1. INTRODUCTION:
Dimenhydrinate is the Diphenhydramine salt of 8-chlorotheophylline and is chemically recognized as 8-chloro-3,7-dihydro-1,3-dimethyl-1H-purine-2,6-dione in combination with 2- (diphenylmethoxy)-N, N-dimethylethanamine (1:1) (Figure1)1. Dimenhydrinate possesses anti-histaminic, anti-muscarinic and potent sedative effects. It is primarily used as an anti-emetic in the treatment and prevention of motion sickness2.
Figure 1: Dimenhydrinate Structure
The quantification of Dimenhydrinate in various marketed formulations and biological samples were discussed in a number of reports, where analytical methodologies were thoroughly described. These methodologies include HPLC3-5, UV Spectrophotometry6, Liquid Chromatography-Electrospray Tandem Mass Spectrometry6,7 and bio-analytical methods8. Ahmed et al., reported the simultaneous determination of Dimenhydrinate, Cinnarizine, and impurities of Cinnarizine using HPTLC and HPLC chromatographic techniques9. In this report, we present a modified method for estimating Dimenhydrinate in both bulk and tablet formulations using HPTLC, in comparison to a previously reported method10. This new method was developed following the guidelines of the International Conference on Harmonization (ICH)11.
2. MATERIALS AND METHODS:
2.1 Drug and Reagents:
We obtained Dimenhydrinate as a gift sample from Yashica Pharmaceuticals Pvt. Ltd., Thane, India. Dimenhydrinate demonstrated high solubility in ethanol, making it suitable for further method development and validation. All chemicals and reagents used were of analytical grade, and Aluminum-backed Silica gel 60 F254 (10×10cm) pre-coated TLC plates were purchased from E. Merck Chemicals, Mumbai, India.
2.2 Mobile Phase Optimization:
In pursuit of achieving high-resolution and reproducible peaks, we explored various mobile phase compositions tailored to the polarity of Dimenhydrinate. During optimization, we encountered several challenges, including band spreading, tailing, and low Rf values. Ultimately, we settled on a Benzene: Methanol mixture (8:2 v/v) as the mobile phase, which yielded an Rf value of 0.47±0.02 and resolved the aforementioned issues. For maximum sensitivity, we determined that a wavelength of 279nm was optimal.
2.3 Instrumentation:
We utilized a High-Performance Thin-Layer Chromatography (HPTLC) system from CAMAG (Muttenz, Switzerland), which consisted of Camag's Linomat 5 applicator connected to a nitrogen cylinder, a Hamilton syringe (100µL), Camag's TLC Scanner 3, Camag Wincats software (Version 1.4.10), Camag twin trough chambers (10×10cm and 20×10cm), and an ultrasonicator from ENERTECH Electronics Pvt. Ltd.
For sample application and calibration standards, we used a 100µL Hamilton syringe and Linomat 5 sample applicator to create bands 6mm wide and spaced 6mm apart. The chromatography was performed on a 10 x 10 cm silica gel 60 F254 plate (E. Merk, Mumbai, India) with a thickness of 200µm. Before use, the plates were washed with methanol and activated in an oven at 110°C for 5 minutes.
An Automatic Developing Chamber (ADC 2) was employed for plate development using a mobile phase composed of Benzene: Methanol (8:2, v/v) with a saturation time of 25minutes at 25±1°C and relative humidity controlled at 35±5%. In the ADC2 chamber, the development distance and time were set at 80 mm/sec and 15minutes, respectively. The slit dimensions were maintained at 6.0×0.45mm, and the scanning speed was set at 20mm/s-1. We conducted scanning using the densitometric TLC Scanner 3 in absorbance-reflectance mode at 279nm after an initial scan between 190-800nm using deuterium lamps.
2.4 Preparation of Stock Standard Solution:
We transferred the 10mg weighed Dimenhydrinate into 10mL of volumetric flask and made up the volume up to mark with absolute grade ethanol to obtain the concentration 1000µg/mL of Dimenhydrinate. From the standard stock solution of Dimenhydrinate, an appropriate volume ranging from 0.5µL to 3.0µL was over spotted on TLC plates.
2.5 Analysis of Tablet Formulation:
The average content of ten Draminate tablets (each containing 50mg of Dimenhydrinate) was determined by weighing their contents. The tablets were ground to a fine powder in a mortar, and an amount equivalent to 50 mg of Dimenhydrinate was transferred to a volumetric flask. It was then dissolved and diluted with absolute-grade ethanol and sonicated for 15 minutes. A Whatman filter paper with a mesh size of 0.45µm was used to filter the resulting solution. The filtrate was subsequently transferred to a 100mL volumetric flask. From this solution, six replicates with a concentration of 2000 ng/band were applied to the plate.
2.6 Method Validation:
According to the Q2R1 guidelines of the International Conference on Harmonization, the proposed analytical method was validated for linearity, precision, accuracy, ruggedness, etc.11,12-21
2.7 Linearity and Calibration Curve:
The stock standard solutions of 1000µg/mL of Dimenhydrinate was used for the linearity study and volume of 0.5-3.0µL was spotted on HPTLC plates to obtain 500, 1000, 1500, 2000, 2500 and 3000ng/band of Dimenhydrinate, respectively (Figure 2). The calibration curve of concentration vs area was determined in the range between 500-3000ng/band.
Figure 2: Standard Dimenhydrinate chromatogram of NP-HPTLC
2.8 Precision:
The developed method was validated for repeatability, intraday and inter-day precision using the three different concentrations of the Dimenhydrinate. For each concentration, the measurements were repeated six times for repeatability. Intraday precision was calculated by performing the same method three times on the same day for three different Dimenhydrinate concentrations of 1000, 1500, and 2000ng/spot, respectively. The interday precision of the method was determined by performing a similar method on different days under the same experimental conditions. Repeatability was performed using the same concentration 2000ng/spot on plate. It was calculated in terms of % RSD for the analytes with experimental condition.
2.9 LOD and LOQ:
The limit of detection and limit of quantitation of Dimenhydrinate was obtained by investigating the signal-to-noise ratio as per the ICH guideline. For the sensitivity study, different volume of standard stock solution in the range 500-1000ng/spot of Dimenhydrinate were prepared. The LOD and LOQ were calculated by LOD = 3.3 × N/B and LOQ = 10 × N/B, where N and B denotes the average standard deviation of peak area of the drugs and slopes of the calibration curve.
2.10 Accuracy:
Accuracy study was carried out by recovery analysis, where a known amount of standard solution was over spotted at three different stages i.e. 80%, 100%, and 120%.
% Recovery = Amount found – Initial amount/Amount Added × 100
2.11 Ruggedness:
When two independent analysts carried out the analysis under the same experimental and environmental conditions, the methods should be rugged. Hence, at a concentration of 2000ng/spot, the HPTLC method was evaluated for ruggedness.
3. RESULTS:
This is the first report where, we are reporting the estimation of Dimenhydrinate in bulk and tablet formulation by HPTLC. The Benzene: Methanol (8:2 v/v) mobile phase was finalized with Rf value 0.47±0.02 for the validation of the Dimenhydrinate. For the highest sensitivity, 279nm wavelength was found to be optimal as shown in Figure 2.
The developed method was found to be linear in the concentration range of 500-3000ng/band with regression coefficient of (R2) = 0.999 as shown in Figure 3 and Figure 4. The results of the linearity study are depicted in Table 1.
Table 1. Result from Linearity
|
Parameters |
NP-HPTLC |
|
Linear range (ng/spot) |
500-3000 ng/spot |
|
Slope |
6.098 |
|
Intercept |
11.12 |
|
Correlation coefficient |
0.9991 |
To evaluate the applicability of the developed method for the estimation of the Dimenhydrinate in marketed pharmaceutical formulation, we have performed the tablet assay. The percentage amount found in the Dimenhydrinate tablet formulation was 99.68% with RSD of 1.36 % (Table 2).
Figure 3: 3D linearity of NP-HPTLC
100%, and 120% was established. The percent recovery of the method was observed in the range 99.43-101.41 %, indicating its accuracy (Table 3).
Table 2. Analysis of tablet formulation (n=6)
|
Drug |
Amount found (%) |
RSD (%) |
|
Dimenhydrinate |
99.68 |
1.36 |
The percent recovery of Dimenhydrinate was performed at the three concentration levels of 80%
Three replicates in three different concentrations of Dimenhydrinate (1000, 1500, and 2000ng/spot) have been used to evaluate intra-day and inter-day precision and 2000ng/spot for reparability for six replicates. It shows that the %RSD did not surpass 2%, indicating that the method was precise for Dimenhydrinate (Tables 4).
Table 3. Results of Accuracy (n=3)
|
Initial amount of drug (ng/spot) |
Amount of standard drug added (%) |
% Recovery |
% RSD |
|
800 (ng/spot) |
80 |
99.43 |
1.34 |
|
100 |
101.41 |
1.05 |
|
|
120 |
100.90 |
1.63 |
AUC
Concentration µgm L-1
Figure 4: Calibration curve of Dimenhydrinate
Table 4. Results of Precision
|
Parameter |
Concentration (ng/spot) |
Amount found (ng/spot) |
RSD (%) |
|
Intra-day (n=3) |
1000 |
993.83 |
0.40 |
|
1500 |
1493.90 |
0.42 |
|
|
2000 |
1992.70 |
0.58 |
|
|
Inter-day (n=3) |
1000 |
984.99 |
0.42 |
|
1500 |
1494.80 |
0.40 |
|
|
2000 |
1992.00 |
0.58 |
|
|
Repeatability (n=6) |
2000 |
1993.48 |
1.15 |
The developed method was sensitive with detection limit of 5.9824ng/band and quantification limit of 18.128 ng/band. Two different analysts evaluated the ruggedness of HPTLC methods, with a RSD less than 2% suggesting that a method was rugged (Table 5).
Table 5. Results from ruggedness
|
|
Concentration (ng/spot) |
Amount found (ng/spot) |
% RSD (n=6) |
|
Analyst I |
2000 |
1992.7 |
0.57 |
|
Analyst II |
2000 |
1994 |
0.95 |
4. CONCLUSION:
Dimenhydrinate has anti-histaminic, anti-muscarinic and compelling sedation effects. In the current study a new, simple, sensitive and rugged HPTLC method for determining Dimenhydrinate in bulk and pharmaceutical dosage form was developed and successfully validated. With respect to the ICH guideline, the developed method was validated by performing the parameters such as accuracy, precision, sensitivity and ruggedness. The obtained results of proposed HPTLC method were within acceptable limit and could be useful for the daily routine analysis for the determination of the Dimenhydrinate in bulk and tablet matrix.
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Received on 10.01.2026 Revised on 20.02.2026 Accepted on 25.03.2026 Published on 16.04.2026 Available online from April 18, 2026 Asian Journal of Pharmaceutical Analysis. 2026; 16(2):105-108. DOI: 10.52711/2231-5675.2026.00015 ©Asian Pharma Press All Right Reserved
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