Therapeutic Drug Monitoring of Pazopanib in Renal Cell Carcinoma and Soft Tissue Sarcoma: A Systematic Review.

BACKGROUND: Pazopanib, an anti-angiogenic multitarget tyrosine kinase inhibitor, has been approved for the treatment of metastatic renal cell carcinoma and soft tissue sarcoma. However, its recommended dose does not always produce consistent outcomes, with some patients experiencing adverse effects or toxicity. This variability is due to differences in the systemic exposure to pazopanib. This review aimed to establish whether sufficient evidence exists for the routine or selective therapeutic drug monitoring of pazopanib in adult patients with approved indications. METHODS: A systematic search of the PubMed and Web of Science databases using search terms related to pazopanib and therapeutic drug monitoring yielded 186 and 275 articles, respectively. Ten articles associated with treatment outcomes or toxicity due to drug exposure were selected for review. RESULTS: The included studies were evaluated to determine the significance of the relationship between drug exposure/Ctrough and treatment outcomes and between drug exposure and toxicity. A relationship between exposure and treatment outcomes was observed in 5 studies, whereas the trend was nonsignificant in 4 studies. A relationship between exposure and toxicity was observed in 6 studies, whereas 2 studies did not find a significant relationship; significance was not reported in 3 studies. CONCLUSIONS: Sufficient evidence supports the therapeutic drug monitoring of pazopanib in adult patients to improve its efficacy and/or safety in the approved indications.

High vs. low-dose leucovorin in regimens with fluorouracil in colorectal cancer therapy.

The problem of unavailability of drugs and shortages have been a common problem in recent years. Shortages may threaten some treatment regimens for oncological patients. This article presents a systematic review of studies evaluating the efficacy and safety of chemotherapy regimens combining fluorouracil and standard or low-dose leucovorin in treating colorectal cancer. A total of 13 prospective and retrospective studies were included in the review. Meta-analyses and review papers were excluded. It is apparent from the systematic review that a lower dose of leucovorin does not fundamentally affect the efficacy of regimens combining 5-fluorouracil with leucovorin in treating patients with colorectal cancer. Similarly, even in the case of safety, reducing the dose of leucovorin did not influence the frequency and severity of observed adverse effects. Surprisingly, in three studies, some of the adverse effects occurred more often with the higher dose of leucovorin. Furthermore, the article presents the results of a questionnaire survey of the management of leucovorin shortages at the departments of preparation of cytostatics (N = 46) within the Czech Republic. In total, 35 workplaces provided feedback. In 17 cases, the departments for the preparation of cytostatics in the Czech Republic had to accept restrictions on administering the full dose of leucovorin. These restrictions consisted of reducing the dose of the injectable form of leucovorin, changing the chemotherapy regimen, administering the oral form of calcium folinate, forcing a therapeutic break, or a combination of these approaches.

Therapeutic Drug Monitoring of Sunitinib in Gastrointestinal Stromal Tumors and Metastatic Renal Cell Carcinoma in Adults-A Review.

BACKGROUND: Sunitinib is an inhibitor of multiple receptor tyrosine kinases and is a standard-of-care treatment for advanced and metastatic renal cell carcinoma and a second-line treatment in locally advanced inoperable and metastatic gastrointestinal stromal tumors. A fixed dose of the drug, however, does not produce a uniform therapeutic outcome in all patients, and many face adverse effects and/or toxicity. One of the possible causes of the interindividual variability in the efficacy and toxicity response is the highly variable systemic exposure to sunitinib and its active metabolite. This review aims to summarize all available clinical evidence of the treatment of adult patients using sunitinib in approved indications, addressing the necessity to introduce proper and robust therapeutic drug monitoring (TDM) of sunitinib and its major metabolite, N-desethylsunitinib. METHODS: The authors performed a systematic search of the available scientific literature using the PubMed online database. The search terms were "sunitinib" AND "therapeutic drug monitoring" OR "TDM" OR "plasma levels" OR "concentration" OR "exposure." The search yielded 520 journal articles. In total, 447 publications were excluded because they lacked sufficient relevance to the reviewed topic. The remaining 73 articles were, together with currently valid guidelines, thoroughly reviewed. RESULTS: There is sufficient evidence confirming the concentration-efficacy and concentration-toxicity relationship in the indications of gastrointestinal stromal tumors and metastatic renal clear-cell carcinoma. For optimal therapeutic response, total (sunitinib + N-desethylsunitinib) trough levels of 50-100 ng/mL serve as a reasonable target therapeutic range. To avoid toxicity, the total trough levels should not exceed 100 ng/mL. CONCLUSIONS: According to the current evidence presented in this review, a TDM-guided dose modification of sunitinib in selected groups of patients could provide a better treatment outcome while simultaneously preventing sunitinib toxicity.

Quantification of selected antidepressants and antipsychotics in clinical samples using chromatographic methods combined with mass spectrometry: A review (2006-2015).

BACKGROUND: Psychiatric disorders contribute significantly to worldwide morbidity and mortality. In the case of depression and schizophrenia, effective drug therapy is available but 30-50% of patients do not respond sufficiently to the initial treatment regimen. Apart from the development of new molecules, it is desirable to optimize treatment outcomes with agents that are currently available. Therapeutic drug monitoring (TDM) is a suitable and widely accepted approach for improving the efficacy and safety of these drugs. METHODS: A review of the relevant literature published between 2006 and January 2015. RESULTS AND CONCLUSIONS: This review describes major advances and drawbacks in the field of chromatography coupled with single or tandem mass spectrometry (LC-MS, LC-MS/MS and GC/MS) of selected antidepressants (agomelatine, vilazodone) and antipsychotics (iloperidone, asenapine, amisulpride, aripiprazole, melperone, zotepine, ziprasidone). The high specificity in combination with high sensitivity makes these techniques an attractive complementary method to traditional procedures used in routine practice for TDM.

Cannabinoids and Cytochrome P450 Interactions.

OBJECTIVE: This review consists of three parts, representing three different possibilities of interactions between cannabinoid receptor ligands of both exogenous and endogenous origin and cytochrome P450 enzymes (CYPs). The first part deals with cannabinoids as CYP substrates, the second summarizes current knowledge on the influence of various cannabinoids on the metabolic activity of CYP, and the third outline a possible involvement of the endocannabinoid system and cannabinoid ligands in the regulation of CYP liver activity. METHODS: We performed a structured search of bibliographic and drug databases for peer-reviewed literature using focused review questions. RESULTS: Biotransformation via a hydrolytic pathway is the major route of endocannabinoid metabolism and the deactivation of substrates is characteristic, in contrast to the minor oxidative pathway via CYP involved in the bioactivation reactions. Phytocannabinoids are extensively metabolized by CYPs. The enzymes CYP2C9, CYP2C19, and CYP3A4 catalyze most of their hydroxylations. Similarly, CYP represents a major metabolic pathway for both synthetic cannabinoids used therapeutically and drugs that are abused. In vitro experiments document the mostly CYP inhibitory activity of the major phytocannabinoids, with cannabidiol as the most potent inhibitor of many CYPs. The drug-drug interactions between cannabinoids and various drugs at the CYP level are reported, but their clinical relevance remains unclear. The direct activation/inhibition of nuclear receptors in the liver cells by cannabinoids may result in a change of CYP expression and activity. Finally, we hypothesize the interplay of central cannabinoid receptors with numerous nervous systems, resulting in a hormone-mediated signal towards nuclear receptors in hepatocytes.