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1.
Schizophr Res ; 2023 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-37487869

RESUMO

BACKGROUND: Up to 1/2 of outpatients prescribed clozapine may be partially/fully non-adherent, based on therapeutic drug monitoring (TDM). Three indices for measuring partial/full non-adherence are proposed a: 1) clozapine concentration/dose (C/D) ratio which drops to half or more of what is expected in the patient; 2) clozapine/norclozapine ratio that becomes inverted; and 3) clozapine concentration that becomes non-detectable. METHODS: These 3 proposed indices are based on a literature review and 17 cases of possible non-adherence from 3 samples: 1) an inpatient study in a Chinese hospital, 2) an inpatient randomized clinical trial in a United States hospital, and 3) and a Uruguayan outpatient study. RESULTS: The first index of non-adherence is a clozapine C/D ratio which is less than half the ratio corresponding to the patient's specific ancestry group and sex-smoking subgroup. Knowing the minimum therapeutic dose of the patient based on repeated TDM makes it much easier to establish non-adherence. The second index is inverted clozapine/norclozapine ratios in the absence of alternative explanations. The third index is undetectable concentrations. By using half-lives, the chronology of the 3 indices of non-adherence was modeled in two patients: 1) the clozapine C/D ratio dropped to ≥1/2 of what is expected from the patient (around day 2); 2) the clozapine/norclozapine ratio became inverted (around day 3); and 3) the clozapine concentration became undetectable by the laboratory (around days 9-11). CONCLUSION: Prospective studies should further explore these proposed clozapine indices in average patients, poor metabolizers (3 presented) and ultrarapid metabolizers (2 presented).

2.
Schizophr Res ; 2023 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-37268453

RESUMO

During weak induction (from smoking and/or valproate co-prescription), clozapine ultrarapid metabolizers (UMs) need very high daily doses to reach the minimum therapeutic concentration of 350 ng/ml in plasma; clozapine UMs need clozapine doses higher than: 1) 900 mg/day in patients of European/African ancestry, or 2) 600 mg/day in those of Asian ancestry. Published clozapine UMs include 10 males of European/African ancestry, mainly assessed with single concentrations. Five new clozapine UMs (two of European and three of Asian ancestry) with repeated assessments are described. A US double-blind randomized trial included a 32-year-old male smoking two packages/day with a minimum therapeutic dose of 1,591 mg/day from a single TDM during open treatment of 900 mg/day. In a Turkish inpatient study, a 30-year-old male smoker was a possible clozapine UM needing a minimum therapeutic dose of 1,029 mg/day estimated from two trough steady-state concentrations on 600 mg/day. In a Chinese study, three possible clozapine UMs (all male smokers) were identified. The clozapine minimum therapeutic dose estimated with trough steady-state concentrations >150 ng/ml was: 1) 625 mg/day, based on a mean of 20 concentrations in Case 3; 2) 673 mg/day, based on a mean of 4 concentrations in Case 4; and 3) 648 mg/day, based on a mean of 11 concentrations in Case 5. Based on these limited studies, clozapine UMs during weak induction may account for 1-2% of clozapine-treated patients of European ancestry and <1% of those of Asian ancestry. A clozapine-to-norclozapine ratio <0.5 should not be used to identify clozapine UMs.

3.
Br J Clin Pharmacol ; 86(8): 1661-1666, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32110830

RESUMO

Voriconazole is an antifungal metabolised by CYP2C19 enzyme, which can be inhibited by proton-pump inhibitors (PPIs). A prospective observational study was carried out to determine the influence of PPIs on voriconazole pharmacokinetic. The 78 patients included were divided into 4 groups: omeprazole (n = 32), pantoprazole (n = 25), esomeprazole (n = 3) and no PPI (n = 18). Patients with no PPI had no significant difference in plasma voriconazole concentration when compared with those with PPI (2.63 ± 2.13 µg/mL [95% confidence interval {CI} 1.57-3.69] vs 2.11 ± 1.73 µg/mL [95%CI 1.67-2.55], P > .05). However, voriconazole plasma concentration was significantly lower in patients treated with pantoprazole vs those treated with omeprazole (1.44 ± 1.22 µg/mL [95%CI 0.94-1.94) vs 2.67 ± 1.88 µg/mL [95%CI 2.02-3.32], P = .013) suggesting a greater CYP2C19 enzyme inhibitory effect of omeprazole. This study demonstrates the greater CYP inhibition capacity of omeprazole and should be helpful for the choice of PPIs for patients treated with voriconazole.


Assuntos
Omeprazol/uso terapêutico , Pantoprazol/uso terapêutico , Inibidores da Bomba de Prótons/uso terapêutico , Voriconazol/sangue , 2-Piridinilmetilsulfinilbenzimidazóis , Interações Medicamentosas , Inibidores Enzimáticos , Esomeprazol , Humanos , Estudos Prospectivos
5.
J Chemother ; 31(1): 49-57, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30580667

RESUMO

An observational retrospective study in patients treated with voriconazole was made to evaluate outcomes, safety, drug interactions and characteristics of the treatment. A total of 96 patients were included. In 78.12%, at least one inducer or enzyme inhibitor was detected. The most frequently observed potential interaction was the simultaneous administration of omeprazole. A large number of patients were concurrently treated with corticosteroids. The simultaneous administration of drugs acting as CYP450 enzyme inhibitors was associated with a higher risk of toxicity while concomitant administration of corticosteroids seemed a protective factor. Our study is one of the few ones, which evaluate the use of voriconazole in a real life clinical setting. We demonstrate the wide variety of strategies in the voriconazole using and the large number of dugs that are susceptible to pharmacokinetic interactions. This study reinforces the need to implement voriconazole pharmacokinetic monitoring in order to optimize antifungal treatment.


Assuntos
Antifúngicos/efeitos adversos , Micoses/tratamento farmacológico , Voriconazol/efeitos adversos , Adulto , Idoso , Idoso de 80 Anos ou mais , Antifúngicos/farmacocinética , Interações Medicamentosas , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Voriconazol/farmacocinética , Adulto Jovem
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