摘要:

Therapeutic drug monitoring is now widely used in many areas of medicine. With its proliferation has come an understanding of the clinical situations in which it is likely to be of value. Factors that can limit the usefulness of therapeutic drug monitoring and situations where it is less likely to be of benefit have also been identified.At present, the routine use of therapeutic drug monitoring in antineoplastic therapy is limited to measurement of plasma methotrexate concentrations after high-dose methotrexate therapy. The lack of a more widespread application of therapeutic drug monitoring in oncology has been due to deficiencies in knowledge about the clinical pharmacology of antineoplastic agents and to factors specific to the chemotherapy of neoplasms. These factors include the broad heterogeneity of malignant neoplasms, the complexities of the drug-tumour interaction, difficulties in assessment of this interaction and the use of combinations of antineoplastic agents with cumulative efficacies and toxicities.Despite these problems, there are many areas in antineoplastic therapy where the use of therapeutic drug monitoring could prove of benefit. The prevention of the chronic pulmonary toxicity of bleomycin, the assessment of the bioavailability of oral chemotherapy, and monitoring drug disposition in the presence of hepatic or renal dysfunction are just some of the potential applications.If recent emphasis on dose as a critical factor in the success of cancer chemotherapy is substantiated, then the need to apply therapeutic drug monitoring within oncology will become more pressing.

ISSN:0312-5963    

出版商:ADIS    

年代:1987

数据来源: ADIS

摘要:

Antibiotics are administered to cystic fibrosis patients for chronic endobronchial infection complicated by frequent exacerbations. Agents active againstStaphylococcus aureus, Pseudomonas aeruginosaor both are administered. Serum antibiotic concentrations were measured in cystic fibrosis patients in an effort to optimise antibiotic dose and frequency. This led to the observation that cystic fibrosis subjects had (in general) a larger Vd and increased total body clearance of &bgr;-lactams and aminoglycosides than non-cystic fibrosis subjects. The larger Vd is mainly due to the increased amount of lean body mass per kg bodyweight, although increased tissue binding may also account for part of this. The increased total body clearance of &bgr;-lactams appears to be due to increased renal elimination, particularly tubular secretion. Decreased tubular reabsorption and increased non-renal clearance contribute to the increased total body clearance of metabolised &bgr;-lactams and aminoglycosides. However, the lack of concomitant controls in many studies make these generalisations tentative.The result of the apparent cystic fibrosis-specific differences is lower peak serum antibiotic concentrations, a smaller AUC, and a shorter elimination half-life than non-cystic fibrosis subjects. Since sputum (and bronchial mucosal) concentration is dependent on the peak serum concentration (and AUC), cystic fibrosis subjects require larger doses of most antibiotics more frequently. Newer quinolones may be an exception. Studies comparing the efficacy and safety of larger and more frequent antibiotic doses to conventional therapy are not available. Although it appears logical to mimic serum antibiotic concentrations found in non-cystic fibrosis subjects, the lack of information on the ideal sputum concentrationversustime curve should temper our enthusiasm for cystic fibrosis-specific dosage regimens.

ISSN:0312-5963    

出版商:ADIS    

年代:1987

数据来源: ADIS

摘要:

Several new diuretics have recently been developed. This review summarises the published knowledge about some of them.Azosemide is a loop diuretic. The bioavailability is about 15% and it has a half-life of 2 to 3 hours. Renal and non-renal clearance are 1.32 and 5.4 L/h, respectively. Etozolin is also a loop diuretic. It is rapidly metabolised to the active metabolite, ozolinone. The gastrointestinal uptake of etozolin is almost complete. The plasma half-life of etozolin and ozolinone are 2 and 10 hours, respectively. The compounds are mainly eliminated as metabolites. Renal and liver impairment do not seem to change the pharmacokinetics. Fenquizone has properties similar to the thiazides. The plasma half-life is approximately 17 hours. Apparent volume of distribution averaged 686L and renal clearance is 7.2 L/h.Indapamide acts predominantly on the proximal segment of the distal tubule and also has direct vasodilatory effects. Gastrointestinal uptake is at least 80%. The drug binds highly to carbonic anhydrases of red blood cells. Protein binding is about 80%, while terminal plasma half-life is 15 hours and the apparent volume of distribution 25L. Renal clearance is 0.3 L/h and non-renal clearance 0.9 L/h. Several metabolites have been described, of which one major metabolite is pharmacologically active.Muzolimine is a loop diuretic. Its uptake is almost complete, but decreased substantially by food. The protein binding is about 65%, the apparent volume of distribution is about 1 L/kg and average terminal half-life 10 to 20 hours. Elimination is mainly non-renal, and non-renal clearance ranges between 0.5 and 1.32 L/h. The pharmacokinetics of the drug do not seem to be changed in cardiac failure. Terminal plasma half-life is essentially unchanged in patients with renal failure, except in those with very severe reduction of glomerular filtration rate.Piretanide is a loop diuretic which is about 6 times as potent as frusemide (furosemide). Its bioavailability is most likely complete in healthy subjects and in renal patients. Protein binding in healthy subjects is about 95%. The plasma half-life of the drug is about 1 hour and apparent volume of distribution averages about 17L. Renal and non-renal clearance are about 6 L/h, although renal clearance is decreased in renal failure: this decrease is correlated with glomerular filtration rate. Non-renal clearance is unchanged in renal failure, as is the apparent volume of distribution. The overall sensitivity of the kidneys to piretanide is normal in renal patients, but sensitivity at the nephron is severely reduced, as a much higher excretion rate of piretanide per nephron in renal failure is necessary for a certain response.Torasemide is a loop diuretic which, in addition to interfering with Na-2Cl-K carrier, also blocks the chloride channels. Bioavailability is about 90%, while the half-life of the terminal plasma phase ranges from 2 to 3 hours. The apparent volume of distribution is about 11L and the total clearance of the diuretic averages about 3.6 L/h, 25% of which is accounted for by renal clearance.Xipamide has diuretic properties similar to those of the thiazides, with a bioavailability of about 80%. The drug is highly protein bound (99%). Plasma half-life is about 7 hours and apparent volume of distribution 21L. Renal and non-renal clearance approximate 0.72 and 1.38 L/h, respectively. Elimination rate is lower in patients with renal failure.

ISSN:0312-5963    

出版商:ADIS    

年代:1987

数据来源: ADIS

摘要:

Food-induced changes in the absorption of Theostat 300®, a controlled release formulation of theophylline, have been studied in healthy volunteers. This open, randomised, 3-way, single-dose study involved 12 volunteers who received the drug either while fasting, or with a standardised low-fat (10g), or high-fat (60g) breakfast. Each subject was studied over a 3-week period, with 3 separate days of oral treatment and a 7-day washout period between treatments.The results showed no differences in AUC0-24and tmaxvalues between the 3 kinds of diet. The only differences observed concerned absorption. Food intake increased Cmaxvalues by 20%. The steady-state peak concentration obtained by means of simulated plasma levels was not influenced by food intake. This slight food-drug interaction of Theostat 300® seemed to be of no clinical significance.

ISSN:0312-5963    

出版商:ADIS    

年代:1987

数据来源: ADIS