Development and Evaluation of Mucoadhesive Buccal Films of Lacidipine Utilizing Sterculia foetida Gum as a Natural Polymer

Jeel Mehta, Bharat S. Pithiya*, Dhara A. Chavda

Shree H. N. Shukla Institute of Pharmaceutical Education & Research, Rajkot, Gujarat, India.

*Corresponding Author E-mail: pithiyabs211@gmail.com

ABSTRACT:

This study aimed to develop and evaluate mucoadhesive buccal films of Lacidipine employing Sterculia foetida gum as a natural polymer. The gum was extracted from the tree’s trunk and branches and characterized for its physicochemical properties. Lacidipine was identified and confirmed using UV-visible spectrophotometry, while compatibility with the polymer was assessed through FTIR and DSC analysis. Buccal films were prepared using the solvent casting method with varying polymer ratios and evaluated for parameters such as thickness, weight uniformity, folding endurance, swelling index, surface pH, drug content, scanning electron microscopy (SEM), ex vivo bioadhesive strength, in vitro drug diffusion, drug release kinetics, and stability under accelerated conditions. Among all formulations, the F5 batch, comprising Sterculia foetida gum and sodium alginate in a 3:4 ratio, exhibited optimal characteristics, including high folding endurance, consistent drug content, strong mucoadhesion, and prolonged drug release over 12hours. The bioadhesive strength increased proportionally with the concentration of Sterculia foetida gum, confirming its utility as a mucoadhesive agent. These findings suggest that Sterculia foetida gum is a promising natural polymer for buccal drug delivery systems, enhancing the bioavailability of drugs like Lacidipine with poor oral bioavailability and short half-life.

KEYWORDS: Sterculia Foetida, Mucoadhesive Films, Buccal Drug Delivery, Lacidipine, Natural Polymer, Sustained Release.

INTRODUCTION:

The oral route remains the most widely preferred method for drug administration due to its convenience, patient compliance, and flexible formulation options.^1-2 However, alternative mucosal routes—such as buccal, nasal, rectal, and vaginal—offer distinct pharmacokinetic advantages by bypassing hepatic first-pass metabolism and enabling rapid systemic drug absorption.^3–6

Among these, the buccal route is particularly suitable for the delivery of macromolecules, unstable proteins, and hydrophilic drugs that are poorly absorbed via the gastrointestinal tract. Direct access to the bloodstream is provided by buccal drug delivery through the rich vascularization of the cheek mucosa and avoids enzymatic degradation in the GI tract. However, the limited residence time of formulations on the buccal mucosa necessitates the use of mucoadhesive systems to prolong contact duration and improve therapeutic efficacy.^7-9

Mucoadhesive drug delivery systems rely on specialized polymers that adhere to mucosal tissues, enhancing the residence time of the drug at the site of absorption. These systems improve bioavailability, provide controlled and sustained release, and are particularly advantageous for patients who face difficulties swallowing conventional tablets or capsules.^10-13

Lacidipine is a dihydropyridine calcium channel blocker characterized by high lipophilicity and a slow onset of action. It is commonly used in the treatment of hypertension and provides long-term control of blood pressure without inducing reflex tachycardia. Still, because of its significant first-pass metabolism and limited water solubility, lacidipine has a low oral bioavailability necessitating the development of alternative delivery systems to overcome these limitations.^14-15

Natural polymers such as plant-derived gums and mucilages are increasingly being utilized in pharmaceutical formulations owing to their biodegradability, biocompatibility, non-toxicity, and cost-effectiveness. Sterculia foetida gum, a hydrophilic polymer obtained from the trunk and branches of the tree, has shown promise as a mucoadhesive agent. Its ability to swell and form gels in aqueous environments makes it suitable for use in controlled release formulations.^16–21

Literature review revealed that similar work has been carried out on various drugs employing natural polymers for buccal film formulations, which consistently showed enhanced mucoadhesion, prolonged residence time, and better therapeutic performance.^22-25 In this study, buccal films of Lacidipine were formulated using Sterculia foetida gum, alone and in combination with other polymers, to develop a mucoadhesive delivery system aimed at improving the drug’s bioavailability and therapeutic performance.

MATERIALS AND METHODS:

Acidipine was obtained as a gift sample from Unichem Laboratories Ltd., Maharashtra, India. Sterculia foetida gum (Family: Sterculiaceae) was collected from the trunk and branches of the tree and authenticated using macroscopic and microscopic characteristics. The authenticated gum was purified and used in formulation development.

Optimization of polymer ratios:

A total of approximately 50 experimental formulations were developed utilizing Sterculia foetida gum in combination with various polymers, including Carbopol-940, HPMC, HEC, PVP, gelatin, pectin, sodium alginate, and PVA. The influence of different concentrations of the plasticizer PEG-400 and the permeation enhancer DMSO was also assessed. From these trials, nine formulations demonstrated favorable outcomes—comprising three each based on pectin (F1–F3), sodium alginate (F4–F6), and PVA (F7–F9)—and were subsequently chosen for further investigation (Table 1).

Development of Mucoadhesive Buccal Patches via Solvent Casting Approach:

A measured quantity of Sterculia foetida gum was dispersed in distilled water and stirred continuously at 500 rpm to obtain a homogenous solution. According to the formulation design, specific ratios of secondary polymers (pectin, sodium alginate, or PVA) were added to the base gum solution to prepare nine distinct formulations (F1 to F9).

The excipients—sucrose, vanillin, PEG-400, and DMSO were incorporated sequentially as per the composition table. Lacidipine was then added to each mixture. The resulting solutions were spread uniformly in Petri dishes of uniform diameter and dried either at ambient temperature (under mesh protection) or in a hot air oven at 30±5°C until non-tacky, flexible films were formed.

Table 1: Composition of Lacidipine buccal film formulations (F1–F9)

Formulation	F1	F2	F3	F4	F5	F6	F7	F8	F9 Code
Ingredients	(in mg)
Lacidipine	2.74	2.74	2.74	2.74	2.74	2.74	2.74	2.74	2.74
*Sterculia Foetida gum*	200	300	400	200	300	400	200	300	400
Pectin	500	400	300
Sodium alginate				500	400	300
PVA							500	400	300
Vanillin	60	60	60	60	60	60	60	60	60
Sucrose	300	300	300	300	300	300	300	300	300
	(in ml)
Water	10	10	10	10	10	10	10	10	10
PEG	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5
DMSO	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0

Evaluation of Lacidipine films:

1. Thickness Measurement: Film thickness was measured at five distinct points using a digital micrometer, and the mean±standard deviation was calculated.

2. Weight Variation: From every formulation batch, five films were taken and individually measured for weight. The average weight and standard deviation were recorded to assess uniformity.

3. Folding Endurance: A single patch was repeatedly folded at the same site until it broke. The number of folds before tearing was recorded.

4. Swelling index: Each patch was placed in a pre-weighed mesh basket and immersed in 4mL phosphate-buffered saline (PBS, pH 6.8) for 10 minutes. The swelling index was calculated as: Dividing the Difference Between the Final and Initial Weights of the Film By Its Initial Weight.

5. Surface Ph: Films were moistened with 1mL deionized water and equilibrated for 30minutes. Surface pH was measured with a digital pH meter in triplicate.

6. Drug Content Assay: Each buccal film was dissolved in 50mL of phosphate buffer solution (pH 6.8), subjected to sonication, and the volume was adjusted to 100mL. The resulting solution was filtered, and a 1mL aliquot was further diluted to 100 mL. The final solution was then analyzed using UV-Visible spectrophotometry at 284nm to quantify the Lacidipine content.

7. Surface Morphology (SEM Analysis): Surface characteristics, including morphology, porosity, and film uniformity, were assessed using scanning electron microscopy (SEM).

8. Ex Vivo Bioadhesive Strength: Bioadhesive strength was measured using a modified double-arm balance. Fresh porcine buccal mucosa was used as the biological surface. A 5g preload was applied for 3 minutes before incremental weights were added until detachment occurred.

Force (N) = Weight × 9.81 / 1000

9. In Vitro Drug Diffusion Study: Franz diffusion cells were used with PBS (pH 6.8) as the receptor medium at 37±1°C. A cellulose nitrate membrane separated the donor and receptor chambers. Aliquots (1mL) were withdrawn at predetermined intervals and analyzed at 284nm.

10. Stability Studies: Accelerated stability testing of the optimized formulation (F5) was conducted as per ICH guidelines at 40±2°C and 75±5% relative humidity for a period of 30 days. After the storage period, the buccal films were assessed for parameters such as physical appearance, film thickness, drug content, surface pH, swelling behavior, and in vitro release profile.

RESULTS AND DISCUSSION:

All nine film formulations (F1–F9) were effectively made by using the solvent casting method. The resulting patches were uniform, smooth, and free of phase separation. The use of both ambient and oven drying conditions produced comparable film quality. PVA-based films (F7–F9) displayed the highest flexibility, while pectin-based films (F1–F3) were slightly brittle. The addition of PEG-400 improved film pliability and handling across all batches.

Figure 1: Visual appearance of Lacidipine buccal film formulations

Evaluation of Physico-Chemical Properties:

Results of all formulations (Table 2) confirmed acceptable ranges for key parameters. Film thickness varied between 0.6882±0.02mm and 0.7358±0.02mm. The patch weights ranged from 345.4±4.21mg to 405.8±3.77mg, with minimal intra-batch variability.

Folding endurance ranged from 63(F3) to 105(F5), suggesting enhanced flexibility due to optimal polymer blending in F5. Swelling index was highest in F5 (4.1057), indicating superior hydration capacity and mucoadhesive potential. Surface pH (6.05 to 7.10) was close to the physiological salivary pH, reducing mucosal irritation risk. Drug content was consistent (93.6% to 100.5%), indicating good uniformity.

Table 2: Physicochemical properties of Lacidipine buccal films (F1–F9)

Formulation code	Thickness	Weight variation	Folding endurance	Swelling index	Surface pH	Bioadhesion strength (N)	Drug content assay (%)
F1	0.6882 ± 0.02	405.8±3.77	65	2.2125	6.80±0.10	0.0283	97.6
F2	0.6978 ± 0.01	383.6±4.39	72	2.6279	6.52±0.08	0.0292	94.02
F3	0.7152 ± 0.06	390.6±3.84	63	2.5152	6.50±0.34	0.0288	94.7
F4	0.7190 ± 0.09	345.4±4.21	96	3.5909	7.04±0.09	0.0356	95.2
F5	0.7358 ± 0.02	350.2±4.32	105	4.1057	6.84±0.06	0.0395	96.8
F6	0.7258 ± 0.02	364.2±3.11	98	4.0667	6.05±0.11	0.039	93.6
F7	0.6912 ± 0.03	369.8±3.11	66	2.5455	7.10±0.13	0.0287	99.6
F8	0.6978 ± 0.01	374.6±3.28	80	2.6154	7.06±0.09	0.0244	100.5
F9	0.7160 ± 0.09	383.8±5.05	68	2.3571	6.09±0.04	0.0271	96.5

Table 3: In vitro drug release profile of Lacidipine buccal films over 12 hours

Sr. No	Time (hr.)	Cumulative percentage release %
Sr. No	Time (hr.)	Fl	F2	F3	F4	F5	F6	F7	F8	F9
1	0	0	0	0	0	0	0	0	0	0
2	0.5	10.2	11.1	10.1	11.0	13.9	13.7	12.3	13	12.7
3	1	18.4	19.5	19.0	17.2	20.8	18.9	17.8	19.2	18.5
4	2	31.7	34.8	33.6	36.1	37.7	36.9	34.2	36.1	34.8
5	4	49.7	50.2	49.4	48.3	53.9	51.8	46.7	48.9	47.5
6	6	61.7	63.4	62.1	59.6	63.7	62.9	58.J	59.6	58.9
7	8	69.5	70.9	69.8	71.6	72.9	71.8	69.2	71.8	70.9
8	10	75.0	76.0	77.3	76.7	79.5	78.7	74.8	76.4	76
9	12	80.0	81.8	82.2	86.7	89.2	87.6	82.5	84.6	83.1

Stability Studies:

Accelerated stability testing (ICH conditions) showed no significant changes in physical or chemical properties after 30 days. F5 maintained stable drug release (89.0%), confirming formulation robustness (Table 5).

Table 5: Stability study data for optimized Lacidipine buccal film (F5) under ICH conditions

Formulation	F 5
Period	Initial	1 Month
Avg. Thickness (mm)	0.7358 ± 0.02	0.7357± 0.02
Avg. Weight (mg/cm²)	350.2 ± 4.32	350.1 ± 4.15
Folding Endurance	105	103
%Drug Content (mg/cm2)	96.8	96.59
Surface pH	6.84	6.83
Swelling Index	4.1057	4.1053
In-vitro drug release (after 12hr)	89.2	89.0
Mucoadhesive strength (g)	0.0395	0.0395

CONCLUSION:

This study successfully developed and evaluated mucoadhesive buccal films of Lacidipine using Sterculia foetida gum in combination with other polymers. Among the nine formulations, F5—composed of Sterculia foetida and sodium alginate in a 3:4 ratio—demonstrated optimal film properties including uniform thickness, excellent folding endurance, favorable surface pH, and consistent drug content. SEM analysis confirmed desirable surface morphology and porosity, while ex vivo bioadhesion and in vitro diffusion studies validated strong mucoadhesive strength and extended medication release for up to twelve hours.

A zero-order kinetic model best described the drug release behavior, with anomalous diffusion as the primary release mechanism. Accelerated stability testing confirmed the physical and chemical stability of the optimized formulation (F5) over 30 days. Overall, the findings support the potential of Sterculia foetida gum as a novel, effective natural mucoadhesive polymer for buccal drug delivery systems aimed at improving the bioavailability of poorly soluble drugs like Lacidipine.

REFERENCE:

1. Ammanage P, Rodriques A, Kempwade R, Hiremath R. Formulation and evaluation of buccal films of piroxicam co-crystals. Future J Pharm Sci. 2020; 6(1): 1.

2. Yadav BK, Khursheed AT, Singh RD. Cocrystals: A complete review on conventional and novel methods of its formation and its evaluation. Asian J Pharm Clin Res. 2019; 12(7): 68-74.

3. Gupta S, Das S, Singh A, Ghosh S. A brief review on bucco-adhesive drug delivery system. J Drug Deliv Ther. 2021; 11(4 Suppl): 231-5.

4. Bhosale NS, Gudur AS, Ramesan R, Rane DD, Arolkar PD, et al. A comprehensive review on buccal drug delivery system. Asian J Pharm Technol. 2023;13(2):139-45.

5. Aishwarya MNL, Prudhvi Raj V, Debnath S, Niranjan Babu M. A review on buccal drug delivery system. Res J Pharm Dosage Form Tech. 2017; 9(3):109-13.

6. Patel JG, Solanki SS, Patel KB, Patel MP, Patel JK. Buccal drug delivery system: a review. Res J Pharm Technol. 2012; 5(7): 883-8.

7. Rajaram DM, Laxman SD. Buccal mucoadhesive films: a review. Syst Rev Pharm. 2017; 8(1): 31.

8. Sudhakar Y, Kuotsu K, Bandyopadhyay AK. Buccal bioadhesive drug delivery—a promising option for orally less efficient drugs. J Control Release. 2006; 114(1): 15-40.

9. Pawar RR, Raut DB, Karde VK, Wadikar JC, Jadhav AS, et al. Mucoadhesive buccal drug delivery system: a review. Res J Pharm Technol. 2013; 6(5): 506-15.

10. Dixit RP, Puthli SP. Oral strip technology: overview and future potential. J Control Release. 2009; 139(2): 94-107.

11. Lee JW, Park JH, Robinson JR. Bioadhesive-based dosage forms: the next generation. J Pharm Sci. 2000; 89(7):850-66.

12. Roy S, Pal K, Anis A, Pramanik K, Prabhakar B. Polymers in mucoadhesive drug-delivery systems: a brief note. Des Monomers Polym. 2009; 12(6): 483-95.

13. Pawar RG, Pawar SD, Banerjee SK, Gadhave MV, Gaikwad DD. Novel buccoadhesive polymers: a review. Res J Pharm Technol. 2012; 5(5): 592-601.

14. McCormack PL, Wagstaff AJ. Lacidipine: a review of its use in the management of hypertension. Drugs. 2003; 63(21): 2327-56.

15. Dighe NS, Bhosale M, Gaikwad PB. An overview on estimation of lacidipine from bulk and formulation. Asian J Pharm Anal. 2021; 11(3): 223-6.

16. Lohani A, Prasad N, Arya R. Formulation and characterisation of mucoadhesive buccal films of ranitidine hydrochloride. Int J Pharm Sci Res. 2011; 2(9): 2457-62.

17. Gandhi P, Patel M, Patel K, Patel N. A review article on mucoadhesive buccal drug delivery system. Int J Pharm Res Dev. 2011; 3(5): 159-73.

18. Patel D, Patel M, Patel K, Patel N. Buccal mucosa as a route for systemic drug delivery: a review. Int J Drug Dev Res. 2012; 4(2): 99-116.

19. Tortora G, Derrickson B. Principles of anatomy and physiology. 11th ed. New York: Wiley; 2006. p.902-4.

20. Deogade U, Deshmukh V, Sakarkar D. Natural gums and mucilages in NDDS: applications and recent approaches. Int J PharmTech Res. 2012; 4(2): 799-814.

21. Kavitha M, Vadivu R, Radha R. A review on Sterculia foetida Linn. Res J Pharmacogn Phytochem. 2015; 7(4): 239-44.

22. Katnauria A, Abhishek, Choudhary H, Verma KK. Development and evaluation of mucoadhesive buccal patch of losartan potassium. Asian J Pharm Technol. 2024; 14(2): 157-62.

23. Jagdale SC, Hable AA, Kuchekar BS, Chabukswar AR. Development and evaluation of mucoadhesive buccal patches of nifedipine. Res J Pharm Technol. 2011; 4(6): 944-8.

24. Saleem MA, Pange SS, Shaikh AU, Singh VK. Development and evaluation of mucoadhesive buccal tablets of sumatriptan succinate using natural gums. Res J Pharm Technol. 2011; 4(7): 1140-6.

25. Saraf AJ, Pange S, Deshmukh S, Hajgude R. Development and evaluation of mucoadhesive buccal tablet of simvastatin. Res J Pharm Technol. 2013; 6(4): 406-14.

Received on 29.07.2025 Revised on 01.09.2025

Accepted on 27.09.2025 Published on 18.10.2025

Available online from November 03, 2025

Res. J. Pharma. Dosage Forms and Tech.2025; 17(4):262-266.

DOI: 10.52711/0975-4377.2025.00036

This work is licensed under a Creative Commons Attribution-Non Commercial-Share Alike 4.0 International License. Creative Commons License.