The administration of 5-fluorouracil by mouth

Oral 5-fluorouracil in squamous cell carcinoma of the skin in the aged

Multiple or recurrent squamous cell skin carcinoma is a rare tumor in the aged. These patients are currently treated with 5-fluorouracil (5-FU) cream as a local chemotherapy; in cases in which the disease progresses, few treatments are available. Two reports deal with the treatment of progressive squamous cell skin carcinoma with systemic 5-FU, but in only eight patients age less than 70 years. We prospectively investigated oral 5-FU therapy in 14 consecutive patients (average age 76 1/2 years) with histologically proven squamous cell skin carcinoma. The disease was aggressive, multiple, or recurrent and had not been eradicated by surgery, radiation therapy, topical 5-FU cream, and non-5-FU chemotherapy. Oral 5-FU was administered as mannitol-coated 5-FU tablets at the daily dose of 175 mg/m2 for 3 weeks every 5 weeks. Toxicity, effectiveness, quality of life, and compliance to therapy were evaluated. Total cycles amounted to 55 (range: 2-6, mean: 4 for each patient) at an average dose intensity of 740 mg/m2/week for from 12 to 36 weeks. Only gastrointestinal toxicity World Health grade I occurred. Quality of life and compliance to therapy were 90%. Therapy induced measurable improvement in nine patients (64.3%): two partial remissions (14.3%), three minimal remissions (21.4%), and four arrests of disease (28.6%) with a median duration of 30+ months. The study ended because of a lack of patients. We can conclude that, if elderly patients require chemotherapy because of progressive multiple or advanced squamous cell skin carcinoma, appreciable results may be obtained with oral 5-FU as a single agent.

Regional chemotherapy of liver metastases from colorectal carcinoma: hepatic artery or portal vein infusion?

Hepatic artery infusion (HAI) chemotherapy has been well developed and is commonly used in the treatment of unresectable hepatic colorectal metastases. However, several important questions are unanswered, such as survival advantage over conventional systemic intravenous chemotherapy, long-term effects on the liver function, and prevention of complications, in particular cholangiosclerosis. Recent investigation into the blood supply of liver tumors challenges the adage that arterial flow is dominant. This review of the merits of regional HAI compared with portal venous infusion (PVI) chemotherapy shows a lack of conclusive data to favor either treatment modality, although a larger experience exists for HAI. Further studies need to be conducted.

Adjuvant chemotherapy of gastric carcinoma: a pilot study of oral administration of injectable 5-fluorouracil

During the past three years we have entered 54 patients with gastric adenocarcinoma into a clinical trial of oral administration of injectable 5-fluorouracil (5-Fu). Of the 20 unresectable advanced cases, the median survival was 6.2 months, and for 34 resectable ones, median survival was 22 months. These results were comparable to those reported in the literature. It is also safe, easy to administer, well tolerated, and does not have any apparent side effects. The author discovered for the first time that oral administration of 5-Fu could improve the liver function as manifested by a marked decrease of serum GPT level in advanced gastric cancer.

5-Fluorouracil: a comparative pharmacokinetic study and preliminary results of a clinical phase I study

Until now it was unknown, whether 5-fluorouracil (5-FU) would be absorbed sufficiently after oral application, so that therapeutical effects could be expected. For this reason a comparative pharmacokinetic study of intravenous versus oral application was performed on six patients, as well as a pilot study on 13 patients with adenocarcinomas of different origins. The results show that 5-FU is absorbed rapidly. The biological availability increases with higher dose, which would indicate a saturation of the "first pass" in the liver. The clinical study shows partial remission in seven patients, with hepatoma and tolerable signs of bone marrow depression, decrease of hemoglobin, leukocytes and platelets after oral application of 5-FU in doses of 1,000-1,250 mg on days 1, 3, 5, 8, 10, and 12. 5-FU can therefore be given successfully at an adequate dose by the oral route.

Pharmacokinetic studies of 5-fluorouracil after oral and intravenous administration in man

The pharmacokinetic conditions for oral administration of 5-fluorouracil (5-FU) were investigated in 16 patients with malignant liver tumours. The concentration of 5-FU in portal and systemic blood was determined by a microbiologic method every 10 min. during 2 hours after oral or intravenous administration of a standard dose of 250 mg 5-FU ( approximately 4 mg/kg b. wt.) or 15 mg 5-FU/kg b. wt. The drug was rapidly absorbed after oral administration with peak values within 10-30 min. 25% of the lower and 40% of the higher oral dose reached the systemic circulation. The reduction of systemic bio-availability was partly accomplished by a loss in the gastrointestinal tract and partly by extraction by the liver. The hepatic extraction ratio was calculated to 0.56 and 0.26 after the lower and the higher dose respectively indicating a saturable process. The availability of 5-FU was significantly higher in portal blood than in systemic blood after oral administration. The opposite conditions were found after intravenous administration. Thus, oral administration of 5-FU to patients with malignant liver tumours seems rational.

Regional and systemic serum concentrations of 5-fluorouracil after portal and intravenous infusion: an experimental study in dogs

The serum and urinary concentrations of 5-FU after continuous portal and jugular infusion have been followed by means of a highly sensitive microbiological assay method. Our data indicate that more than 90% of 5-FU was eliminated in the liver after continuous portal infusion of 0.625 mg x kg-1 x hr-1, corresponding to a dose of 15 mg x kg-1 x 24 hr-1. Negligible amounts of intact 5-FU were excreted into the bile, and the urinary excretion was only a few percent of the amount infused. The arterial concentration was on average tenfold higher during the continuous jugular infusion than after the continuous portal infusion, indicating that the route of administration has a pronounced effect on the disposition of 5-FU. Twenty-three percent of the jugular dose reached the liver; 77% was degraded by extrahepatic metabolism. Of these, degradation in the prehepatic splanchnic area accounted for 15%.

Plasma levels of 5-fluorouracil after oral and intravenous administration in cancer patients

1. Plasma levels of 5-fluorouracil (5FU) have been determined in eleven cancer patients after 0.5 g and 1.0 g intravenous doses, and in one patient after paired 1.0 g oral and intravenous doses. 2. The plasma half-life after the 0.5 g intravenous dose was relatively constant, irrespective of the stage and spread of the disease. 3. Plasma kinetics of the drug were dose dependent. Doubling of the intravenous dose produced a 1.5-fold increase in plasma half life, a two-fold increase in initial plasma drug concentration, and a three-fold increase in area under the concentration/time curve. 4. In one patient receiving paired 1.0 g intravenous and oral doses nine weeks apart, an increase in the bioavailability of the drug coincided with a marked clinical regression in palpable intra-abdominal metastases. 5. The significance of measuring plasma drug kinetics and their relationship to drug efficacy and toxicity are discussed.

Cytotoxic drugs and the human adrenal cortex: a cell culture study

Primary monolayer cultures of nonproliferating adult human adrenocortical cells have been used to screen 18 cytotoxic drugs used in cancer chemotherapy for direct effects on corticosteroidogenesis. None of the drugs tested, with the exception of 5-fluorouracil (5-FU) and its metabolite 5-fluorodeoxyuridine, showed significant activity at levels compatible with cortical cell viability and/or likely to be encountered during therapy. These two antimetabolites, however, resulted in a slow but long-lived reversible suppression of corticosteroidogenesis in both ACTH- and monobutyryl cyclic AMP-stimulated, as well as unstimulated cultures of human cells. Thus 10 micrograms/ml resulted in less than 80% inhibition after seven days treatment without any evidence of overt cytotoxicity. High-pressure liquid chromatography showed a suppression of all UV-absorbing steroids secreted. Examination of the ultrastructure of the treated cells showed significant changes in mitochondrial morphology, suggesting a possible site of action for the antisteroidogenic effects of 5-fluorouracil. These in vitro results suggest the possibility of adrenal suppression in vivo during long-term or high dose infusion 5-FU chemotherapy.

Fluorouracil therapy in patients with carcinoma of the large bowel: a pharmacokinetic comparison of various rates and routes of administration

The pharmacokinetics of fluorouracil after oral, intravenous and rectal administration were compared in 12 patients with colorectal cancers. Oral administration of 10 to 15 mg/kg gave variable plasma levels (0 to 10.5 microgram/ml) and bioavailability (0 to 74%; mean 28%). Bioavailability increased markedly with increases in dose, suggesting saturation of the 'first pass' hepatic metabolism of the drug. Differences in bioavailability could not be related to standard liver function tests or the presence of metastatic deposits in the liver. Plasma levels were not detectable after rectal administration in the 4 patients studied and were very low (0 to 8 microgram/ml) during high dose (20 to 30 mg/kg/24h) slow intravenous infusion in 6 patients. These findings indicate that different dose schedules and routes of administration produce markedly different plasma levels. They suggest that the rate of degradation of fluorouracil by the liver is quite variable and may become saturated with increasing dose. For these reasons monitoring of plasma levels of the drug in individual patients may be useful.

Pharmacokinetics of 5-fluorouracil: inter-relationship with biochemical kinetics in monitoring therapy

The major difficulty in using pharmacokinetic concepts for monitoring individual therapy with 5-fluorouracil is based on the mostly intracellular location of the active nucleotide metabolites of 5-fluorouracil with no clear correlation of plasma levels of the drug. In addition, the basic biochemical mechanism of 'thymine-less cell death' following inhibition of de novo thymidylate synthesis by 2'-deoxy-5-flurouridine 5'-monophosphate (FdUMP) is poorly understood, and only some of the biochemical determinants of therapeutic response to 5-fluorouracil are known. Individualised therapy with 5-fluorouracil requires an intergrated approach which should include methods of pharmacokinetics and biochemical kinetics. 5-Fluorouracil stands as an example for most of the pyrimidine and purine metabolites to which similar consideration apply in monitoring of cancer chemotherapy.

Intraluminal, lymph node, hepatic, and serum levels after intraluminal and intramural injection of 5-fluorouracil in the dog colon

The tissue levels of 2-14C 5-fluorouracil were compared after three routes of administration in the colon of fifteen dogs. "Simple" submucosal injection resulted in higher levels in the colonic wall, abdominal lymph nodes, and liver than did rapid intravenous injection. Intraluminal administration demonstrated that the appearance of 5-FU was prompt and that significantly higher levels continued in the colonic wall and liver, but nodal levels were markedly lower.