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1.
Eur J Haematol ; 112(3): 360-366, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37821211

RESUMO

Novel therapies for multiple myeloma (MM) have improved patient survival, but their high costs strain healthcare budgets. End-of-life phases of treatment are generally the most expensive, however, these high costs may be less justifiable in the context of a less pronounced clinical benefit. To manage drug expenses effectively, detailed information on end-of-life drug administration and costs are crucial. In this retrospective study, we analysed treatment sequences and drug costs from 96 MM patients in the Netherlands who died between January 2017 and July 2019. Patients received up to 16 lines of therapy (median overall survival: 56.5 months), with average lifetime costs of €209 871 (€3111/month; range: €3942-€776 185) for anti-MM drugs. About 85% of patients received anti-MM treatment in the last 3 months before death, incurring costs of €20 761 (range: €70-€50 122; 10% of total). Half of the patients received anti-MM treatment in the last 14 days, mainly fully oral regimens (66%). End-of-life treatment costs are substantial despite limited survival benefits. The use of expensive treatment options is expected to increase costs further. These data serve as a reference point for future cost studies, and further research is needed to identify factors predicting the efficacy and clinical benefit of continuing end-of-life therapy.


Assuntos
Mieloma Múltiplo , Humanos , Mieloma Múltiplo/diagnóstico , Mieloma Múltiplo/tratamento farmacológico , Custos de Medicamentos , Estudos Retrospectivos , Custos de Cuidados de Saúde , Morte , Análise Custo-Benefício
2.
J Virol ; 96(17): e0072322, 2022 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-35975999

RESUMO

The production of type I interferon (IFN) is the hallmark of the innate immune response. Most, if not all, mammalian viruses have a way to circumvent this response. Fundamental knowledge on viral evasion of innate immune responses may facilitate the design of novel antiviral therapies. To investigate how human metapneumovirus (HMPV) interacts with the innate immune response, recombinant viruses lacking G, short hydrophobic (SH), or M2-2 protein expression were assessed for IFN induction in A549 cells. HMPV lacking G or SH protein expression induced similarly low levels of IFN, compared to the wild-type virus, whereas HMPV lacking M2-2 expression induced significantly more IFN than the wild-type virus. However, sequence analysis of the genomes of M2-2 mutant viruses revealed large numbers of mutations throughout the genome. Over 70% of these nucleotide substitutions were A-to-G and T-to-C mutations, consistent with the properties of the adenosine deaminase acting on RNA (ADAR) protein family. Knockdown of ADAR1 by CRISPR interference confirmed the role of ADAR1 in the editing of M2-2 deletion mutant virus genomes. More importantly, Northern blot analyses revealed the presence of defective interfering RNAs (DIs) in M2-2 mutant viruses and not in the wild-type virus or G and SH deletion mutant viruses. DIs are known to be potent inducers of the IFN response. The presence of DIs in M2-2 mutant virus stocks and hypermutated virus genomes interfere with studies on HMPV and the innate immune response and should be addressed in future studies. IMPORTANCE Understanding the interaction between viruses and the innate immune response is one of the barriers to the design of antiviral therapies. Here, we investigated the role of the G, SH, and M2-2 proteins of HMPV as type I IFN antagonists. In contrast to other studies, no IFN-antagonistic functions could be observed for the G and SH proteins. HMPV with a deletion of the M2-2 protein did induce type I IFN production upon infection of airway epithelial cells. However, during generation of virus stocks, these viruses rapidly accumulated DIs, which are strong activators of the type I IFN response. Additionally, the genomes of these viruses were hypermutated, which was prevented by generating stocks in ADAR knockdown cells, confirming a role for ADAR in hypermutation of HMPV genomes or DIs. These data indicate that a role of the HMPV M2-2 protein as a bona fide IFN antagonist remains elusive.


Assuntos
Imunidade Inata , Interferon Tipo I , Metapneumovirus , Proteínas Virais , Células A549 , Adenosina Desaminase , Antivirais/metabolismo , Humanos , Interferon Tipo I/antagonistas & inibidores , Interferon Tipo I/imunologia , Metapneumovirus/genética , Metapneumovirus/metabolismo , Proteínas de Ligação a RNA , Proteínas Virais/genética , Proteínas Virais/metabolismo
5.
Cancer Manag Res ; 11: 2663-2675, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31037034

RESUMO

Although the prognosis of multiple myeloma (MM) patients has dramatically improved during recent years, virtually all patients eventually develop relapsed refractory disease. Several new therapeutics have been developed in the last few years, including carfilzomib, a second-generation proteasome inhibitor (PI) that has been approved by the US Food and Drug Administration (FDA) in the setting of relapsed and/or refractory MM, as a single agent with or without dexamethasone, and in combination with lenalidomide in 2012 and 2015, respectively. Other promising combinations with carfilzomib are being investigated. Carfilzomib has shown superiority over the first-generation PI bortezomib on both efficacy and toxicity. In particular, profoundly lower incidence in polyneuropathy compared to bortezomib has been described. However, carfilzomib has a different toxicity profile, with more cardiovascular adverse events. Therefore, caution should be taken with the use of carfilzomib for elderly and cardiovascularly compromised patients. The once-weekly administration of carfilzomib, recently approved by the FDA in combination with dexamethasone, will lead to a lower burden for the patient and caregivers compared to the twice-weekly schemes that were routinely used until recently. This review has a focus on clinical trial data that has led to drug approval, as well as new promising combination studies, and provides advice for treating physicians who are now prescribing this drug to patients.

6.
Semin Oncol Nurs ; 15(1): 48-57, 1999 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10074657

RESUMO

OBJECTIVES: To review liver physiology, the disease process, diagnostic tests, and current treatment options for primary and metastatic liver cancer. DATA SOURCES: Research studies, review articles, and textbooks relating to liver cancer. CONCLUSIONS: Surgical resection offers the best available treatment modality, but only a small percentage of patients are eligible. However, combined treatment of radiation therapy and chemotherapy (systemic and intra-arterial), as well as chemoembolization, cryosurgery, and transplantation, offers hope of palliation, conversion of unresectable to resectable disease, and prolonged survival. IMPLICATIONS FOR NURSING PRACTICE: Understanding and knowledge of the disease process and treatment modalities for primary and metastatic liver cancer will assist the oncology nurse in educating patients and families during their diagnostic and treatment phases.


Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Adulto , Idoso , Carcinoma Hepatocelular/epidemiologia , Carcinoma Hepatocelular/enfermagem , Carcinoma Hepatocelular/patologia , Carcinoma Hepatocelular/terapia , Feminino , Humanos , Fígado/anatomia & histologia , Fígado/fisiologia , Neoplasias Hepáticas/epidemiologia , Neoplasias Hepáticas/enfermagem , Neoplasias Hepáticas/patologia , Neoplasias Hepáticas/secundário , Neoplasias Hepáticas/terapia , Masculino , Estadiamento de Neoplasias , Fatores de Risco , Apoio Social
7.
Clin Exp Dermatol ; 23(3): 103-8, 1998 May.
Artigo em Inglês | MEDLINE | ID: mdl-9861736

RESUMO

Majocchi's granuloma is a folliculitic and perifolliculitic dermatophyte infection of the dermis, a site that is not generally colonized by fungi in immunocompetent individuals. Topical agents are usually ineffective therapeutically because of the deep location of the infection. The objective of this study was to determine the effectiveness of oral itraconazole. We also examined the pharmacokinetics of the drug in scalp hair during pulse therapy. This information would then be useful in determining the efficacy of itraconazole administered by means of intermittent pulse dosing in the treatment of tinea capitis. Seven patients (age range 25-75 years) were treated up to three times with itraconazole pulse therapy, 200 mg twice daily for 1 week, with 2 weeks off between pulses. Samples of scalp hair and plasma were also obtained to determine the pharmacokinetics of the drug at these two sites. All seven patients responded to therapy, clinical and mycological cure being achieved after one pulse (one patient), two pulses (three patients), or three pulses (three patients, each with toenail onychomycosis); none relapsed over a 6-18-month follow-up period. In all six patients who received two or more pulses of itraconazole, almost complete cure was observed before the second pulse, with full resolution within 2 weeks of its completion. Itraconazole was also detected in the hair after 1 week, and at concentrations 2.6-fold and 3.4-fold higher, respectively, after the second and third pulses. After the discontinuation of therapy, itraconazole was then detectable in the hair for 9 months, at least in a female patient who did not have her hair cut. Two pulses of oral itraconazole therapy thus appear to be effective in the treatment of Majocchi's granuloma, and it is possible that one pulse may be sufficient in some patients. These data suggest that itraconazole pulse therapy should be effective in the treatment of tinea capitis.


Assuntos
Antifúngicos/uso terapêutico , Granuloma/tratamento farmacológico , Itraconazol/uso terapêutico , Tinha/tratamento farmacológico , Adulto , Idoso , Antifúngicos/farmacocinética , Esquema de Medicação , Feminino , Granuloma/metabolismo , Humanos , Itraconazol/farmacocinética , Masculino , Pessoa de Meia-Idade , Tinha/metabolismo , Tinha do Couro Cabeludo/tratamento farmacológico , Tinha do Couro Cabeludo/metabolismo
8.
Anesth Analg ; 86(2): 361-6, 1998 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-9459249

RESUMO

UNLABELLED: We investigated the pharmacokinetics of the enantiomers of bupivacaine and mepivacaine after epidural injection of the racemate of each drug into six surgical patients. After epidural administration of either bupivacaine/HCl (115 mg) or mepivacaine/HCl (460 mg), blood samples were collected for 24 h. Unbound fractions were determined by using ultrafiltration for bupivacaine and equilibrium dialysis for mepivacaine. Concentrations in plasma, ultrafiltrate, and dialysate were determined by using stereoselective high-performance liquid chromatography. Peak plasma concentrations of R(+)-bupivacaine (389 +/- 93 ng/mL) and R(-)-mepivacaine (1350 +/- 430 ng/mL) were smaller than those of S(-)-bupivacaine (449 +/- 109 ng/mL, P < 0.0001) and S(+)-mepivacaine (1740 +/- 490 ng/mL, P < 0.002), respectively. However, the unbound peak concentrations of R(+)-bupivacaine (20 +/- 11 ng/mL) were larger than those of S(-)-bupivacaine (15 +/- 9 ng/mL, P < 0.005); unbound peak concentrations of R(-)-mepivacaine (485 +/- 158 ng/mL) and S(+)-mepivacaine (460 +/- 139 ng/mL) did not differ. These observations reflect differences in the systemic disposition (distribution and elimination) of the enantiomers, because the systemic absorption was not enantioselective with either drug. This study supports the opinion that the use of single enantiomers, rather than racemates, is preferable, particularly for bupivacaine. IMPLICATIONS: Measurements of the plasma concentrations of the enantiomers of bupivacaine and mepivacaine after epidural administration of the racemates demonstrated that the systemic disposition, but not the systemic absorption, of these drugs is enantioselective and supports the opinion that the use of single enantiomers, rather than racemates, is preferable.


Assuntos
Bupivacaína/farmacocinética , Mepivacaína/farmacocinética , Adulto , Área Sob a Curva , Bupivacaína/química , Humanos , Injeções Epidurais , Injeções Intravenosas , Mepivacaína/química , Pessoa de Meia-Idade , Estereoisomerismo , Relação Estrutura-Atividade
9.
J Pharmacol Toxicol Methods ; 38(2): 59-69, 1997 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9403776

RESUMO

Precision-cut liver slices are presently used for various research objects, e.g. to study metabolism, transport, and toxicity of xenobiotics. Various incubation systems are presently employed, but a systematic comparison between these incubation systems with respect to preservation of slice function has not been performed yet. Therefore, we started a comparative study to evaluate five of these systems: the shaken flask (an Erlenmeyer in a shaking water bath), the stirred-well (24-well culture plate equipped with grids and magnetic stirrers), rocker platform (6-well culture plate with Netwell insert rocked on a platform), the roller system (dynamic organ culture rolled on an insert in a glass vial), and the 6-well shaker (6-well culture plate in a shaking water bath). The liver slices were incubated in these incubation systems for 0.5, 1.5, and 24.5 h and subsequently subjected to viability and metabolic function tests. The viability of the incubated liver slices was evaluated by: potassium content, MTT assay, energy charge, histomorphology, and LDH leakage. Their metabolic functions were studied by determination of the metabolism of lidocaine, testosterone, and antipyrine. Up to 1.5 h of incubation all five incubation systems gave similar results with respect to viability and metabolic function of the liver slices. However, after 24 h, the shaken flask, the rocker platform, and the 6-well shaker incubation systems appeared to be superior to the stirred well and the roller incubation systems.


Assuntos
Fígado/metabolismo , Técnicas de Cultura de Órgãos/métodos , Xenobióticos/metabolismo , Animais , Metabolismo Energético/fisiologia , L-Lactato Desidrogenase/metabolismo , Fígado/química , Fígado/enzimologia , Masculino , Técnicas de Cultura de Órgãos/instrumentação , Potássio/metabolismo , Ratos , Ratos Wistar
10.
Anesth Analg ; 84(1): 85-9, 1997 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-8989005

RESUMO

The pharmacokinetics of R(-)-mepivacaine and S(+)-mepivacaine were investigated in 10 healthy volunteers. The volunteers received racemic mepivacaine, hydrochloride (dose 60 mg) via a 10-min intravenous infusion. Blood samples were collected at gradually increasing intervals until 8 h after the start of the infusion. Plasma concentrations of the enantiomers were determined with a stereoselective high-performance liquid chromatographic (HPLC) method. Unbound fractions of the enantiomers were determined using equilibrium dialysis. The unbound fraction of R(-)-mepivacaine (mean +/- SD: 35.6% +/- 4.5%) was larger (P < 0.0001) than that of S(+)-mepivacaine (25.1% +/- 4.6%). The total plasma clearance and steady-state volume of distribution of R(-)-mepivacaine, based on total plasma concentrations (total plasma clearance [CL] = 0.79 +/- 0.12 L/min; volume of distribution at steady state [VSS] = 103 +/- 14 L) as well as on unbound plasma concentrations (plasma clearance of unbound drug [CLu] = 2.24 +/- 0.30 L/min; volume of distribution of unbound drug at steady state [Vuss] = 290 +/- 32 L), were larger (P < 0.0001) than those of S(+)-mepivacaine (CL = 0.35 +/- 0.06 L/min; Vss = 57 +/- 7 L; CLu = 1.43 +/- 0.24 L/ min; Vuss = 232 +/- 30 L). The terminal half-life (t1/2,Z) and mean residence time (MRT) of R(-)-mepivacaine (t1/2,Z = 113 +/- 17 min; MRT = 131 +/- 15 min) were shorter than those of S(+)-mepivacaine (t1/2,Z = 123 +/- 20 min, P < 0.02; MRT = 165 +/- 24 min, P < 0.0001). This study demonstrated a marked difference in the pharmacokinetics of the enantiomers of mepivacaine. The stereoselectivity can be partially explained by a difference in the plasma protein binding of the enantiomers.


Assuntos
Anestésicos Locais/farmacocinética , Mepivacaína/farmacocinética , Adulto , Anestésicos Locais/administração & dosagem , Humanos , Infusões Intravenosas , Masculino , Mepivacaína/administração & dosagem , Estereoisomerismo
11.
Antimicrob Agents Chemother ; 41(12): 2714-8, 1997 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-9420044

RESUMO

Pharmacokinetics and safety of a hydroxy-beta-propyl solution of itraconazole were assessed in 16 patients in an intensive care unit. On the first 2 days, four 1-h infusions of 200 mg were given at 0, 8, 24, and 32 h. From day 3 to 7, inclusive, a single 1-h infusion of 200 mg of itraconazole was given daily. The intravenous (i.v.) treatment was directly followed by repeated administrations of an oral solution of itraconazole at a dosage of either 200 mg once daily or 200 mg twice daily (b.i.d.). During i.v. treatment, steady-state concentrations of itraconazole and hydroxy-itraconazole in plasma were reached within 48 and 96 h, respectively. At the end of i.v. treatment, mean (+/- standard deviation) itraconazole and hydroxy-itraconazole trough concentrations in plasma were 0.344 +/- 0.140 and 0.605 +/- 0.205 microg/ml, respectively. After the 2-week oral follow-up of 200 mg once daily the mean trough concentration had decreased to 0.245 microg/ml, whereas after 200 mg b.i.d. it increased to 0.369 microg/ml. Diarrhea during oral treatment appeared to be dose related and may be due to the solvent hydroxypropyl-beta-cyclodextrin. More severe laboratory abnormalities were noted during the i.v. than the oral treatment phase, probably related to more severe illness in that period of intensive care, but none proved clinically important. These results suggest that plasma itraconazole levels above 0.250 microg/ml may be achieved and maintained with the 1-week i.v. schedule followed by b.i.d. oral administration, whereas the once-daily oral follow-up seems to be a suboptimal treatment.


Assuntos
Antifúngicos/efeitos adversos , Antifúngicos/sangue , Itraconazol/efeitos adversos , Itraconazol/sangue , beta-Ciclodextrinas , 2-Hidroxipropil-beta-Ciclodextrina , Adolescente , Adulto , Antifúngicos/uso terapêutico , Ciclodextrinas/administração & dosagem , Esquema de Medicação , Feminino , Humanos , Infusões Intravenosas , Unidades de Terapia Intensiva , Itraconazol/análogos & derivados , Itraconazol/uso terapêutico , Masculino , Pessoa de Meia-Idade , Micoses/prevenção & controle , Soluções
12.
J Vet Pharmacol Ther ; 19(5): 364-9, 1996 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8905570

RESUMO

The bioavailability of penicillin and dihydrostreptomycin from three penicillin/ aminoglycoside fixed combination products for intramuscular injection was investigated in a four-way, randomized, crossover experiment in rabbits. Attention is focused on bioequivalence based on plasma concentration vs. time profiles to study whether the rabbit is a good model to detect differences in in vivo delivery of penicillin and/or dihydrostreptomycin after intramuscular administration of different products. In all products, penicillin was present as a suspension. Although the extent of absorption of penicillin did not differ between the three products, large differences in the rates of absorption were observed. With respect to dihydrostreptomycin, no significant differences were observed between the products. The results from this study demonstrate that the rabbit is a good model to detect differences in bioavailability of suspended penicillin from penicillin /dihydrostreptomycin fixed combination products for intramuscular injection. A study with the same products is presently being carried out in calves to investigate whether bioequivalence studies in rabbits could replace studies in the target animals.


Assuntos
Antibacterianos/farmacocinética , Sulfato de Di-Hidroestreptomicina/farmacocinética , Injeções Intramusculares/veterinária , Penicilinas/farmacocinética , Absorção , Análise de Variância , Animais , Antibacterianos/administração & dosagem , Antibacterianos/sangue , Disponibilidade Biológica , Estudos Cross-Over , Sulfato de Di-Hidroestreptomicina/administração & dosagem , Sulfato de Di-Hidroestreptomicina/sangue , Feminino , Meia-Vida , Injeções Intramusculares/normas , Injeções Intravenosas/veterinária , Penicilinas/administração & dosagem , Penicilinas/sangue , Coelhos , Equivalência Terapêutica
13.
J Vet Pharmacol Ther ; 19(5): 370-5, 1996 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8905571

RESUMO

A bioequivalence study with three penicillin/dihydrostreptomycin fixed combination products for intramuscular administration was performed in dairy calves. In addition to plasma concentrations of penicillin and dihydrostreptomycin, creatine phosphokinase concentrations were determined during a period of 72 h after administration of the drug products. Considerable differences were observed in the pharmacokinetics of penicillin from the three products. Although the extent of absorption was similar for all products, one product showed a significantly slower release from the site of injection. Except for the AUC, the 90% confidence intervals for these parameters exceeded the acceptable range of 0.80-1.20. Therefore, these products are not bioequivalent with respect to the rate of absorption of penicillin. Concerning the pharmacokinetics of dihydrostreptomycin in calves, it could not be concluded that the products were bioequivalent, since the 90% confidence intervals of the ratios for Cmax, tmax and MRT exceeded the range of 0.80-1.20. From this study in calves, it was also found that the product with the slowest release of penicillin from the injection site caused the most severe tissue damage, based on plasma creatine phosphokinase concentrations. Comparing the results from this study in calves with those from a previous study in rabbits, it can be concluded that the rabbit is a good animal model that could substitute for large animals, at least calves, in bioequivalence studies for penicillin/dihydrostreptomycin fixed combination products.


Assuntos
Antibacterianos/farmacocinética , Sulfato de Di-Hidroestreptomicina/farmacocinética , Injeções Intramusculares/normas , Penicilinas/farmacocinética , Análise de Variância , Animais , Antibacterianos/administração & dosagem , Antibacterianos/sangue , Creatina Quinase/sangue , Sulfato de Di-Hidroestreptomicina/administração & dosagem , Sulfato de Di-Hidroestreptomicina/sangue , Relação Dose-Resposta a Droga , Feminino , Injeções Intramusculares/veterinária , Testes de Sensibilidade Microbiana , Penicilinas/administração & dosagem , Penicilinas/sangue , Equivalência Terapêutica
14.
J Chromatogr B Biomed Appl ; 678(2): 369-72, 1996 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-8738046

RESUMO

A method enabling quantification of R-(-)- and S-(+)-mepivacaine in human plasma in the low nanogram per milliliter range is described. The procedure involves extraction from plasma with diethyl ether, centrifugation, back-extraction into an acidified aqueous solution, washing with a mixture of pentane and isoamylalcohol, alkalinisation, followed by extraction with a mixture of n-pentane and isoamylalcohol. After evaporation of the organic phase, the residue is redissolved in the mobile phase used for the HPLC analysis, which consists of a 6.8:93.2 (v/v) isopropanol-sodium hydrogenphosphate buffer solution with the pH adjusted to 6.8 using phosphoric acid. The HPLC method has been described previously. Separation of the enantiomers is achieved with an alpha 1-AGP column and the UV detection wavelength is 210 nm. The minimal detectable concentration is ca. 3 ng/ml and the lower limit of quantification is 5 ng/ml for each enantiomer. For both enantiomers r is > 0.9995 over the plasma enantiomeric concentration range of 10.5-1053 ng/ml.


Assuntos
Anestésicos Locais/sangue , Cromatografia Líquida de Alta Pressão/métodos , Mepivacaína/sangue , Cromatografia Líquida de Alta Pressão/estatística & dados numéricos , Humanos , Microquímica , Análise de Regressão , Estereoisomerismo
16.
J Pharmacol Exp Ther ; 274(1): 143-7, 1995 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-7616391

RESUMO

The influence of ageing and dietary restriction (DR) on the in vivo activities of different P450 enzymes was studied longitudinally in female BN/BiRij rats. For this purpose, antipyrine (AP) and theophylline (TH) were used as substrates. The metabolic clearances of AP (CIm AP) and TH (CIm TH) were used as indicators for P450 enzyme activities in vivo. Therefore, we also included the assessment of the clearances of formation of three AP metabolites, i.e., 3-hydroxymethylantipyrine (CI-->HMA), 4-hydroxyantipyrine (CI-->OHA) and norantipyrine (CI-->NORA). Ninety, 50 and 10% survival times were prolonged significantly in DR rats. In control animals, the contribution to the metabolism of AP in the formation of HMA, OHA and NORA, expressed as percentage of the dose, decreased with ageing, indicating that other pathways compensate for this decrease. Only a significant decrease in the metabolism to OHA was observed in DR animals. CI-->HMA, CI-->OHA and CI-->NORA showed an age-related decrease in the control rats, whereas in the DR rats an age-related decrease was observed for CI-->HMA and CI-->OHA. The results of the present study suggest that the decrease in the activities of the P450 enzymes involved in the formation of HMA, OHA and NORA have a later onset in the DR rats. In conclusion, DR not only has a strong positive influence on the health and life span of the rats, but also results in a delayed onset of the decrease in activity of certain P450 enzymes.


Assuntos
Envelhecimento/metabolismo , Antipirina/metabolismo , Ingestão de Energia , Teofilina/metabolismo , Animais , Antipirina/farmacocinética , Antipirina/urina , Sistema Enzimático do Citocromo P-450/metabolismo , Feminino , Ratos , Teofilina/farmacocinética , Teofilina/urina
17.
Chirality ; 7(8): 626-31, 1995.
Artigo em Inglês | MEDLINE | ID: mdl-8593256

RESUMO

Conscious male Wistar SPF Riv:TOX rats were dosed intravenously with 2.5, 5, or 10 mg/kg rac-propranolol.HCl, or with 5 mg/kg of either (-)-(S)- or (+)-(R)-propranolol.HCl. Disposition of (-)-(S)- and (+)-(R)-propranolol after dosing of rac-propranolol was linear in the dose range examined. Total plasma clearance was not changed in animals dosed with the individual enantiomers compared to the animals that were dosed with rac-propranolol. However, for (-)-(S)-propranolol both volume of distribution and elimination half-life decreased, whereas for (+)-(R)-propranolol increases were observed for these characteristics, in animals dosed with the individual enantiomers. Our observations suggest that the (+)-(R)-enantiomer competes with (-)-(S)-propranolol for plasma protein binding sites, resulting in lower plasma protein binding of the (-)-(S)-enantiomer when the racemate is administered. From recent toxicological experiments, it was concluded that rac-propranolol is more toxic than the individual enantiomers in the rat, when dosed iv at the same total mass. It is concluded that the observed potentiation of toxic effects of propranolol enantiomers when administered as a racemate can at least partly be explained by a pharmacokinetic interaction.


Assuntos
Antagonistas Adrenérgicos beta/farmacocinética , Antagonistas Adrenérgicos beta/toxicidade , Propranolol/farmacocinética , Propranolol/toxicidade , Antagonistas Adrenérgicos beta/administração & dosagem , Animais , Proteínas Sanguíneas/metabolismo , Cromatografia Líquida de Alta Pressão , Relação Dose-Resposta a Droga , Meia-Vida , Injeções Intravenosas , Masculino , Propranolol/administração & dosagem , Ligação Proteica , Ratos , Ratos Endogâmicos , Ratos Wistar , Estereoisomerismo
18.
Br J Clin Pharmacol ; 38(2): 125-9, 1994 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-7981012

RESUMO

1. The pharmacokinetics of R(+)-bupivacaine and S(-)-bupivacaine were investigated following a 10 min intravenous infusion of the racemate (dose 30 mg) in 10 healthy males. 2. The fractions unbound of R(+)- and S(-)-bupivacaine in pre-dose plasma were determined for each subject after in vitro addition of rac-bupivacaine (concentration of each enantiomer: approximately 300 ng ml-1). 3. The total plasma clearance of R(+)-bupivacaine (mean +/- s.d.: 0.395 +/- 0.076 l min-1) was greater (P < 0.0001) than that of S(-)-bupivacaine (0.317 +/- 0.067 l min-1). The volumes of distribution of R(+)-bupivacaine at steady state (84 +/- 29 l) and during the terminal log-linear phase (117 +/- 47 l) were larger (P < 0.0002) than those of S(-)-bupivacaine (54 +/- 20 l and 71 +/- 34 l, respectively). The terminal half-life (210 +/- 95 min) and mean residence time (215 +/- 74 min) of R(+)-bupivacaine were longer than those of S(-)-bupivacaine (157 +/- 77 min, P < 0.01, and 172 +/- 55 min, P < 0.02, respectively). 4. The free percentage of R(+)-bupivacaine (6.6 +/- 3.0 %) was greater (P < 0.0002) than that of S(-)-bupivacaine (4.5 +/- 2.1 %). 5. The plasma clearance of unbound R(+)-bupivacaine (7.26 +/- 3.60 1 min-1) was smaller (P < 0.01) than that of S(-)-bupivacaine (8.71 +/- 4.27 l min-1). Volumes of distribution based on unbound R(+)-bupivacaine concentrations (Vuss: 1576 +/- 934 l; Vu: 2233 +/- 1442 l) did not differ from those of S(-)-bupivacaine (Vuss: 1498 +/- 892 l; Vu: 1978 +/- 1302 l). 6. The enantioselective systemic disposition of bupivacaine can to a large extent be attributed to differences in the degree of plasma binding of the enantiomers.


Assuntos
Bupivacaína/farmacocinética , Adulto , Análise de Variância , Proteínas Sanguíneas/metabolismo , Coleta de Amostras Sanguíneas , Bupivacaína/administração & dosagem , Bupivacaína/sangue , Bupivacaína/química , Humanos , Infusões Intravenosas , Masculino , Ligação Proteica , Estereoisomerismo
19.
J Chromatogr B Biomed Appl ; 655(1): 163-6, 1994 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-8061827

RESUMO

A clean-up procedure to obtain a minimal detectable concentration of 5-10 ng bupivacaine enantiomer per milliliter human plasma is described. The procedure consists of precipitation of plasma proteins using acetonitrile, followed by solid-phase extraction using a cyano column. The eluate is then made alkaline, and bupivacaine is extracted using n-hexane. After evaporation of n-hexane, the residue is redissolved in the eluent used for HPLC analysis. The HPLC method has been described previously. The minimal detectable concentrations using this method are ca. 8 and 10 ng/ml for R-(+)- and S-(-)-bupivacaine, respectively. For both enantiomers, r2 is > 0.995 over the range of 9.5-760 ng/ml enantiomer.


Assuntos
Bupivacaína/sangue , Cromatografia Líquida de Alta Pressão , Humanos , Injeções Intravenosas , Estereoisomerismo , Ultrafiltração
20.
Environ Health Perspect ; 102(2): 182-4, 1994 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-8033848

RESUMO

In some parts of The Netherlands, bog ore-containing soils predominate, which have natural arsenic levels that exceed, by a factor of 10, existing standards for maximum allowable levels of inorganic arsenic in soil. These standards are based on the assumption that in humans the bioavailability of arsenic from ingested soil is equal to that from an aqueous solution. In view of the regulatory problem that the arsenic levels of these soils present, we questioned the validity of this assumption. To obtain a more realistic estimate, the bioavailability of inorganic arsenic from soil in a suitable animal model was studied. In this report, a study performed in six dogs in a two-way cross-over design is presented. The dogs received orally, in random order, arsenic both as an intravenous solution and as arsenic-containing soil. During a 120-hr period after administration urine was collected in 24-hr fractions. Levels of arsenic were determined using a method of wet digestion, isolation and complexation of arsine, followed by molecule absorption spectrometry. Within 120 hr after intravenous administration, 88 +/- 16% of the dose was excreted renally. After oral administration of arsenic-containing soil, only 7.0 +/- 1.5% was excreted renally. From the urinary excretion data for these two routes of administration, the calculated bioavailability of inorganic arsenic from soil was 8.3 +/- 2.0%. The results from this study demonstrate the need to reconsider the present risk assessment for arsenic in soil.


Assuntos
Arsênio/farmacocinética , Poluentes do Solo/farmacocinética , Animais , Disponibilidade Biológica , Cães , Feminino , Masculino , Fatores de Risco
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