne vulgaris is a common skin disorder, due to chronic inflammation of sebaceous follicles, is characterized by tender inflammatory papules and nodules. Acne usually arises on the face, forehead, chest, upper back, and shoulders since these are the areas of skin with the most oil glands. According to the Global Burden of Disease research, acne vulgaris affects more than 85 percent of young people worldwide and can strike at any age. It typically appears throughout puberty and worsens during adolescence and is classified as an adolescent disease that affects almost 80% of the population between the ages of 11 to 30 ^{1, 2, 3}.

Acne is treated with retinoids, topical or systemic antibiotics, and other medications. The most serious issue with antibiotic use is resistance and its consequences; oral isotretinoin is teratogenic ⁴. Plants are a natural source of medicine that can be utilized to treat a wide range of dermatological problems due to their efficacy and devoid of side effects ⁵.

Based on literature evaluations, we selected quercetin, curcuminoids, and berberine HCl for herbal gel formulation since they have anti-inflammatory, anti-acne, antibacterial, and antioxidant characteristics ^6-12. As a result, this study aimed to develop, optimize and evaluate herbal gel formulation for acne treatment.

MATERIAL AND METHODS:

Reagents and Chemicals: Quercetin, berberine HCl and curcuminoids were procured from Yucca enterprises, Mumbai; Sodium alginate, Na CMC and HPMC K100M were procured from Astron chemicals (India); HEC were procured from Yarrow chem product, Mumbai; Carbopol 934 were procured from Research-lab fine chem Industries; Propylene glycol and Triethanolamine were procured from S.D. fine chemicals, Mumbai.

Drug Excipients Compatibility Study using FTIR: The IR spectra were acquired using an FTIR using the KBr pellet technique, and the wavelength range was between 4000 and 400 cm^-1. The spectra obtained for drugs and physical mixtures of drugs with polymers were observed ¹³.

Screening of Polymers: Preliminary screening was performed to confirm the effect of various polymers on herbal gel formulation Composition of preliminary trial batches of herbal gel is shown in Table 1. The resulting gel was evaluated for viscosity, homogeneity, and clarity ^14-18.

TABLE 1: PRELIMINARY TRIAL BATCHES OF HERBAL GEL FOR SCREENING OF POLYMERS

HPMC K100M- Hydroxy propyl methyl cellulose K100M, HEC- Hydroxy ethyl cellulose, Na CMC- Sodium carboxy methyl cellulose.

Optimization of Formulation as Per 3² Full Factorial Design: A 3² full factorial design was applied for optimization of the formulation. The concentration of carbopol 934 and the concentration of propylene glycol was taken as independent variables; viscosity and cumulative percent drug release at 8 hrs (Q8) were taken as dependent variables. We evaluated the response using a statistical model that included interactive and polynomial terms Table 2.

TABLE 2: VARIABLES IN 3² FULL FACTORIAL DESIGN

Method of Preparation of Gel Formulation: Weighed quantity of carbopol 934 was soaked overnight in purified water containing sodium benzoate to ensure complete swelling of the polymer. Then propylene glycol was added. Drugs were accurately weighed and dissolved in ethanol in a stoppered glass vial, slowly added to the polymeric mixture, and homogenized in Triethanolamine was added in an amount (q.s.) sufficient to neutralize the pH. Then, distilled water was added to make q.s. to 100 gm with continuous stirring using mechanical stirrers Composition of factorial batches is shown in Table 3 ^{14, 15, 16, 18}.

TABLE 3: COMPOSITION OF FACTORIAL BATCHES

Evaluation of Gel:

Viscosity: The viscosity of the gel formulation was determined at a temperature of 25.0 ± 0.5 °C using a viscometer (Brookfield DV-III+ Rheometer TC-502 Temperature Controller, USA). Spindle speeds have been adjusted to give the highest torque values in the 10-100% range, as the Brookfield instruction manual recommended. Viscosity was measured using spindles # 64 and 5 rpm ^{15, 18}.

Homogeneity: Visual inspection in the presence of light techniques was adopted to check the homogeneity of gel ¹⁸.

pH Measurement: After calibration of pH meter using standard buffer solution at pH 4, 7, 9; the determinations were carried out in triplicate by dipping the glass electrode entirely into the formulation, and the average was calculated ¹⁸.

Spreadability: The gel was transferred to a glass slide and covered with an equivalent slide. The slides are arranged to have the gel interposed up to 7.5 cm. A weight of 100 g was placed over the upper slide, which helped in forming a uniform thin layer. The weight was removed, and excess adhering gel was wiped. After that 20 g weight was coupled carefully to upper slide. Time taken to travel a distance of 7.5 cm by upper slide under the influence of weight was recorded. The following formula was used to determine spreadability.

S = M x L / T

Where, S - Spreadability  M - Weight coupled to the upper slide (20 g)  L - Length of the glass slide (7.5 cm)  T- Time is taken to separate the slides in seconds ¹⁹.

Drug Content: The drug content of the gel was determined by dissolving 0.5 g of the gel in 50 ml of phosphate buffer pH 7.4. The solution was diluted with phosphate buffer pH 7.4 and filtered through a 0.45 µm membrane filter. Absorbance was measured using Shimadzu1800 UV visible spectrophotometer ¹⁵.

In-vitro Drug Release Study: Franz diffusion cell was used for in vitro drug release studies having a receptor compartment capacity of 22.6 ml and an effective diffusion area of 4.52 cm². The cellophane membrane of the required thickness was hydrated for 24 hours before use with phosphate buffer pH 7.4. The donor compartment contained 1 g gel, and the recipient compartment contained phosphate buffer pH 7.4. The whole assembly was fixed on a magnetic stirrer, and the solutions in the receptor compartment were continuously stirred using magnetic beads at 50 rpm, and the temperature was maintained at 35±0.5 °C. At regular intervals, sampling was done from the receptor compartment, and an equal volume of fresh phosphate buffer pH 7.4 was added to the receptor compartment. The spectrophotometric method measured the active ingredient contained in the collected sample. The cumulative percentage of drug release was plotted against time ¹⁵.

Optimization of Formulation: Optimization of the formulation was done by the software Design Expert 6.0.8 Portable.

Accelerated Stability Study: Accelerated stability study was conducted for optimized gel at 40°C and 75% RH for three months using a humidity chamber. The gel was analyzed for pH, viscosity, and drug content ²⁰.

RESULTS AND DISCUSSION:

Drug Excipients Compatibility Study using FTIR: IR studies have identified key functional group IR bands of pure drugs and physical mixtures and studied the physical and chemical interactions between drugs and the excipients used.

FIG. 1(A): IR SPECTRA OF MIXTURE OF DRUGS; 1(B): IR SPECTRA OF MIXTURE OF DRUGS AND POLYMER

It has been observed that the IR band of the characteristic drug remains unchanged in the IR spectrum of the physical mixture of drug and polymer. IR analysis showed that the drug and polymer are compatible Fig. 1A, 1B.

Screening of Polymers: All preliminary trial batches of gel show viscosity variation ranging from 800 to 190000 cps.

The pH values of all prepared formulations range from 6 to 7, which are considered acceptable to avoid the risk of irritation upon application to the skin. Of the five polymers, batch F2 showed optimum viscosity, good clarity, and homogeneity. Therefore, carbopol 934 was chosen for optimization Results of preliminary trial batches of herbal gel is shown in Table 4.

TABLE 4: RESULTS OF PRELIMINARY TRIAL BATCHES OF HERBAL GEL FOR SCREENING OF POLYMERS

-Not satisfactory, + satisfactory, ++good, +++very good

Evaluation of 3² full Factorial Design Batches of Herbal Gel: The factorial design batches were evaluated for viscosity, homogeneity, pH, spreadability, drug content, and cumulative % drug release at 8 hrs Results of 3² full factorial design batches of herbal gel is shown in Table 5, 6.

TABLE 5: RESULTS OF 3² FULL FACTORIAL DESIGN BATCHES OF HERBAL GEL

TABLE 6: EXPERIMENTAL RUNS AND MEASURED RESPONSES OF 3² FULL FACTORIAL DESIGN BATCHES OF HERBAL GEL

FIG. 2: CUMULATIVE PERCENTAGE RELEASE OF QUERCETIN AT 8 HRS

FIG. 3: CUMULATIVE PERCENTAGE RELEASE OF BERBERINE HCL AT 8 HRS

FIG. 4: CUMULATIVE PERCENTAGE RELEASE OF CURCUMINOIDS AT 8 HRS

Regression Analysis:

Regression Analysis for the Effect of X₁ and X₂ on Y₁ (Viscosity): The higher values of correlation coefficients for viscosity indicate a good fit. Here p Value for X₁ and X₂ was less than 0.05. Therefore, Carbopol 934 and propylene glycol significantly affected viscosity Results for regression statistics Y₁ is shown in Table 7. From the 3D surface plot Fig. 5 and regression coefficient values of factors, it was concluded that carbopol 934 and propylene glycol positively affected viscosity. Here the b₂ value is more positive than the b₁ value, indicating that viscosity increases with increasing amounts of propylene glycol compared to carbopol 934 ^{21, 22, 23}.

FIG. 5: 3D SURFACE PLOT OF RESPONSE Y₁

TABLE 7: REGRESSION STATISTICS Y₁

Full model equation Y₁=75094.38+ 24466.83X₁+26949.17X₂

Regression Analysis for the Effect of X₁ and X₂ on Y₂ (Cumulative Percentage Release of Quercetin at 8 hrs): The higher values of correlation coefficients for drug release at 8 hrs indicate a good fit. Here, the p-values for X₁ and X₂ were less than 0.05. Therefore, carbopol 934 and propylene glycol significantly affected in-vitro drug release at 8 hrs Results for regression statistics Y₂ is shown in Table 8.

From the 3D surface plot Fig. 6 and regression coefficient values of factors, it was concluded that carbopol 934 had a negative effect on in vitro drug release and propylene glycol had a positive effect on in vitro drug release, so it was concluded that % drug release decreased with increasing concentration of carbopol 934 and increased with increasing concentration of propylene glycol. The significance levels for the X₁² and X₁X₂ coefficients were P= 0.1851and 0.2188, respectively, so they were omitted from the full model to generate a reduced model. The coefficients X₁, X_2, and X₂² were significant at P<0.05; therefore, they were retained in the reduced models ^{21, 22, 23}.

FIG. 6: 3D SURFACE PLOT OF RESPONSE Y₂

TABLE 8: REGRESSION STATISTICS Y₂

Full model equation Y₂= 78.40-7.28X₁+10.43X₂+0.81X₁²- 9.17X₂² -0.61X₁X₂

Regression Analysis for the Effect of X₁ and X₂ on Y₃ (Cumulative percentage Release of Berberine HCl at 8 hrs): The higher values of correlation coefficients for drug release at 8 hrs indicate a good fit.

Reduced model equation on the basis of p value

Y₂=78.40- 7.28X1+10.43X2-9.17X22

Here p Value for X₁ and X₂ was less than 0.05. Therefore, carbopol 934 and propylene glycol significantly affected in-vitro drug release at 8 hrs Results for regression statistics Y₃ is shown in Table 9. From the 3D surface plot Fig. 7 and regression coefficient values of factors, it was concluded that carbopol 934 had a negative effect on in-vitro drug release and propylene glycol had a positive effect on in-vitro drug release, so it was concluded that % drug release decreased with increasing concentration of carbopol 934 and increased with increasing concentration of propylene glycol. The significance levels of the coefficients X₁² and X₁X₂ were P= 0.8817and 0.2458, respectively, so they were omitted from the full model to generate a reduced model. The coefficients X₁, X_2, and X₂² were significant at P<0.05; therefore, they were retained in the reduced models ^{21, 22, 23}.

Reduced model equation based on the p-value

Y₃= 32.20-3.31 X₁+3.94 X₂-2.37 X₂²

FIG. 7: 3D SURFACE PLOT OF RESPONSE Y₃

TABLE 9: REGRESSION STATISTICS Y₃

Full model equation Y₃= 32.20-3.31 X₁+3.94X₂+0.035X₁²-2.37X₂²-0.24 X₁X₂

Regression Analysis for the Effect of X₁ and X₂ on Y₄ (Cumulative Percentage Release of Curcuminoids at 8 hrs): The higher values of correlation coefficients for drug release at 8 hrs indicate a good fit.

Here p Value for X₁ and X₂ was less than 0.05. Therefore, carbopol 934 and propylene glycol significantly affected in-vitro drug release at 8 hrs Results for regression statistics Y₄ is shown in Table 10.

From the 3D surface plot Fig. 8 and regression coefficient values of factors, it was concluded that carbopol 934 had a negative effect on in-vitro drug release and propylene glycol had a positive effect on in-vitro drug release, so it was concluded that % drug release decreased with increase in the concentration of carbopol 934 and increased with increasing concentration of propylene glycol. The significance levels of the coefficients X₁₂ and X₁X₂ were P= 0.6123 and 0.0736, respectively, so they were omitted from the full model to generate a reduced model. The coefficients X₁, X₂, and X₂₂ were significant at P<0.05; therefore, they were retained in the reduced models ^{21, 22, 23}.

Reduced model equation based on a p-value

Y₄= 61.23-5.86 X₁+7.03 X₂ -5.32 X₂²

FIG. 8: 3D SURFACE PLOT OF RESPONSE Y₄

TABLE 10: REGRESSION STATISTICS Y₄

Full model equation Y₄ = 61.23-5.86X₁ + 7.03X₂ + 0.15 X₁²-5.32 X₂²-0.49 X₁X₂

Optimization of Formulation: The optimum formulation was chosen based on the criteria of minimum & maximum values of the response variables. From Fig. 9, we can conclude that the batch with X₁ = 0.79 and X₂ =14.60 was selected as the optimized batch with desirability 1.

TABLE 11: RESULTS OF EVALUATION PARAMETERS OF OPTIMIZED BATCH (D0)

FIG. 9: OPTIMIZED BATCH FROM OVERLAY PLOT

TABLE 12: COMPARISON BETWEEN RESPONSES OF OPTIMIZED BATCH (D0)

The actual response of the optimized batch was measured and compared with the predicted response of the checkpoint batch, and % Error was found to be less than 5%. So it shows a good correlation between observed and predicted values. Hence it was concluded that this design was valid.

TABLE 13: ACCELERATED STABILITY STUDY OF GEL FORMULATION

This study showed that drugs remained stable in gel formulation at accelerated conditions for 90 days. No significant variations in pH, viscosity, % drug content and cumulative percent drug release at 8 hrs were observed at mentioned conditions.

CONCLUSION: The present investigation was to develop, optimize and evaluate herbal gel formulation using polymers such as carbopol 934 and propylene glycol. An FTIR investigation of drug excipient compatibility revealed no interactions between drugs and excipients. From all parameters and experimental design evaluation, it was concluded that viscosity increased with increasing carbopol 934 and propylene glycol concentrations; cumulative percent drug release decreased with increasing carbopol 934 concentrations and increased with increasing propylene glycol concentrations.

ACKNOWLEDGEMENT: Nil

CONFLICTS OF INTEREST: The authors declare no conflict of interest.

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    How to cite this article:

    Patel K and Zaveri M: Development, optimization and evaluation of herbal gel formulation. Int J Pharm Sci & Res 2023; 14(3): 1491-99. doi: 10.13040/IJPSR.0975-8232.14(3).1491-99.

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