In the recently published study by Blanco-Dorado et al, 1 the authors described two methods for determining plasma concentrations of voriconazole: high performance liquid chromatography (HPLC) and an ARK immunoassay. After correlation of the two methods and the concordance of the values was evaluated, it was noted that both methods could be implemented for therapeutic drug monitoring (TDM) of voriconazole to avoid hepatotoxicity and enable continued effective therapy for patients with invasive fungal infections. We strongly agree with the finding that the HPLC method was simple and fast, and can be easily applied for routine TDM of voriconazole. As a clinical pharmacist with more than 10 years' experience, I guide physicians and patients regarding voriconazole dosing, based on the results of TDM. There are several factors that need to be considered for the two methods in medical practice.
Firstly, the HPLC with ultraviolet method is limited to compounds that absorb ultraviolet light, characterised by the presence of the benzene ring or a conjugated structure. Hence this method is not suitable for determining concentrations of substances such as valproate and tacrolimus in human plasma. This is important for patients with epilepsy and those undergoing organ transplantation, to control symptoms and avoid attacking, except samples are taken derivative preparation.2
Secondly, our district tertiary general hospital in China has 1800 beds, and was passed as first class by the Jiangsu Commission of Health in 2017. TDM is carried out in the department of pharmacy of our hospital to improve the quality of pharmaceutical care. Because of the complexity of the HPLC instrument, the operator needs good skills and a quick response. Also, development and validation of a HPLC method for TDM requires standard samples.
Lastly, there are various methods used for TDM, including bioassays and HPLC with ultraviolet detection or mass spectrometry. In accordance with operating standards, bioassays are simpler than HPLC. HPLC devices, especially with mass spectrometry, are not always available because of their high costs, and immunoassays may be carried out in general hospitals in rural areas or in community hospitals. However, when combination therapy is being used for the treatment of invasive antifungal infections, bioassays lack sensitivity and specificity compared with HPLC.3
We agree with the authors’ conclusion that HPLC is more sensitive than the immunoassay method. The inspiring outcomes from the study of Blanco-Dorado et al 1 will encourage pharmacists to choose different analytical methods in different situations.
Footnotes
Funding: The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests: None declared.
Patient consent for publication: Not required.
Provenance and peer review: Not commissioned; internally peer reviewed.
References
- 1. Blanco-Dorado S, Belles Medall MD, Pascual-Marmaneu O, et al. Therapeutic drug monitoring of voriconazole: validation of a high performance liquid chromatography method and comparison with an ARK immunoassay. Eur J Hosp Pharm 2020doi: 10.1136/ejhpharm-2019-002155. [Epub ahead of print 9 March 2020] 10.1136/ejhpharm-2019-002155 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2. Wei H, Ting Z, Yongchang W, et al. Pre-column derivatization-ultra-high performance liquid chromatography method for the determination of sodium valproate concentration in human serum[J]. Chin J Clin Pharm 2013;22:342–5. [Google Scholar]
- 3. Hamada Y, Tokimatsu I, Mikamo H, et al. Practice guidelines for therapeutic drug monitoring of voriconazole: a consensus review of the Japanese Society of Chemotherapy and the Japanese Society of Therapeutic Drug Monitoring. J Infect Chemother 2013;19:381–92. 10.1007/s10156-013-0607-8 [DOI] [PMC free article] [PubMed] [Google Scholar]