ISSN:0312-5963    

出版商:ADIS    

年代:1990

数据来源: ADIS

摘要:

The &bgr;-agonists have found wide clinical use as racemic mixtures for 20 years, but information on their pharmacokinetics is not comprehensive. They are well absorbed orally, but have low systemic availability due to extensive first-pass sulphation. When administered by inhalation, very little of the administered dose reaches the lungs, but the small amount that does produces effective bronchodilatation. Plasma protein binding of most &bgr;-agonists is negligible, and there is substantial extravascular distribution of the administered dose. Elimination of intravenous drug is predominantly renal, whereas oral doses are mostly eliminated by biotransformation. Renal clearance correlates with creatinine clearance; therefore, dose reduction should be considered if renal function is impaired, such as in the elderly or in cardiac failure. The elimination half-life of most &bgr;-agonists is relatively short, and pharmacokinetics are independent of dose and duration of treatment. Differences in the pharmacokinetics of the enantiomers are evident.There is very large variation in pharmacodynamic response for a given plasma &bgr;2-agonist concentration among different subjects, and as treatment proceeds in an individual subject. Therefore, in most cases therapeutic response and side effects are more useful for the monitoring of &bgr;2-agonist treatment than measurement of plasma drug concentrations.The pharmacokinetics of &bgr;2-agonists are not greatly altered in pregnancy although these agents cause a marked reduction in maternal renal function. Placental transfer is relatively rapid, and side effects are observed in fetus and neonate. Elimination may be somewhat faster in children (8 to 15 years) than in young adults. Asthma does not appear to influence the pharmacokinetics of &bgr;2-agonists; the only recorded drug interaction of clinical significance is an increase in theophylline clearance by intravenous isoprenaline (isoproterenol). Controlled release oral preparations do not reduce side effects, but may improve compliance due to less frequent dosing.The application of pharmacokinetic principles may improve the clinical usage of &bgr;-agonists, at least when they are used in premature labour and in cardiac failure.

ISSN:0312-5963    

出版商:ADIS    

年代:1990

数据来源: ADIS

摘要:

Antihypertensive treatment has proven benefits, and the number of patients being treated with these drugs is significant. Hypertensive patients may have other medical illnesses for which they receive medications, and interactions between antihypertensive agents and other drugs is likely. Some of these interactions may lead to undesirable effects or even loss of blood pressure control. However, drug interactions can also be beneficial when 2 antihypertensive drugs with different pharmacological actions are prescribed in combination and with a clear therapeutic objective in mind. Clinicians should be aware of the mechanisms and the consequences of the different types of interaction in hypertensive patients, so that a desired pharmacological response can be achieved with the fewest side effects in the patients.

ISSN:0312-5963    

出版商:ADIS    

年代:1990

数据来源: ADIS

摘要:

There is considerable interindividual variation in the relationship between control of seizures and the serum anticonvulsant concentration. The minimum effective serum concentration is dependent on the type and severity of the epilepsy, and varies from patient to patient. The therapeutic range should be used as a guide to adjust the dose in order to further improve seizure control or reduce toxicity; the latter is more likely with higher serum concentrations, but can also be present when concentrations are low. A request for the serum concentration of an anticonvulsant should be made only for good clinical reasons, and an interpretation of that concentration can only be made if all the relevant clinical details are available.Indications for the measurement of serum anticonvulsant concentrations include poor seizure control, toxicity, suspected gross noncompliance, status epilepticus and the elapse of 2 to 4 weeks after the initiation of therapy. Additional drug therapy, pregnancy or illness may alter drug disposition in a well controlled patient and therapeutic drug monitoring may, therefore, help to prevent seizures secondary to these changes. The measurement of anticonvulsants in saliva as opposed to serum may be of benefit in some patients.

ISSN:0312-5963    

出版商:ADIS    

年代:1990

数据来源: ADIS

摘要:

The pharmacokinetics of chlorpromazine after intravenous infusion were studied in 25 children.The pharmacokinetic parameters studied are markedly different from those reported for adults. A clear relationship was demonstrated between age, serum terminal half-life (r = 0.75) and systemic clearance (r = −0.43). It appears that the pharmacokinetics of chlorpromazine are more rapid in children than in adults.

ISSN:0312-5963    

出版商:ADIS    

年代:1990

数据来源: ADIS

摘要:

Oxiracetam, a nootropic drug, could be of potential use in the treatment of memory disturbances in patients with epilepsy who are using antiepileptic drugs. The half-life of oxiracetam appears to be influenced by the concomitant use of carbamazepine or valproic acid, necessitating more frequent administration of oxiracetam than is recommended for other conditions. No effect was observed on the serum concentrations of these antiepileptic drugs by oxiracetam. Long term concurrent use of oxiracetam and antiepileptic agents does not appear to be contraindicated.

ISSN:0312-5963    

出版商:ADIS    

年代:1990

数据来源: ADIS