Formulation and Characterization of Nicotine Thin Films for Smoking Cessation through Buccal Delivery

 

Mayuri Konda^*, Krishna Mohan Chinnala, Likhitha Samineni, Yasmin Naznin, Jyothirmayee Avirneni, Kavitha Chaithanya Kondamalla.

Department of Pharmaceutics, School of Pharmacy, Nalla Narasimha Reddy Educational Society’s Group of Institutions, Hyderabad, India - 500 088.

 

ABSTRACT:

Buccal films are the promising technology with fast onset of activity. The current research was intended to prepare buccal thin films of nicotine to augment bioavailability and evade pre-systemic metabolism in smoking cessation, specifically COPD cases. Nicotine thin film was prepared using solvent casting method by using HPMC (E5, E15), PEG with varied compositions. The prepared thin films were cut into strips of area 2X2 cm² and were evaluated. Weight, thickness and surface pH were increased with decreased concentration of polymer. F5, F6, F7 have shown good folding endurance, this is due to the amalgamation of two grades of HPMC, as PEG was used at 10% concentration, Percentage elongation was constant. Moisture uptake and loss, swelling index were evaluated and variation was overlooked and % transparency was reduced due to dark colouration of extract and reduced further in case of F1 and F3. Accelerated stability studies have not revealed remarkable change in weight, disintegration time and surface pH, which indicates that temperature would not alter the properties of the thin film. From the results of drug release F5 was released 67.08% in 5 min, the total drug release was obtained in a span of 20min and F4 total drug release was obtained in 50 min with the initial release of 33% in 5min. Taking drug release profile into consideration F4 is most suitable formulation as the main objective of the study is to obtain slow release as fast release of nicotine would cause hypotension and inhibition of neurotransmission.

 

 

INTRODUCTION:

Chronic Obstructive Pulmonary Disease (COPD)

Chronic obstructive pulmonary disease (COPD) is a state in which there is inadequate airflow in to the pulmonary system. COPD is not reversible, but treatment can deliberate its advancement. Even though patients can respire in normally, changes in the minute airways source the walls being tapered during expiration, making it tough to breathe out ^[1]. In several patients with COPD, the small sacs where oxygen and carbon dioxide are exchanged are destroyed, steadily starving the body of oxygen ^[2].

 

Treatment of COPD in the course of smoking cessation

Smoking cessation is the progression of suspending tobacco smoking. Tobacco possesses addictive nicotine which makes the course of quitting often exceedingly lingering and complicated. Seventy percent of smokers would akin to quit smoking, and 50 percent account attempting to renounce within the past year. Several diverse methods can be used for smoking cessation, including quitting devoid of aid ("cold turkey" method), medications such as nicotine replacement therapy (NRT) or varenicline, and behavioral psychotherapy. The mainstream of smokers attempt to relinquish without assistance, though only 3 to 6% of suspension attempts without aid are victorious ^[3].

 

Nicotine Replacement Therapy (NRT) consist of Nicotine Patches (side effects- dermal irritation, ruddiness, tingle and rashes), Nicotine Mouth Spray (side effects- irritation of the oral cavity and gullet, augmented saliva, sickness, dyspepsia, headache and hiccups), Nicotine Lozenges (side effects- nausea, hiccups, indigestion, flatulence, wakefulness, giddiness, headache, cough, stinging throat), Nicotine Gum (side effects- Hiccups, nausea, jaw discomfort, throat irritation, increased heartbeat and gum as well attach to teeth and is not appropriate for denture users), Nicotine Inhalator (side effects- cough, irritation of oral cavity and gullet, stomach uneasiness, nausea, hiccups and sickness) and Nicotine strips (side effects- nausea, esophagus annoyance, hiccups and headache) ^[4].

Nicotine strips elucidate mild side effects which are due to immediate and fast release of the drug within 3min in to the systemic circulation, but these side effects can also be eradicated by slow release of nicotine for a prolonged period of time, this forms the key objective of the current study.

 

Buccal Thin Films

Thin-film drug delivery uses a dissolving film to release the drug buccal and sub-lingual ^[5]. A film is made by using water soluble polymers that quickly dissolves under the tongue or buccal cavity, avoiding first pass metabolism, which is very crucial for the bioavailability if Nicotine ^[6]. Thin film is similar to a postage stamp with respect to its shape and size. Thin film was developed on the basis of Transdermal Patches, which when placed at the site would release the drug into the blood circulation upon wetting by the saliva. Thin film adheres to the buccal cavity after hydrolysis by saliva which then disintegrates and dissolves for the liberation of the medicament ^[7].

 

Preparation of thin films

There are five methods for manufacturing purpose:

• Solvent casting method
• Semisolid casting method
• Hot melt extrusion method
• Solid dispersion extrusion method
• Rolling method ^[7]

 

Quick dissolving films be ideally prepared by means of method of casting solvent, whereby the hydrophilic excipients are dissolved to shape a lucid glutinous solution and the medicine along with different ingredients are dissolved in a appropriate solvent then both the solutions are mixed and stirred and lastly casted into the Petri plate and dried. The standard composition of the oral thin film formulation is mentioned in table 1 ^[3].

 

Table 1: Standard Composition of Thin Films

 

MATERIALS AND METHODS:

Materials

Nicotine was extracted from Tobacco leave in the laboratory, Nicotine standard, HPMC E5, HPMC E15 were obtained from KP Labs, Hyderabad. Ethanol, PEG, Saccharin and peppermint oil were procured from S.D Fine chemicals Ltd., Hyderabad.

 

Equipment

Weighing balance (Contech India), Vernier callipers (Edison), Disintegration apparatus (DBK Instruments), Dissolution apparatus (Lab India), UV-visible spectrometer (Elico), Hot air oven (Bio Technics India), pH apparatus (Global DPH500), Heating mantle (Bio Technics India) and FTIR (Shimadzu).

 

Nicotine extraction

Nicotine was extracted from Tobacco Leaves and the resultant dark coloured hygroscopic extract was subjected to Alkaloid chemical identification test for the confirmation.

 

Qualitative determination of Nicotine using TLC

Pre coated TLC plates are obtained and spotted by utilizing the capillary tubes; about 2cm from the perimeter, the methanol extract were applied as a solitary spot along one plane of the TLC plate for both standard and the nicotine extract. The solvent system which is chloroform-Methanol- ammonium hydroxide (60:10:1) was prepared and used as stationary phase for saturation of chamber. The TLC plates holding the sample and the standard marks were positioned in the development compartment at a 45⁰ angle covering the base of the plate by the solvent nearly up to 1 cm. The solvent face was noted and the plate was kept for drying. Since Nicotine is a white alkaloid it was detected by using Dragendorff’s reagent for means of. The R_f value is calculated by using the subsequent rule.

 

Quantitative determination of Nicotine content by UV-Vis Spectrophotometer

The nicotine standard stock solution was prepared dissolving nicotine in ethanol and distilled water. Eight standard dilutions were prepared by dilution of concentrated stock (1000mg/ml) using the concentration range of 0.2µg/ml-1.0µg/ml.

The sample extract was prepared by dissolving in ethanol and diluting by distilled water. The absorbance of the unidentified concentration was determined by plotting in the standard curve by using Microsoft excel (TREND).

 

 

Formulation

Table 2: Compositions of Thin film formulations

 

 

 

Method of Film Preparation

Solvent casting method is used to prepare nicotine oral buccal thin films.

 

Step 1:

The optimized Nicotine extract is dissolved in 2ml ethanol; to this ethanol extract PEG 600 (10%), sodium saccharin (3%) and peppermint oil (q.s) were added and then made up the volume as per the petriplate calculation requirement, then filter the solution to get rid of the precipitates.

 

Petri plate calculation

Calculation of API loaded inside the film:                    

Diameter of large Petri dish = 14cm

Radius of the large Petri dish = Diameter/2 = 7cm.

Radius of large Petri plate= πr2

=3.14 X 7 X 7 = 153.86 cm²

Now, drug coated film is cut in to pieces as 2 cm X 2 cm = 4 cm²

4 cm² contain 2 mg drug so, 153.86 cm² contain (?) Drug = 77mg of drug

 

Step 2:

Weighed Polymer was placed in the beaker as per the compositions, and the above formulation mixture was poured in to the beaker sideways such that the polymer powder is completely immersed.

 

Step 3:

Place the beaker containing the formulation mixture in the refrigerator undisturbed to prevent the formation of bubbles. Place the fabricated formulation overnight or until the polymer is completely dissolved.

 

Step 4:

The resultant solution is poured in the Petri plate and dried overnight at room temperature (25^oC -35^OC).

 

Step 5:

The dried film are cut into squares on 2 x 2 cm² films and stored in the aluminium foil for further evaluation.

The same procedure is followed for all the formulations.

 

Evaluation

Physical Appearance

Prepared films were characterized for touch and consistent allocation of the formulation.

 

Weight Uniformity

The weight of each film was checked with the aid of an electronic weighing scale and the mean weight was calculated ^[8].

 

Thickness of Films

Thickness of a film is determined by using calibrated Vernier Calipers and then subsequently mean average is calculated. Generally, three readings from all the batches are determined and average is calculated.

 

Folding Endurance

It is accounted by repeatedly folding a film at the unchanged point until it breaks a apart.  Folding endurance value is number of times the film is folded with no breakage ^[9].

                                                                                                                                                                    

Percentage Elongation

Upon exerting stress on a film, the sample elongates which is referred as strain. Strain is defined as change in length of film divided by its original/initial length of the film specimen. It is determined by the following formula:

 

Disintegration Time

10 ml of distilled water was held in a Petri plate and single film was added on the outside of the water and the point measured until the oral film was softened completely. This test was conducted on randomly selected three films from each lot and average values were calculated ^[8].

 

Surface pH

The 2 cm X 2 cm film was dissolved completely in 2 ml of distilled water. The pH was measured by making the electrode get in touch with the surface of the film and allowing it to equilibrate for 1 minute. The experiments were performed in triplicate and average values were reported.

 

Transparency

Transparency of a slip is evaluated by using a UV-spectrophotometer. This examination is performed for optical appearance of the formulation. Film sample are sliced into rectangular shapes and placed on the inner side of the photometer cell. Transmittance of the film is worked out at 600 nm wavelength.

 

Swelling property

Simulated saliva liquid is used to test the swelling studies of films. Original weight of film is determined and is placed in pre-weighed glass slide. This slide containing film is then dipped into buffer. Increase in the weight of film is noted at constant pre-determined time intervals until no more increase in weight ^[9]. Degree of swelling is calculated by the following parameters:

 

Wt= weight of film at time interval t

W₀ =weight of film at time 0

 

Moisture uptake

Moisture uptake of a film is determined by initial cutting the film with the measurement of 2x2 cm². Later these strips are uncovered to atmosphere with a comparative humidity of 75% at room temperature for 7 days. Moisture uptake is determined as percent weight increase of the strips ^[10].

 

Moisture Loss

It is determined by first finding the initial weight of the film, afterward, putting this film in desiccators for three days. Dessicator possess calcium carbonate. After three days, strips are taken out and weighed again ^[10]. Moisture loss is determined by applying the following formula

 

In-Vitro Drug Release

The in vitro dissolution study is performed through stimulated saliva of pH 6.4 phosphate buffer using USP paddle (Type II) equipment at 37±0.5°C. Samples are withdrawn at predetermined time space and analyzed by UV-Visible spectrophotometer. By this method cumulative drug release and cumulative percentage of drug retained were calculated. The studies were carried out at 37°C with stirring speed of 75 rpm in 900 mL of pH 6.4 phosphate buffer dissolution medium. 5 ml of samples were withdrawn at predetermined time intervals of 5, 10, 15, 20, 30, 40, 50 minutes and replaced with the same volume of buffer. The samples were collected and the absorbance was determined at 256 nm UV-Visible spectrophotometer ^[10].

 

Preparation phosphate buffer of pH 6.4:

13.25 ml of 0.2M dibasic sodium phosphate is mixed with 36.75 mL monobasic sodium phosphate and diluted to 100 mL with Double distilled water to obtain phosphate buffer of pH 6.4.

 

Stability Studies

Accelerated stability studies were conducted by placing the sample at 4^oC and 40^oC for seven days and the following parameters are tested every day.

·      Weight

·      Surface pH

·      Disintegration time

 

RESULTS AND DISCUSSION:

Examination of Nicotine Extract

 

Table 3: Identification test of Nicotine Extract

Identification test	Observation	Nicotine extract
Dragandorff’s test	Reddish brown precipitate	Positive
Hager’s test	Yellow precipitate	Positive
Mayer’s test	Cream precipitate	Positive
Bayer’s test	Reddish brown precipitate	Positive
Picric acid test	Presence of Red crystals	Positive

 

 

Qualitative determination of Nicotine using TLC

The distance travelled by the solute of the standard and the sample was 2cm and 2.1cm respectively. Retention factor was calculated and the values were determined as 3.9 for both standard and sample which indicates the presence of nicotine in the extract in accordance with the standard Nicotine calculations.

 

Quantitative determination of Nicotine content by UV-Vis Spectrophotometer

The absorbance was taken by using UV-Vis Spectrophotometer at 600nm and the absorbance values are mentioned in the graph. The unknown sample’s absorbance was taken as 0.0113 and the unknown sample concentration was calculated in Microsoft excel and the concentration was calculated as 78.08µg/ml. Concentration is taken on X-axis and Absorbance on Y-axis and the standard graph was plotted from which unknown sample’s concentration has been determined. The graphical representation is presented in figure 1.

 

Fig. 1: Quantitative determination of Nicotine

 

Evaluation

Physical Appearance

The prepared films are having visually smooth surface and the drug/polymer distribution was uniform.

 

Fig. 2: Nicotine Thin Films (F1 to F7)

 

Thickness 

Thickness of each film was measured using Vernier Calipers at 6 different locations. The thickness of the films varied between 0.04 + 0.06. According to the obtained results it was observed that increase in polymer concentration increases thickness of the film (table 6).

 

Weight Variation Test

The mass of every the films was found to be consistent. It was originated to be in a range of 0.06 + 0.08 to 0.08 + 0.13 mg. According to the obtained results it was observed that increase in polymer concentration increases weight of the film. Weight variation is an important parameter to consider as any variation in the weight of film leads to under medication or over medication (table 6).

                                                 

Surface pH

The surface pH of all the films exhibited uniformity in their values and were found to be between 6.39±0.09 to 6.99±0.07 representing its compatibility with buccal pH. Hence, no mucosal annoyance was predictable and ultimately achieved patient compliance. Drug content of all the films was established to be uniform which indicates that the drug was distributed uniformly in all the films (table 6).

 

Folding Endurance

Buccal films which shows folding endurance more than 26 times represents good mechanical characteristics. Also, it was observed that increase in thickness of polymer concentration decreases folding endurance value (table 6). 

 

Percentage Moisture Absorption

Percentage moisture absorption (PMA) test was conducted on buccal films of nicotine to determine its physical stability of the film at high humid conditions. Optimum moisture amount in the formulations aids the film to remain stable, non brittle and free from complete drying. Optimum values of moisture absorption in F6 formulation indicate less chance of microbial contamination and maintain integrity through the films shelf life. The obtained values were in a range of 6 to 12.01 % (table 6). 

 

Percentage Moisture Loss

Percentage moisture loss (PML) was conducted on buccal films of nicotine to determine the integrity of the film at dry conditions. The obtained values were in a range of 7.14 to 25 %. F1 shown no loss of weight, and F7 have shown the highest percentage of moisture loss which is 25%, and the films formed with HPMC E5 and HPMC E15 have shown gradual increase of the weight due to decrease polymer concentrations (table 6).

 

Percent elongation

Percent elongation was conducted on mucoadhesion buccal films of nicotine to determine the elongation capacity of the film. The obtained values were in a same range of 111.11%. These results were obtained constant due to the constant concentration of plasticizer (PEG) (table 6).  

 

Swelling index

Swelling index was conducted on mucoadhesion buccal films of nicotine to determine the amount of increased weight of the film. The obtained values were in a same range of 6.42 + 0.04 to 6.58 + 0.06. Increased polymer concentrations have increased the swelling index and this criterion has been proved in all the formulation form F1 to F7 (table 6).

 

Transparency

Transparency was conducted on mucoadhesion buccal films of nicotine under UV at 600nm to determine the percentage transparency of the film. The obtained values were in a same range of 69% to 91%. Formulation mixture was filtered before casting but the transparency of the films reduced due to the dark coloration of nicotine extract (dark black/brown). The values could be improved by crystallization of nicotine extract or by adding opacifying agents (table 6).

 

Disintegration test

The mean disintegration time was 4.98 ± 0.3 minutes. Based on previous experience, we defined a disintegration time of less than 5 minutes to be considered acceptable for this formulation. The disintegration time can be easily adjusted by tuning the composition of the film. F5, F6 and F7 formulations have time reduced for disintegration this is perhaps due to lower concentration of the polymers (table 6).

 

Dissolution

The release profiles of the filmstrips are shown in table 4. F1, F2, F4 drug release was slow and steady but F6, F5 formulations released nicotine rapidly which is 64%, but all the formulation release 99% of the drug in 50 min. The graphical representation of drug release is shown in figure 3.

 

 

 

Table 4: Percentage of drug release of Nicotine Thin Films.

 

 

Fig. 3: Percentage Drug Release of Nicotine Thin Films.

 

 

Stability studies

Accelerated stability studies were conducted by placing the sample at 4^oC and 40^oC for seven days and the weight, surface pH and disintegration parameters are noted on day 1 and day 7. The obtained results are mentioned in the table 5.The results illustrate that weight, surface pH and disintegration time for the formulations at day1 and day 7 of different storage condition did not show much variation, which indicate that accelerated temperature conditions do not alter the properties of the formulations.

 

 

Table 5: Stability studies of buccal films of Nicotine

Stability		Formulation
		Days	F1	F2	F3	F4	F5	F6	F7
400C	Weight	Day 1	0.11	0.16	0.17	0.14	0.16	0.13	0.11
		Day 7	0.10	0.13	0.15	0.13	0.13	0.10	0.10
	pH	Day 1	7.02	6.61	6.89	6.8	6.31	6.12	6.25
		Day 7	6.94	6.58	6.88	6.72	6.11	6.05	6.23
	Disintegration time	Day 1	5.25	6.09	4.01	6.00	5.19	3.38	5.25
		Day 7	5.30	6.58	4.10	6.37	6.44	3.52	5.01
40C	Weight	Day 1	0.11	0.18	0.14	0.08	0.12	0.11	0.10
		Day 7	0.16	0.10	0.12	0.08	0.12	0.11	0.09
	pH	Day 1	7.03	6.56	6.84	6.81	6.35	6.22	6.28
		Day 7	7.01	6.48	6.81	6.77	6.29	6.17	6.19
	Disintegration time	Day 1	5.28	6.10	4.06	6.08	5.15	3.35	5.31
		Day 7	5.34	6.19	4.18	6.23	5.21	3.39	5.38

 

Table 6: Evaluation parameter of Nicotine Thin Films.

Formulation	Thickness	Weight variation (mg)	Surface pH	Foldability	% Moisture Absorption	% Moisture Loss	% Elongation	Transparency  ( %T )	Swelling index (%)	Disintegration (min)
F1	0.058 + 0.01	96.6 + 0.04	7.06 + 0.13	7 +  0.02	9.09 + 0.004	0	111.11	91.99	3.52 + 0.12	5.25
F2	0.098 + 0.02	145 + 0.06	6.65 + 0.16	6 + 0.01	10 + 0.005	8.3 + 0.003	111.11	70.36	3.54 + 0.09	6.09
F3	0.10 + 0.04	60 +  0.04	6.91 + 0.18	12 + 0.04	11.1 + 0.002	7.14 + 0.005	111.11	69.86	3.51 + 0.11	4.01
F4	0.11+ 0.04	73.75 + 0.02	6.83 + 0.15	27 + 0.04	7.14 + 0.002	7.14 + 0.003	111.11	79.98	4.73 + 0.12	6.00
F5	0.05 + 0.01	103.3 + 0.04	6.49 + 0.12	12 + 0.02	12 + 0.004	16.6 + 0.002	111.11	82.37	5.59 + 0.18	5.19
F6	0.08 + 0.02	100 + 0.02	6.21 + 0.16	5 + 0.01	6 + 0.001	20 + 0.006	111.11	84.39	3.26 + 0.08	4.38
F7	0.09 + 0.04	94 +  0.02	6.37 + 0.12	26 + 0.04	10 + 0.002	25 + 0.006	111.11	86.29	2.93 + 0.05	3.25

 

 

CONCLUSION:

Thin films of Nicotine were prepared by solvent casting. The qualitative test revealed the equivalent retention factor values with the standard and test sample and quantitative results eluted that unknown sample concentration was 78.08µg/ml. The films were determined to be consistent, elastic, stabilised at high and low temperatures. Disintegration time was noted to be 5min on an average and surface pH makes it suitable for buccal delivery. Percentage of Transparency was in the range of 69%-90%, later stability studies revealed that the formulations are suitable for varied storage conditions. From the results of percentage drug release, F5 drug released fast (67.08% in 5 min), and the total drug release was obtained in a span of 20min, this formulation can be prepared for fast dissolving thin films and F4 total drug release was obtained in 50 min. Quick release pattern of nicotine through buccal delivery would cause dose dumping and hypotension in case of COPD patients, thus F4 film with the combination of HPMC E15 (5%) and Nicotine (2mg) is considered being the best choice as thin film drug delivery for slow release and would give a steady release of nicotine from thin films. Hence buccal dissolving films of Nicotine were found to be appropriate for eliciting enhanced therapeutic effect in the treatment of COPD and smoking cessation of nicotine.

 

ACKNOWLEDGMENT:

The author is grateful to the administration of Nalla Narasimha Reddy Education Society’s Group of Institutions for providing necessary facilities at the campus for successful completion of the present work also to KP Labs for the gift sample.

 

ABBREVIATIONS:

COPD: Chronic Obstructive Pulmonary Disease, HPMC: Hydroxy Propyl Methyl Cellulose, PEG: Poly Ethylene Glycol, F1 to F7: Formulation, NRT: Nicotine Replacement Therapy, R_f: Retention Factor, TLC: Thin Layer Chromatography, UV-Vis: Ultra Violet Visible, PML: Percentage Moisture Loss, PMG: Percentage Moisture Gain.

 

CONFLICT OF INTEREST:

There is no conflict of interest.

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Accepted on 20.07.2016        © RJPT All right reserved

Research J. Pharm. and Tech 2016; 9(12):2079-2086.