Analysis of Oseltamivir in Tamiflu Capsules Using Micellar Electrokinetic Chromatography

Abstract

1639Oseltamivir (Ro 64-0796 or GS4104) is an ethyl ester prodrug of oseltamivir carboxylate (Ro 64-0802 or GS4071) with the chemical name of ethyl (3R,4R,5S)4-acetylamino 5-amino-3(1-ethylpropoxy)1-cyclohexene-1-carboxylate phosphate (1 : 1). Its chemical structure is shown in Fig. 1. It inhibits neuraminidase activity in influenza A and B viruses. The activity of the enzyme is essential for the spread of infectious virus in the body. Oseltamivir is an effective therapeutic agent against pandemic influenza strains, including H5N1 that caused pandemics during recent years around the world. Since 2003, H5N1 has had a devastating impact on domestic and wild bird populations in many parts of Southeast Asia, Europe, the Middle East, and some parts of Africa. The virus was transmitted to humans, infecting more than 230 people, of whom over 50% died. 1)Oseltamivir is prescribed for both the treatment and prevention of influenza and is marketed as its phosphate salt by Roche Company under the trade name, Tamiflu ® . Tamiflu ® is available in both capsule and oral suspension formulations. In addition, the drug is supplied as an active pharmaceutical ingredient (API) for pandemic stockpiling. The API can be dissolved in water and distributed for widespread use in a pandemic outbreak. Brewster et al. showed the bioequivalence of API solution and capsule formulation.2) Oseltamivir is rapidly hydrolyzed in vivo to oseltamivir carboxylate by hepatic carboxylesterase. Both the prodrug and oseltamivir carboxylate are excreted unchanged in the urine.3) Bioassay,4) chromatographic methods with fluorescence, 5) mass spectrometric 6,7) and UV 8-13) detection have been described for the analysis of oseltamivir, but to the best of our knowledge, there is no report on the capillary electrophoresis (CE) method for the analysis of oseltamivir. To provide more information on the reported methods to analyze oseltamivir and its hydrolytic product, the related articles are briefly reviewed in chronological order. Eisenberg and Cundy 5) reported an HPLC method for the analysis of oseltamivir carboxylate in rat plasma using pre-column derivatization with naphthalendialdehyde and fluorescence detection. The recovery, limit of detection (LOD) and limit of quantification (LOQ) of their proposed method were 68%, 20 ng/ml and 50 ng/ml, respectively. 5) An HPLC-MS method was developed for analyses of oseltamivir phosphate and oseltamivir carboxylate in plasma and urine samples with LOQs of 1 and 10 ng/ml for the prodrug and the active compound, respectively.6) A simple and rapid analysis of oseltamivir was reported using the HPLC-UV method in Tamiflu capsules. 8)Another HPLC-UV method was presented for the analysis of oseltamivir phosphate in Tamiflu ® capsules and two generic versions of the drug. 9) None of these latter methods 8,9) dealt with the possibility of separation of oseltamivir carboxylate. Lindegårdh et al.7) developed a solid-phase extraction and gradient HPLC coupled with a tandom mass spectrometer for analyses of oseltamivir phospha...

MEKC as a powerful growing analytical technique

“…Until present, many publications have been reported describing the use of MEKC technique for pharmaceutical drug separation and determination from various pharmaceutical dosage forms ( e.g. for quality control) 231–239. In an infant formula, melamine was determined by using CE with online preconcentration techniques (FASS and sweeping), and the researcher concluded from the results that this study showed a great potential for the sweeping‐MEKC method as a tool for fast screening of melamine in infant formulas 239.…”

Micellar electrokinetic chromatography: A practical overview of current methodological and instrumental advances

“…This sweeping protocol has also been applied under basic conditions (BGE with borate buffer at pH over 8.5–10), but only three approaches have been reported. The first one, concerning the determination of picoxystrobin and pyraclostrobin in urine samples 37, the second one dealing with the analysis of the antiviral drug, oseltamivir, and its hydrolysed product in Tamiflu capsules 38 and the third one devoted to the determination of three neutral steroids (testosterone, progesterone and testosterone propionate) 39. As expected, the enhancement factors were lower than those obtained by the sweeping protocol in acidic medium (EOF suppression): only about a 15‐ to 20‐fold improvement in sensitivity can be achieved.…”

Spectrofluorimetric determination of oseltamivir phosphate through derivatization with o‐phthalaldehyde. Application to pharmaceutical preparations with a preliminary study on spiked plasma samples

“…These methods include: HPLC/UV detection or fluorescence detection after derivatization with naphthalenedialdehyde/potassium cyanide and HPLC–MS . Micellar electrokinetic chromatography and capillary zone electrophoresis were also applied for the determination of OST in capsules. Only two spectrophotometric methods with low sensitivity were developed for the determination of OST in capsule form .…”