Ambikar R. B.* 1 ; Deokar G. S.
2
1.
Padmashree Dr. D. Y. Patil College of Pharmacy, Akurdi, Pune-411044, India.
2.
Department of Pharmaceutics, Bhujbal Knowledge City, Institute of Pharmacy,
Nashik, India rajashriwin@gmail.com
“Author of correspondence”
Ambikar R. B.,
Padmashree Dr. D. Y. Patil College of Pharmacy,
Akurdi, Pune-411044, India.
1

Benzydamine hydrochloride (BEN) has immediate action on vaginal inflammation, also has an activity against Trichomonas vaginalis and Gardnerella vaginalis.
Of vaginal dosage forms, patients are known to better tolerate gels. However, the direct application of gels onto the infected sites of the vagina might be difficult, inconvenient as well as need frequent dosing. Rapidly dispersible gel forming tablets (RDVT) offers convenience of dosing methods of tablet and disintegrates rapidly to form bioadhesive gel. Croscarmellose used as superdisintegrant, and Hydroxypropylmethylcellulose (F1,
F2) and Carboxymethylcellulose sodium (F3, F4) as gelling polymer. Formulations F3 and F4 showed longer disintegration time; hence these formulations were not further evaluated. Formulation F1 showed 95% benzydamine release, whereas F2 showed 99% release within 10 minutes. The gel has an acidic pH. Gel formed immediately after complete dispersion of tablet showed good viscosity and sufficient in vitro force of adhesion.
Benzydamine, vaginitis, rapidly dispersible, vaginal tablets
Vaginal route of drug administration is commonly used for the local therapy of specific gynaecological diseases. Delivery via the vagina has some additional advantages over oral delivery: the avoidance of hepatic first-pass metabolism, a reduction in the incidence and severity of gastrointestinal and/or hepatic side effects.
1
Considerable progress has been made over the last ten years in investigating and developing novel vaginal drug delivery systems with desirable distribution, bioadhesion, retention and release characteristics. Attempts are being made to develop novel vaginal drug delivery systems that can meet the clinical as well as the patient’s requirements.
2, 3,4
Vaginitis is one of the most frequent gynaecological diseases. Vaginitis is an inflammation of the vagina. It can result in discharge, itching and pain, and is often associated with an irritation or infection of the vulva. Common infectious forms of vaginitis include bacterial vaginosis, vulvovaginal candidiasis, and trichomoniasis.
7
Vaginitis by Trichomonas vaginalis is the most common sexually transmitted infection, but vaginitis can be also the result of candidiasis and infection by mixed bacterial flora.
8
Benzydamine hydrochloride is a nonsteroid anti-inflammatory drug (NSAID), has immediate action on vaginal inflammation.
9
Benzydamine also found display an activity against Trichomonas vaginalis and Gardnerella vaginalis at concentrations in the region of 10-20 μg/ml, while its activity against fungi and the other bacteria manifests itself only at concentrations that are 10-20 times as great.
10, 12
Marketed vaginal preparations of benzydamine hydrochloride are vaginal douche
(0.1% w/v aqueous solution) and vaginal cream (0.5% w/w). These dosage forms suffer from disadvantages like these vaginal preparations are messy to apply, can leak in the undergarments and give an uncomfortable feeling to the user. Moreover, semi-solid formulations may not allow accurate drug dosing due to non-uniform distribution in and leakage from the vaginal cavity.
13
Of vaginal dosage forms, patients are known to better tolerate gels than inserts or ointments. The direct application of gels onto the infected sites of the vagina might be difficult as well as inconvenient. Moreover, conventional gels often require a frequent
2

dosing regimen owing to the self-cleansing action of the vagina, namely the secretion of mucus and humid site of administration.
14
Convenience of dosing methods is an important factor in the design of vaginal application forms. Although vaginal tablets are easy to apply by the user and provide accurate drug dosing, but vaginal disintegration of conventional tablets can be slow and due to gravity the tablets are rapidly cleared from the vagina.
15
This can be reduced using rapidly dispersible vaginal tablets which disintegrate rapidly forming a stable, smooth, bioadhesive, water-miscible, anti-infective gel on placing it in approximately 2 ml fluid.
16
Rapidly Dispersible gel forming tablets offers advantages of tablet and overcome drawbacks of gel.
MATERIALS
Benzydamine was gifted by Elder pharmaceuticals ltd., Navi Mumbai, India.
Hydroxypropylmethylcellulose (HPMC, Loba Chemie, Mumbai),
Carboxymethylcellulose sodium (CMC, Loba Chemie, Mumbai), Croscarmellose sodium (FMC Europe N.V.) were used. All other chemicals were of pharmacopoeial grade. Double distilled water was used whenever required
PREPARATION OF BENZYDAMINE RAPIDLY DISPERSIBLE VAGINAL
TABLETS
The tablets were prepared by the Method of Stone et al.
16 The powder ingredients are thoroughly mixed in a beaker by hand, then the glycerol was added and thoroughly mixed in, again by hand. Various ingredients and quantities used were as shown in the
Table 1.
The compression of powder blend was done by direct compression method.
The compression was carried out using 11.2 mm flat-faced circular punches on rotary compression machine (General Machinary Co., Mumbai.). Tablets were prepared by varying the concentration of croscarmellose sodium i.e. 6 %w/w and 12 %w/w.
Table No. 1: Compositions of benzydamine rapidly dispersible vaginal tablets
Ingredients Quantity in mg
F1 F2 F3 F4
Benzydamine
HPMC
CMC
Glycerol
Croscarmellose sodium
Microcrystalline cellulose
Mannitol
10
100
-
70
33
100
237
10
100
-
70
66
100
204
10
-
100
70
33
100
237
10
-
100
70
66
100
204
EVALUATION OF BENZYDAMINE RAPIDLY DISPERSIBLE VAGINAL
TABLETS
3

1.
Thickness
The thickness of the tablets was determined using a vernier caliper. Five tablets from each batch were used, and an average value was calculated.
2.
Weight variation
Weighed accurately 5 tablets and average weight was calculated.
3.
Hardness
For each formulation, the hardness of five tablets was checked using the Monsanto hardness tester.
4.
Friability
For each formulation, twenty tablets were selected randomly and weighed. Tablets were then placed in friability testing apparatus i.e. Roche Friabilator (Remi Electronics,
Mumbai, India), which was rotated at a speed of 25 rpm for 4 minutes. Tablets were then weighed and friability values were determined.
5.
Disintegration time
The disintegration time of tablets were measured in 10 ml distilled water (37
0
C). The disintegration time was determined thrice.
6.
Drug content
Five tablets were powdered and the blend equivalent to 10 mg of benzydamine hydrochloride was weighed and dissolved in 100 ml of 0.1N hydrochloric acid.
Solution was filtered and diluted and drug content analyzed spectrophotometrically at
306 nm.
7.
In-vitro bioadhesion study 20
Tablet was dispersed in 2 ml simulated vaginal fluid. The resulting gel was subjected to bioadhesive study.
In the present study, rat peritoneum membrane was used as a model surface for bioadhesion testing. Excised and trimmed evenly from the sides. It was then washed in phosphate buffer (pH 4) and was preserved in same or used immediately.
The two sides of the balance were balanced with 5 g weight on right hand side. The rat peritoneum was excised and washed and tied tightly with the mucosal side upward using a thread over the protrusion in the rubber block which is covered with aluminium surface. The block was then lowered into the glass container, which was then filled with isotonic phosphate buffer (pH 4) kept at 37
0 ±1 0
C, such that the buffer just reaches the surface of mucosal membrane and keeps it moist. This was then kept below the left hand set up of the balance. The gel was applied at the border adhered to a aluminium surface hanging on left hand side and the beam raised, with the 5 g weight removed on the right pan side. This lowered the aluminium surface along with the gel over the mucosa, with a weight of 5 g. The balance was kept in the position for 8 min. and then slowly water was added to the plastic container in the right pan by pipette. The addition of water was stopped as soon as the detachment of two surfaces was obtained. Weight of water was measured. The excess weight in the pan i.e. total weight minus 5 g is the force required to separate gel from the mucosa.
This gave bioadhesive strength. Force of Adhesion (dyne/cm
2
) is calculated as follows,
Force of Adhesion =
W × 980
A
Where, W = Excess weight in pan, and
A = Area of the peritoneum membrane.
8.
Effect on pH value of medium
4

The effect of benzydamine hydrochloride effervescent vaginal tablets on pH value of phosphate buffer (pH 4.0) was investigated. The tablet was placed within 40 ml of medium, and the pH values of medium were measured using digital pH meter
(LOSHCON, CL 54+) and recorded when complete tablet get disintegrated.
9.
In-vitro Benzydamine release study
Release studies were carried out using the USP 29 dissolution apparatus II paddle type
(LABINDIA DISSO, Digital tablet dissolution test apparatus), in 900 ml phosphate buffer solution pH 4.0 (PBS) as the dissolution medium. The rate of stirring was 70 rpm. And the medium temperature was maintained at 37±0.5
0
C. At each sampling interval, 5 ml of the dissolution medium was withdrawn and replaced by an equal volume of fresh PBS. Benzydamine was determined at 304 nm by using a UV-2450 spectrophotometer (SHIMADZU).
10.
Viscosity measurement
Tablet was added to 2 ml of simulated vaginal fluid. The viscosity of formulation was determined by brookfield viscometer (DV-II + PRO) using spindle No.62, at rpm 10.
11.
Physicochemical interaction studies a) Differential Scanning Calorimetry (DSC)
DSC analysis was performed using Thermal Analyzer DSC60 (SHIMADZU) by taking
2 to 5 mg samples. Sample were hermetically sealed aluminium pan and heated at a rate of 10°C/min conducted over a temperature range of 30 to 300°C under nitrogen with flow rate of 10°C/min. Before the analysis all samples were vacuum dried for 24 hours. b) Fourier Transform Infrared Spectroscopy (FTIR) Interpretation
The infrared spectra of pure benzydamine samples were recorded by FTIR spectrometer 84005 (SHIMADZU), equipped with Inferometer detector. Samples were prepared by KBr disc method (2 mg sample in 100 mg KBr) and examined in the transmission mode. Each spectrum was measured over a frequency range of 4000–400 cm
−1
.
The software used for the data analysis was Perkin-Elmer Spectrum 3.02. The peaks obtained in the spectra were then compared with corresponding functional groups in the structures of benzydamine.
12.
Stability Study
Each batch of 5 tablets was wrapped in aluminium foil and stored at 40

2 0 C temperature with relative humidity of 75

5%. The sampling was done after three month and evaluation was done for appearance, thickness, hardness, friability and drug content.
EVALUATION OF BENZYDAMINE RAPIDLY DISPERSIBLE VAGINAL
TABLETS
The parameters studied for evaluation of benzydamine rapidly dispersible vaginal tablets were given in Table 2.
Table No. 2: Evaluation parameters of benzydamine rapidly dispersible vaginal tablets
Formulation code F1 F2 F3 F4
Thickness (mm) 5.068±0.0228 5.128±0.07823 5.288±0.0228 5.252±0.0228
Average weight (mg) 552.5±2.665 554.33±2.422 553.66±3.327 554.66±1.966
5

Hardness (kg/cm 2 ) 2.68±0.228 2.6±0.1414 2.76±0.1673 2.68±0.1095
Friability (%)
Disintegration time (min.)
Drug content (%)
0.647
11.58±1.275
98.23±3.24
0.678
8.49±1.376
99.23±2.68
0.654
>20
-
0.668
>20
-
Force of adhesion (dyne/cm 2 )
479.34
Effect on pH of phosphate buffer pH 4 4.78
Values are expressed as mean ± S.D.
445.87
4.81 -
-
-
-
The diameter of tablet observed was 11.2 mm. Average weight of the tablets were found between 552.5 mg to 554.66 mg. Tablet weight was kept maximum to avoid its clearance from vaginal tract. Hardness was found between 2.6 kg/cm
2 and 2.76 kg/cm
2
.
The friability ranged between 0.678% and 0.647%. Thus, all the physical parameters of the tablets were practically within control. Drug content (%) of F1 and F2 was found under limit.
Disintegration time for F1 and F2 was found to be approximately 11 minutes and 8 minutes respectively. For Formulations F3 and F4 containing CMC disintegration time was found to be >20 minutes. These two formulations showed longer disintegration time; hence these formulations were not further evaluated.
Both formulations F1 and F2 showed nearly comparable force of adhesion. The force of adhesion of resulting gels was sufficient to hold gel on mucus membrane.
The effect of tablets on pH of vaginal tract was determined in vitro using phosphate buffer pH 4. Formulation F1 and F2 showed pH change within normal pH range of vaginal fluid (3.2- 4.8).
The mannitol powder contributes to the tablet's physical stability and acts as a "wicking agent," readily absorbing water and transporting it to the tablet's interior. Glycerol provides the hyperosmolarity needed to withdraw fluid (transudate) through the vaginal epithelium into the vaginal lumen to assist in the tablet's disintegration.
Formulation F1 containing 6% w/w croscarmellose sodium shown optimum disintegration time, hence formulation F1 was selected for rheological studies, physicochemical interaction studies (Differential scanning calorimetry and FTIR
Spectrum) and stability studies.
IN-VITRO BENZYDAMINE RELEASE STUDY
The percent cumulative release was shown for F1 and F2 formulations in Fig. 1.
Formulation F1 showed 95% benzydamine release, whereas F2 showed 99% release within 10 minutes. Formulation F1 containing 6% w/w croscarmellose showed lower benzydamine release than F2, whereas F2 containing 12% w/w showed nearly complete release within 10 minutes. Formulation F1 considered as optimized as it showed desirable disintegration time and desirable % drug release with minimum concentration of croscarmellose.
6

100
80
60
40
F1
F2
20
0
0 2 4 6 8 10
Time (min.)
Figure 1. % Drug release of benzydamine rapidly dispersible vaginal tablet
VISCOSITY MEASUREMENTS
Viscosity (cP) of benzydamine rapidly dispersible vaginal tablet (F1) in 2 ml of simulated vaginal fluid determined by Brookfield viscometer using spindle No. 62, at rpm 10 for 5 hours. Tablet showed good viscosity immediately after complete dispersion. There was considerable increase in viscosity with time (Fig. 2); so even after dilution with vaginal fluid in vaginal tract, viscosity will be sufficient to retain the formulation in vaginal tract. % Torque also increased with time.
The hydroxypropylmethylcellulose (HPMC) serves as a rapidly soluble gelling agent to ensure that the resulting gel has the necessary viscosity, rheological and bioadhesive properties. The inert microcrystalline cellulose serves to form a thixotropic gel which helps to provide an effective suspension. The inert microcrystalline cellulose has fine particles (i.e., not "gritty"), so as not to cause discomfort either to the female user of the tablet or to her male partner.
50
45
40
35
30
25
20
15
10
5
0 2 4 6
Viscisity (cP)
% Torque
Time (hours)
Figure 2. Viscosity (cP) and % Torque of benzydamine rapidly dispersible vaginal tablet (F1) in simulated vaginal fluid.
PHYSICOCHEMICAL INTERACTION STUDIES
These studies are carried out on formulation F1. a) Differential scanning calorimetry (DSC)
7

Thermal analysis of drugs alone as well as that of the optimized formulation of benzydamine rapidly dispersible vaginal tablet (F1) was carried out using DSC (Fig. 3).
The DSC curve of benzydamine profiles a sharp endothermic peak at 162.25°C.
Overlay Spectra of benzydamine and RDVT-F1 showed shifting of drug peak from
162.25 0 C to 158.27
0 C. There was not considerable shifting of the peak indicating that there may be physical reaction with excipient present in tablet, but no any chemical reaction.
DSC mW
0.00
Sample Name: BNZ Pure
-10.00
Peak
Onset
Endset
Heat
Peak
Onset
Endset
Heat
Sample Name: RDVT
-20.00
100.00
200.00
Temp [C]
300.00
Figure 3. Overlay spectra of benzydamine and benzydamine rapidly dispersible vaginal tablet
(F1) b) FTIR Spectrum of Benzydamine rapidly dispersible vaginal tablet
The interaction between the drug and the excipient often leads to identifiable changes in the FTIR profile of formulation. To check for any interactions occurring in optimized formulations, their FTIR spectra were recorded (Fig. 4).
Slight difference was seen in the position of the absorption bands of Benzydamine occurred in spectra of benzydamine rapidly dispersible vaginal tablet (F1). However, the major characteristic peaks for benzydamine were still present indicating that there was no any chemical interaction between drug and excipients. Important vibrations detected in the spectrum of benzydamine rapidly dispersible vaginal tablet (F1) are shown in Table 3.
8

60
%T
52.5
45
37.5
30
22.5
15
7.5
0
-7.5
4000
RDVT
3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600
Figure 4. FTIR spectrum of benzydamine rapidly dispersible vaginal tablet (F1)
Table No. 3: Identified functional groups present in benzydamine rapidly dispersible vaginal tablet
1/cm
400
(F1)
Principle Peak Observed values (cm -1 ) Spectrum of Benzydamine (group)
785.05
1014.59
1161.19
Appearance
CH
3 rocking
C–N bending
C–O stretching in ether
2359.02 C–N stretching
STABILITY STUDY
Stability studies were conducted only for formulation RDVT (F1).
Table No. 4: Evaluation of formulation benzydamine rapidly dispersible vaginal tablet (F1) kept for stability at 40 0 C /75%RH
Parameter After 3 months
White colour
Thickness (mm)
Hardness (Kg/cm 2 )
5.08
2.3
Drug content (%) 98.78
The short term stability study of selected formulation (RDVT-F1) was performed as per
ICH (International conference on harmonisation) guidelines at temperature 40° C and
75% RH for three month. The results of stability study (Table 4) revealed that drug content and all other parameters were within the acceptable limit.
9

In this study rapidly dispersible tablets were successfully prepared using croscarmellose sodium as superdisintegrant and HPMC. With CMC desirable disintegration time was not obtained. Formulation F1 containing HPMC, with 6% w/w superdisintegrant had shown optimum disintegration time (approx. 10 min.). Gel formed after complete dispersion of formulation F1 in simulated vaginal fluid showed sufficient force of adhesion to hold gel on mucosal membrane. Rheological studies of
F1 showed increased viscosity with time. DSC and FTIR data reviles that there was no significant interaction between drug and excipient. Formulated tablets will disintegrate rapidly in vaginal tract and immediately will form bioadhesive gel.
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