Method Development and Validation of Zolmitriptan in Tablet Dosage Form by HPLC and IR Spectroscopy

Abstract

The present work aims to develop and validate an analytical method for the quantitative determination of Zolmitriptan in tablet dosage form using Reverse Phase High-Performance Liquid Chromatography (RP-HPLC) and Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) Spectroscopy. Zolmitriptan, a selective 5-HT1B/1D receptor agonist, is widely used in the acute treatment of migraine. The RP-HPLC method was developed using a C18 column with a mobile phase of acetonitrile and 0.1% orthophosphoric acid (60:40 v/v) at a flow rate of 1.0 mL/min, with UV detection at 225 nm. The retention time was observed at approximately 5.2 minutes. The ATR-FTIR method was employed for identity confirmation by characterizing the functional groups and establishing a spectral fingerprint of the drug. Method validation was carried out as per ICH Q2(R1) guidelines covering specificity, linearity, accuracy, precision, LOD, LOQ, and robustness. The method demonstrated excellent linearity in the range of 10–50 µg/mL (r² = 0.9999), percentage recovery of 99.12%–101.35%, and %RSD ? 0.85% for all precision studies. The validated methods are suitable for routine quality control of Zolmitriptan in tablet formulations.

Keywords

Zolmitriptan, RP-HPLC, ATR-FTIR Spectroscopy, Method Validation, ICH Q2(R1), Tablet Dosage Form, Migraine, Quality Control.

Introduction

Migraine is a debilitating neurological disorder affecting approximately 15% of the global population, manifesting as recurrent episodes of severe, often unilateral pulsating headache accompanied by nausea, vomiting, and photophobia. The social and economic burden imposed by migraine is substantial, classifying it among the leading causes of disability worldwide.

Zolmitriptan (molecular formula: C16H21N3O2; molecular weight: 287.36 g/mol) is a second-generation triptan that acts as a selective agonist at 5-HT1B and 5-HT1D receptors. This mechanism leads to the constriction of dilated intracranial blood vessels and inhibition of vasoactive neuropeptide release from trigeminal nerve endings, effectively aborting the migraine attack.

Zolmitriptan is available commercially as 2.5 mg and 5 mg tablets, orally disintegrating tablets, and nasal sprays under the brand name Zomig®. Despite its widespread clinical use, robust and validated analytical methods for its quantitative determination in tablet dosage forms remain essential for pharmaceutical quality assurance.

High-Performance Liquid Chromatography (HPLC) and Infrared (IR) Spectroscopy are among the most powerful analytical tools in pharmaceutical analysis. RP-HPLC offers high sensitivity, selectivity, and precision for quantitative analysis, while FTIR spectroscopy provides rapid, non-destructive qualitative identification based on functional group fingerprinting. The goal of this work is to develop and validate these methods for the finished product tablet formulation of zolmitriptan.

DRUG PROFILE OF ZOLMITRIPTAN:

Chemical and Physical Properties:

Zolmitriptan is a white to pale-yellow crystalline powder with molecular formula C16H21N3O2 and molecular weight 287.36 g/mol. It has a pKa of approximately 9.64, water solubility of ~7.5 mg/mL at 25°C, and log P ≈ 0.74. The UV absorption maximum (λmax) in methanol is observed at 225 nm. The compound contains an indole nucleus with a dimethylaminoethyl side chain and an oxazolidinone moiety responsible for its pharmacological activity.

Pharmacological Profile:

Zolmitriptan acts selectively on 5-HT1B and 5-HT1D receptors, causing vasoconstriction of intracranial vessels and inhibiting release of CGRP and Substance P. Following oral administration, bioavailability is ~40–48%. It is metabolized by MAO-A to an active N-desmethyl metabolite with a terminal half-life of approximately 3 hours.

Marketed Formulations:

Zolmitriptan is commercially available as 2.5 mg and 5 mg immediate-release tablets, 2.5 mg orally disintegrating tablets, and 2.5 mg/0.1 mL nasal sprays. The drug is listed in the British Pharmacopoeia (BP) and is subject to stringent quality control requirements.

HPLC METHOD DEVELOPMENT:

1. Sample Preparation:

Sample preparation depends on the formulation type:

a) Tablet (Direct Dissolution — Preferred):

1. Weigh tablet powder equivalent to 10 mg of zolmitriptan into a 100 mL volumetric flask.

2. Add diluent (methanol:water, 50:50), sonicate for 15 minutes, filter through 0.45 µm PVDF membrane, and dilute to mark.

b) Standard Solution Preparation:

Accurately weigh 10 mg of zolmitriptan reference standard (purity ≥ 99.5%), dissolve in methanol, and dilute to 100 mL with diluent to obtain 100 µg/mL stock. Further dilute to working standards of 10–50 µg/mL.

2. Instrument Parameters:

Table 1: Optimized Chromatographic Conditions

Parameter	Specification
Column	C18 (150 mm × 4.6 mm, 5 µm)
Mobile Phase	Acetonitrile : 0.1% Orthophosphoric acid (60:40 v/v)
Flow Rate	1.0 mL/min
Detection Wavelength	225 nm
Injection Volume	20 µL
Column Temperature	25°C ± 2°C
Run Time	10 minutes
Retention Time	~5.2 minutes
Diluent	Methanol : Water (50:50 v/v)

Method and Procedure:

? Step 1: Selection of Analytical Wavelength

•  Record UV absorption spectrum of zolmitriptan (200–400 nm); λmax observed at 225 nm.

•  225 nm selected for optimal sensitivity and selectivity.

? Step 2: Mobile Phase Optimization

•  Trials conducted with various combinations of acetonitrile/methanol and phosphate buffer/orthophosphoric acid at different ratios.

•  Acetonitrile:0.1% orthophosphoric acid (60:40 v/v) selected — well-resolved symmetrical peak, acceptable tailing factor, 10 min run time.

? Step 3: Column and Flow Rate Selection

•  C18 column (150 mm × 4.6 mm, 5 µm) selected for reversed-phase behavior.

•  Flow rate optimized at 1.0 mL/min; retention time ~5.2 min with good peak shape.

? Step 4: System Suitability Testing

•  Six replicate injections of 30 µg/mL standard solution performed before sample analysis.

•  Theoretical plates: 6842; tailing factor: 1.05; %RSD of peak area and RT within ±2.0%.

? Step 5: Create Reference Calibration Curve

•  Prepare calibration standards at 10, 20, 30, 40, and 50 µg/mL in triplicate.

•  Plot mean peak area vs. concentration; regression equation: Peak Area = 28,453 × Concentration + 1,250; r² = 0.9999.

•  Develop a chromatographic library of approved batches for batch-to-batch comparison.

ATR-FTIR METHOD DEVELOPMENT:

1. Instrument Performance Verification:

Ensure the FTIR instrument and ATR accessory are calibrated. Wavenumber accuracy and spectral resolution are verified using a NIST-traceable polystyrene film standard. Allow the system to pass all performance tests before analysis.

2. ATR Crystal Preparation and Background Measurement:

Clean the ATR crystal (diamond or ZnSe) with alcohol or acetone using a lint-free wipe. Record a background spectrum with a clean empty crystal to subtract atmospheric interferences (water vapor and CO?) from sample spectra.

3. Sample Application:

Place a small amount (~10 mg) of the tablet powder directly onto the center of the ATR crystal. Ensure sufficient and consistent contact with the crystal surface using an anvil with appropriate pressure. Consistent pressure is crucial for reproducible results.

4. Spectra Acquisition:

Optimize instrumental parameters: number of scans (32–64), resolution (4 cm?¹), and spectral range (4000–400 cm?¹). Acquire the sample spectrum in absorbance mode.

5. Qualitative Analysis and Data Processing:

Identify characteristic peaks for zolmitriptan and excipients to confirm chemical identity and check for interactions. Apply baseline correction, smoothing, and normalization to enhance spectral quality.

Table 2: Characteristic IR Absorption Bands of Zolmitriptan

Functional Group	Expected (cm?¹)	Observed (cm?¹)
N–H Stretch (2° amine)	3200–3400	3325
O–H Stretch (hydroxyl)	2500–3300	2920
C=O Stretch (oxazolidinone)	1630–1680	1659
C–N Stretch	1000–1250	1172
C–H Aromatic	3000–3100	3055
C–H Aliphatic	2850–2960	2930
N–H Bend	1500–1600	1558
C=C Aromatic	1450–1600	1490

6. Analysis of Formulation:

1. Obtain FTIR spectra of pure reference standards of active ingredients; note key functional group peaks (–OH, C=O, aromatic C=C).

2. Record FTIR spectra of the finished tablet formulation.

3. Compare sample spectrum with reference spectra; confirm presence of zolmitriptan by matching characteristic peaks.

7. Check for Interactions:

Look for shifts, disappearance, or broadening of peaks that may indicate interactions between active and tablet excipients. For example:

A) Hydrogen bonding may shift –OH peaks.

B) Esterification or oxidation may alter carbonyl peaks.

C) Broadening of N–H bands may indicate interaction with binders or fillers.

8. Quantitative Analysis (if applicable):

Prepare a calibration curve using standard concentrations of zolmitriptan. Measure the absorbance at the characteristic C=O stretching peak (1659 cm?¹) and plot against concentration (Beer-Lambert law). Chemometric methods such as PLS or PCR may be used for complex formulations where spectral overlap occurs.

VALIDATION PARAMETERS (AS PER ICH Q2(R1)):

Table 3: Validation Parameters — HPLC and FTIR Approach

Parameter	HPLC Approach	IR / FTIR Approach
Specificity	No interfering peaks at RT ~5.2 min	Active peaks distinct from excipient peaks
Precision	6 replicate injections; %RSD ≤ 0.85%	Same sample repeated; peak positions compared
Accuracy	Standard addition; recovery 98–102%	Peak area ratios vs. reference standard
Linearity	10–50 µg/mL; r² = 0.9999	Beer-Lambert law for semi-quantitative use
LOD	0.12 µg/mL (S/N ≥ 3:1)	Visual detection of characteristic bands
LOQ	0.37 µg/mL (S/N ≥ 10:1)	Lowest detectable functional group peak
Robustness	Flow rate ±0.1, MP ±5%, temp ±5°C; %RSD ≤ 1.2%	Variation in ATR pressure, thickness, scans

Procedure:

i. Record FTIR and HPLC spectra/chromatograms of pure reference standards.

ii. Place the prepared tablet sample on the ATR crystal or inject into the HPLC system as per optimized conditions.

iii. Collect the spectrum/chromatogram over the defined wavenumber or time range.

iv. Compare sample data with reference to identify characteristic peaks/peaks of zolmitriptan.

v. Observe any shifts, disappearance, or broadening of peaks indicating interactions with excipients.

vi. Calculate %RSD, % recovery, LOD, LOQ and compare against ICH acceptance criteria.

ASSAY OF ZOLMITRIPTAN TABLETS:

The validated RP-HPLC method was applied for the assay of commercially available zolmitriptan tablets. The sample solution was injected in triplicate and the percentage label claim was calculated as:

% Label Claim = (Peak Area of Sample / Peak Area of Standard) × (Std. Concentration / Sample Concentration) × 100

The percentage label claim was found to be 100.21 ± 0.68%, which is within the pharmacopoeial acceptance criteria of 95.0%–105.0%, confirming suitability for routine quantitative analysis.

FORCED DEGRADATION STUDIES:

Forced degradation studies were performed as per ICH Q1A(R2) to evaluate the stability-indicating capability of the RP-HPLC method. Zolmitriptan solutions were subjected to the following stress conditions:

1. Acid Hydrolysis: 0.1 N HCl at 60°C for 24 hours — minor degradation (~2.1%) observed.

2. Alkaline Hydrolysis: 0.1 N NaOH at 60°C for 24 hours — significant degradation (~8.4%) observed.

3. Oxidative Degradation: 3% H?O? at RT for 24 hours — moderate degradation (~5.7%) observed.

4. Photolytic Degradation: UV light (254 nm) for 48 hours — minor degradation (~1.8%) observed.

5. Thermal Degradation: 105°C for 24 hours — negligible degradation (<1.0%) observed.

In all stress conditions, degradation products were well-resolved from the principal peak of zolmitriptan, confirming the stability-indicating capability of the proposed method. The drug was found most susceptible to alkaline hydrolysis, followed by oxidative stress.

CONCLUSION:

The developed HPLC and ATR-FTIR methodology provides a rapid, reliable, and validated approach for the identification and quantitative determination of zolmitriptan in tablet dosage form. The RP-HPLC method demonstrated excellent linearity (r² = 0.9999, range 10–50 µg/mL), accuracy (99.12%–101.35% recovery), and precision (%RSD ≤ 0.85%), meeting all ICH Q2(R1) requirements. The ATR-FTIR method enabled functional group identification, verification of active ingredient identity, and monitoring of potential excipient interactions. Together, these methods ensure batch-to-batch consistency and serve as an effective quality control tool for comprehensive evaluation of zolmitriptan tablet formulations.

ACKNOWLEDGEMENTS:

The authors express sincere gratitude to [Name of Institution] for providing the necessary facilities and academic environment to carry out this work. Heartfelt thanks are conveyed to [Guide Name] for their invaluable guidance, constant encouragement, and constructive suggestions throughout the course of this study. Their expertise and continuous support were instrumental in the successful completion of this work.

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