RESUMO
In vitro binding of amantadine to plasma protein was assessed by ultrafiltration of plasma samples (from a blood bank) to which amantadine hydrochloride had been added. Approximately two-thirds of the amantadine was found to be protein-bound. The degree of protein binding was constant over a plasma amantadine concentration range of 100-2,000 ng/ml.
Assuntos
Amantadina/metabolismo , Proteínas Sanguíneas/metabolismo , Humanos , Técnicas In Vitro , Ligação Proteica , Albumina Sérica/metabolismo , UltrafiltraçãoRESUMO
To study the disposition of amantadine hydrochloride in patients with impaired renal function, 100 mg was administered orally to 13 patients with creatinine clearances ranging from 48 to 10 ml/min/1.73 m2 body surface area. Six adults with normal renal function served as controls. Plasma half-life averaged 68.5 +/- 9.5 SEM hours in the renal patients (range: 27 to 144), versus 12.6 +/- 1.7 hours in controls. Plasma half-life correlated significantly with serum creatinine (r = 0.8476, P less than 0.001) and serum urea nitrogen levels (r = 0.8791, P less than o.001). Similarly, plasma elimination constant correlated with creatinine clearance/1.73 m2 body surface area (r = 09201, P less than 0.001). Renal amantadine clearance also correlated with creatinine clearance/1.73 m2 body surface area (r = 0.8217, P less than 0.001). However, renal amantadine clearance regularly exceeded creatinine clearance, suggesting that tubular secretion plays a role in the elimination of this drug. Amantadine excretion is decreased in patients with impaired renal function. The amount by which dosage must be reduced can be estimated based on creatinine clearance.
Assuntos
Amantadina/uso terapêutico , Falência Renal Crônica/complicações , Infecções Respiratórias/tratamento farmacológico , Adulto , Amantadina/metabolismo , Antivirais/metabolismo , Antivirais/uso terapêutico , Ensaios Clínicos como Assunto , Creatinina/sangue , Creatinina/urina , Avaliação de Medicamentos , Humanos , Falência Renal Crônica/metabolismo , Masculino , Diálise Renal , Infecções Respiratórias/complicações , Infecções Respiratórias/metabolismoRESUMO
To study the fate of amantadine hydrochloride in patients with renal failure, we gave 100 mg orally to 12 such patients immediately after hemodialysis. Plasma levels did not decrease between 24 and 44 hours after drug ingestion, suggesting an extremely poor total body clearance. Apparent volume of distribution was 5.1 +/- 0.2 (SEM) L/kg of body weight. Between 44 and 48 hours, as a result of 4 hours of hemodialysis, the mean plasma drug level decreased from 268 to 225 ng/mL (P less than 0.001). Dialyzer clearance was 67.0 +/- 3.9 mL of plasma per minute. The total quantity of drug removed by the dialysis treatment, however, was only 3.9 +/- 0.25 mg. The average half-life of amantadine in eight patients studied while receiving maintenance hemodialysis was 24.3 +/- 2.4 h of dialysis administered over approximately 13 days. Plasma half-life in six nonuremic control subjects was 12.2 +/- 1.6 h. Amantadine is poorly excreted in dialysis patients and has a large volume of distribution. The amount removed by a single dialysis is only a small fraction of the total body store.
