INTRODUCTION:

Halitosis is a condition characterized by an unpleasant odor, which can result from either oral or non-oral disorders¹. Subsequently, oral disorders, accounting for the majority of halitosis cases, include periodontal disease, oral infection, mucosal ulceration, etc. The formation of dental caries, which can serve as the precursor to halitosis, may occur due to the presence of gram-negative anaerobes such as S. mutans, a common component of the mouth normal flora^3,4. Therefore, inhibition of S. mutans growth is believed to play a role in inhibiting and helping overcome bad breath.

Oral Thin Film (OTF) is one of film-shaped preparations developed as an alternative to conventional forms, aiming to improve drug administration for patients. The rapid solubility of these film preparations in the oral cavity can increase the optimization of drug use. The development of OTF preparations has been widely carried out not only for synthetic drugs like zolpidem⁵ or flurbiprofen⁶, but also for herbal medicine⁷. The development of OTF with extracts to treat halitosis that have been carried out include using durian peel⁸, red dragon fruit peel extract⁹, betel leaves extract¹⁰, or Matricia chamomille extract¹¹, etc.

Various polymers have been used in the development of oral film preparations such as gelatin, HPMC, CMC, Starch, etc. The use of hydrophilic polymers either single or in combination, natural or synthetic polymers has been widely examined and greatly determines the physical properties of the resulting film¹². The use of the right polymer will produce oral film preparations that are flexible, easy to use, resistant to moisture, and also do not easily stick to the fingers when used^13,14.

Cymbopogon citratus (DC). Stapf. (C. citratus), commonly known as lemongrass is one of the herbal medicines that is popularly used in traditional practices. The phytochemical content of this plant has been studied and can be used in medicine. The flavonoid content of lemon grass leaves infusion has long been used as an inflammatory health drink¹⁵. Numerous studies documented the pharmacological activities of lemongrass, including antidiarrheal¹⁶, antibacterial^{17, 18,19}, antifungal²⁰, antimutagenic activity²¹ or anti-inflammatory properties²².

This study aimed to optimize the effect of variations in gelatin, HPMC, and corn starch in OTF preparation containing ethanol extract of C. citratus. The physical characterization, stability and antibacterial evaluation were conducted to examine whether the resulting OTF preparation can be an alternative to eliminating bad breath.

MATERIAL AND METHODS:

Materials:

C. citratus was obtained from a local farmer in Tarutung, North Sumatera, Indonesia. Gelatin was obtained from Sigma Aldrich. HPMC, corn starch, glycerin, citric acid, menthol, sucralose, natrium benzoate, and distilled water were obtained from Smart Chemical Lab, Indonesia. All other chemicals and reagents were of analytical grades.

Plant Identification:

The plant sample was identified as C. citratus in Herbarium Medanense, Faculty of Mathematics and Science, Universitas Sumatera Utara, Indonesia, with identification Number 154/MEDA/2022.

Extract Preparation:

Leaf samples were cleaned of impurities, then dried and mashed with a mixer until the sample became powder, which was extracted using the maceration method with 96% ethanol until a thick extract was produced.

Phytochemical Screening:

The screening was carried out based on Reveny, et all (2023) on the dried sample and extract to evaluate the presence of alkaloid, tannin, phenolic compound, glycosides, terpen, and saponin²³.

OTF Preparation:

Film was produced using the solvent casting method, while starch and gelatin were dissolved with hot distilled water and stirred at 500rpm until clear. HPMC was developed with hot water and allowed to become mesa gel, and starch, gelatin, and HPMC were then mixed until homogeneous. Essential oil, sucralose, and menthol were added and stirred until homogeneous, the solution was added to the extract slowly put into a mold, and dried using a dehydrator at 40±2°C for 24hours.

Table 1: OTF formula contained an extract of C. citratus

Materials	Formula (%)
Materials	F1	F2	F3	F4	F5
Extract	0.5	0.5	0.5	0.5	0.5
Corn starch	0	1.25	2.5	3.75	5
HPMC	5	3.75	2.5	1.25	0
Gelatin	3	3	3	3	3
Glycerin	2	2	2	2	2
Citric Acid	0.1	0.1	0.1	0.1	0.1
Menthol	0.1	0.1	0.1	0.1	0.1
Sucralose	1	1	1	1	1
Natrium Benzoate	0.1	0.1	0.1	0.1	0.1
Essential oil	q.s	q.s	q.s	q.s	q.s
Distilled water adds	100	100	100	100	100

Film Evaluation:

Organoleptic:

Organoleptic test was conducted by visual method to access the homogeneity, textures, color, and taste of film, and the effect of polymer variation was observed on this parameter²³.

Weight Variability Test:

Weight variability of film was observed using an analytical balance, and six films were weighed for each formula to get the mean and SD value²⁴.

Thickness Tests:

Five parts of film such as top right, top left, bottom right, bottom left, and center were measured using a caliper (Mitutoyo, Japan) to obtain the mean and SD value²⁵.

pH Determination:

A pH Meter (Hanna) was used to evaluate the surface pH of films, and the calibration procedure using standard buffer solution at pH 4 and 7 was conducted before the measurement was carried out. A piece of film was rinsed with 10ml distilled water for more than 30 seconds, then the electrode was put into the beaker to measure pH⁹.

Folding Endurance Test:

Folding endurance test included folding a 2x3cm film repeatedly on the same part until it breaks. Six sheets of film were subjected to this process to determine the durability and resistance to folding. The number of folds obtained until film was broken becomes the value of folding endurance film²⁶.

Colorimeter Studies:

The color test was carried out to evaluate the influence of the polymer on the color of film, and the test was conducted using a colorimeter WR10 (FRU, China). The parameters such as L (lightness), a* (redness/greenness) and b (yellowness/blueness) were evaluated at least triplicate for each film²⁷.

Disintegration Time:

The test was conducted based on Tamer, 2018, by slight modification, by embedding film into a petri dish containing 15ml distilled water. The petri dish was shaken persistently until film started to crumble/break. All considered were performed in triplicate for each film²⁸.

Stability Test:

Stability test was conducted by keeping film at 25±2^oC and 40±2^oC for 3 months. The evaluation was conducted every 2 weeks on organoleptic and pH of film.

Antibacterial Test:

The antibacterial test was conducted following the method outlined by Nabila (2024), which involves placing 0.1ml of bacterial inoculum into a sterile petri dish. Subsequently, 15ml of Mueller Hinton agar media at 45-50℃ was poured into the dish, and the container was shaken on the table surface to ensure that the media and bacterial suspension were blended homogeneously. Once the media solidified, circular films were placed on top and incubated at 35±2℃ for 24 hours. The inhibition zone was calculated to measure the activity of film against S. mutans⁹.

RESULT AND DISCUSSION:

Before film preparation, both the powder and extract of C. citratus underwent phytochemical screening to determine the constituents. The results of phytochemical screening are presented in Table 2 and indicate the presence of C. citratus contained alkaloids, tannins, glycosides, saponins, flavonoids, and steroids in both the powder and ethanol extract.

Table 2: The result of Screening phytochemical for powder an extract of C. citratus

Active compound	Powder	Extract
Alkaloids	Present	Present
Tannins	Present	Present
Glycosides	Present	Present
Saponin	Present	Present
Flavonoids	Present	Present
Steroids	Present	Present

Organoleptic Evaluation:

The results of all formulas showed good homogeneity and a thin texture. Different polymer variations resulted in films of varying colors, with F2 exhibiting a greenish-brown color, progressing to the darkest shade observed in F1, which showed a dark greenish-brown color. All films gave a peppermint and sweet taste but were slightly sticky and gave a fresh effect. The figure of film can be seen in Fig. 1 and the organoleptic characterization can be seen in Table 3.

Fig. 1: OTF contained C. citrate at different polymer composition

Weight Variability:

Based on the data (Table 3), the composition of the polymer largely determines the weight of the resulting film. The use of gelatin and corn starch polymer (F5) produced the thinnest film compared to the others, and the use of corn starch and HPMC variations with a ratio of 1:3 (F2) or 3:1 (F4) produced films with almost the same weight variation. The variation of HPMC: corn starch (1:1) produced a thicker weight, and HPMC: gelatin (5:3) produced the thickest film among other formulas. However, the variation of film weight produced for all formulas showed good uniformity results.

Thickness Evaluation:

Thickness of films produced from various formulations of film-forming polymers did not show any significant difference, except for F1, which did not contain corn starch. Films from F1 were noticeably thicker compared to those from other formulas.

pH Determination:

pH of the formula was in the range of 6.12 to 6.36 (Table 3), and the optimum pH of the oral dosage form was noted to be near the normal pH of saliva (5.9 to 7.1). The reason for this is that an acidic pH can potentially lead to irritation if it becomes too acidic, whereas an overly alkaline pH may contribute to dental caries²⁹.

Folding Endurance:

The mechanical and flexibility of films were evaluated using folding endurance test. Film is considered to have excellent flexibility if it does not break until subjected to more than 300 folds^30,31. The data showed that all films have good flexibility and folding resistance, and film using 3% gelatin and HPMC:Corn starch (0:5) has the highest value compared to the others. A high amylose ingredient (±25%) from corn starch influences film-forming capacity and produces a strong film. The use of glycerin as a plasticizer also has the function of increasing film flexibility and preventing film preparation from breaking or tearing, thereby increasing folding durability of film preparation³².

Table 3: The physical characterization of OTF

Formula	Weight variability (g)	Thickness (mm)	pH	Folding endurance (times)
F1	0.663 ± 0.06	0.341 ± 0.008	6.32 ± 0.032	391.83 ± 26.29
F2	0.328 ± 0.01	0.256 ± 0.016	6.15 ± 0.048	523.83 ± 32.57
F3	0.403 ± 0.03	0.246 ± 0.017	6.17 ± 0.014	560.50 ± 24.62
F4	0.333 ± 0.06	0.250 ± 0.018	6.12 ± 0.015	339.67 ± 11.13
F5	0.245 ± 0.04	0.224 ± 0.009	6.36 ± 0.019	579.50 ± 19.72

Data expressed in mean± SD, n=3

Colorimeter Assesment:

Color test testing was carried out to evaluate the effect of the polymer combination used on the color of OTF preparation produced. L* test data is an indicator of the level of brightness where a value of 0 means black and 100 tends to be white. The data indicates that F2 to F5 exhibit similar colors, ranging from 70 to 75, suggesting brightness, whereas F1 has a lower value of 60.31, indicating a darker color spectrum compared to other formulas. While a * value shows a color spectrum that tends to be reddish (if the value is negative 0-80) or greenish (if the value is positive 0-80). The test results indicate that the values of the five formulas are not significantly different and are positive, suggesting that all five formulas tend to exhibit a slightly greenish color. The test on the b* value shows a positive value, indicating that all formulas tend to exhibit a yellowish color. If the b* value tends to be positive, the color tends to be yellowish, while if it is negative, it tends to have a blue color³³.

Table 4: The result of the colorimeter test and disintegration time of films

Formula	L*	a*	b*	Disintegration time (s)**
F1	60.31	5.66	20.92	105 ± 6
F2	71.50	4.49	20.79	75 ± 3
F3	72.68	3.04	19.90	60 ± 2
F4	73.91	4.16	19.50	74 ± 4
F5	72.98	4.09	21.53	100 ± 3

**Data expressed in mean± SD, n=3

Disintegration Time:

Disintegration time testing for films was obtained in the range of 60 to 105 seconds. The use of corn starch and HPMC variation (1:1) in F3 produced films with the fastest disintegration rate compared to other formulas. Various factors can affect disintegration time of film preparations such as the hydrophilic properties of the polymers used, where the combination of polymers with various properties will affect the characteristics of the resulting film, specifically disintegration time of film³⁴.

Stability Test:

Stability test is a very important test carried out to ascertain whether the quality of the resulting film preparation is as expected. Stability test in this study was carried out at room temperature (25±2^oC) and high temperature (40±2^oC). Based on the parameters observed on film weight for 3 months, it was found that F4 and F5 had better stability than other formulas. Storage at 40°C showed a decrease in film weight that was significantly different in F1, F2, and F3 (Fig. 2 and 3). In pH stability, it was found that all pH film preparations during 3 months storage both at room temperature and high temperature showed good stability, although there was a slight decrease, the changes were very small and still in the safe range for preparations given by mouth (Fig. 4 and 5). In folding endurance evaluation, storing film at room temperature resulted in a decrease in folding endurance value for F3, while other formulas did not exhibit a significant decrease (Fig. 6 and 7). However, storing films at high temperature for 3 months resulted in a significant decrease in folding endurance ability for all formulas, with each formula experiencing a substantial decline. This indicates that film preparations made are not suitable for storage at temperatures above room temperature. One reason for the decrease in film flexibility is the thermosensitive nature of the gelatin polymer used in the formulation. At temperatures around 36°C, the gelatin structure begins to transition from a helical to a coiled form, eventually liquefying. This structural change can compromise the integrity and flexibility of film³⁵.

Fig. 2: Weight stability of OTF after 3 months at 25^oC. (Data was expressed in means, n=3)

Fig. 3: Weight stability of OTF after 3 months at 40^oC. (Data was expressed in means, n=3)

Fig. 4: pH of OTF after 3 months at 40^oC. (Data was expressed in means, n=3)

Fig. 5: pH of OTF after 3 months at 40^oC. (Data was expressed in means, n=3)

Fig. 6: Folding endurance of OTF after 3 months at 40^oC. (Data was expressed in means, n=3)

Fig. 7: Folding endurance of OTF after 3 months at 40^oC. (Data was expressed in means, n=3)

Antibacterial Test:

Antibacterial activity test carried out showed that the 0.5% extract in OTF preparation provided the ability of a weak antibacterial effect against S. mutans. The diameter of the inhibition zone produced for each formula for F1-F5 was 6.5±0.17mm, 8.4±1.10mm, 8.3±0.55mm, 8.7±0.74mm, 8.1±0.95mm, and 7.8±0.51 mm, respectively. The obtained zone of inhibition was still relatively low, indicating a need to increase the concentration of the extract used to enhance antibacterial activity.

CONCLUSION:

In conclusion, oral strip film preparations were successfully produced and showed good physical characteristics. Subsequently, F5 showed the best stability study in the storage of the preparation at room temperature and high temperature, but there was a slight decrease in folding endurance value at 40^oC. Antibacterial activity test showed that the preparation of 0.5% extract in film preparation showed a weak antibacterial effect against S. mutans.

ACKNOWLEDGEMENTS:

This research was funded by Universitas Sumatera Utara in accordance with the contract of TALENTA research implementation with contract number 77/UN5.2.3.1/PPM/KP-TALENTA/2022, on August 09 2022.

CONFLICT OF INTEREST:

Authors have declared no conflict of interest to declare.

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Received on 01.04.2024 Revised on 15.07.2024

Accepted on 16.09.2024 Published on 10.04.2025

Available online from April 12, 2025

Research J. Pharmacy and Technology. 2025;18(4):1474-1480.

DOI: 10.52711/0974-360X.2025.00211

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Creative Commons License.

Parameter	Formula
Parameter	F1	F2	F3	F4	F5
Homogeneity	Homogenous
Texture	Thick, wet, and sticky	Smooth, thin, and plastic	Smooth, thin, and slightly sticky	Smooth, thin, and plastic	smooth, thin, and plastic
Color	Dark greenish brown	Greenish brown	Greenish brown	Greenish brown	Greenish brown
Aroma	Peppermint
Taste	Sweet, slightly bitter, fresh sensation