Abstract
A rapid and stability-indicating RP-HPLC method was developed for determination of l-carnitine in tablets. The separation was based on a C18 analytical column using a mobile phase which consisted of 0.05 M phosphate buffer (pH = 3): ethanol (99 : 1), including 0.56 mg/mL of sodium 1-heptanesulfonate. Column temperature was set at 50°C and quantitation was achieved by UV detection at 225 nm. In forced degradation studies, the drug was subjected to oxidation, hydrolysis, photolysis, and heat. Among the different stress conditions, the exposure to acidic and basic conditions was found to be an important adverse stability factor. The method was validated for specificity, selectivity, linearity, precision, accuracy, and robustness. The applied procedure was found to be linear in l-carnitine concentration range of 84.74–3389.50 µg/mL (r 2 = 0.9997). Precision was evaluated by replicate analysis in which relative standard deviation (RSD) values for areas were found below 2.0%. The recoveries obtained (100.83%–101.54%) ensured the accuracy of the developed method. The expanded uncertainty (3.14%) of the method was also estimated from method validation data. Accordingly, the proposed validated and rapid procedure was proved to be suitable for routine analyzing and stability studies of l-carnitine in tablets.
Highlights
Introduction lCarnitine ((R)-3-carboxy-2-hydroxy-N,N,N-trimethyl-1propaminium hydroxide inner salt, Figure 1(a)) is a vitaminlike amino acid derivative, which is an essential factor in fatty acid metabolism as acyltransferase cofactor and in energy production processes, such as interconversion in the mechanisms of regulation of ketogenesis and thermogenesis
The stability-indicating and rapid RP-HPLC method developed for the quantitative analysis of l-carnitine in pharmaceutical dosage forms is precise, linear, accurate, specific, and robust
To the best of our knowledge, this is the first method which reports the metrological parameters in quantification of l-carnitine in pharmaceutical tablets
Summary
Introduction lCarnitine ((R)-3-carboxy-2-hydroxy-N,N,N-trimethyl-1propaminium hydroxide inner salt, Figure 1(a)) is a vitaminlike amino acid derivative, which is an essential factor in fatty acid metabolism as acyltransferase cofactor and in energy production processes, such as interconversion in the mechanisms of regulation of ketogenesis and thermogenesis. The method for tablets involves an aminopropylsilane-bonded silica gel column, acetonitrile-phosphate buffer (pH 4.7) mobile phase, and detection at 205 nm. This method requires a prolonged equilibration of the column (6 h), which is time consuming in case the formulation contains an organic acid, due to the long retention time of the acid under the specified HPLC conditions [5]. For solution formulations, USP presents an HPLC method using ion-pairing modifiers. This method cannot separate crotonoylbetaine (impurity A) (Figure 1(b)), a major impurity and degradation product, from l-carnitine [6]. Other reported methods for quantification of l-carnitine in tablets are limited in either low sensitivity for dissolution testing or not being stability-indicating [5,6,7,8]
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