Phase I and pharmacokinetic study of oral UFT, a combination of the 5-fluorouracil prodrug tegafur and uracil

UFT is an oral preparation combining the 5-fluorouracil (FU) prodrug tegafur (FT) and uracil (U) in a 1:4 ratio, which is commercially available in Japan for the treatment of breast and gastrointestinal cancers. We sought to determine the tolerance of daily oral UFT and to relate this tolerance to the pharmacokinetics of FT and/or the derived FU, while exploring the possibility of circadian FU kinetics contributing to the results. A 28-day schedule followed by 2 weeks rest was began at the initial level of 300 mg/m2/day administered either at 8 a.m. or at 6 p.m. At the following level, 400 mg/m2/day patients were randomly assigned to a split-dose administration or to the above single, timed dose administration. Intolerance to single dosing was clearly demonstrated, and only the split dosing was advanced to 500 mg/m2/day. When this level proved too toxic, 400 mg/m2 was studied further on a 7 a.m., 3 p.m., and 11 p.m. (every 8 h) schedule. Pharmacology was determined on selected patients. In the single dose administration, areas under the curves of FU were higher following p.m. dosing, although substantial interpatient variation was present. Toxicities (diarrhea and neutropenia) were more severe in patients receiving the drug in single daily doses. We conclude that the kinetics of FT are saturable, with disproportionate increases in area under the curve (and toxicities) as dose levels are increased. With divided dosing, tolerance improves. UFT at a dose of 400 mg/m2/day administered as three divided doses (every 8 h) is suitable for Phase II studies, although toxicity requiring cessation of drug administration prior to completion of 28-day cycles will occur in some patients.     

Comparison of 5-fluorouracil pharmacokinetics in patients receiving continuous 5-fluorouracil infusion and oral uracil plus N1-(2''-tetrahydrofuryl)-5-fluorouracil

In order to examine the relationship between long-term potentiation (LTP) and phosphoinositide (PI) turnover, we evaluated these throughout anesthetized rat brain using carbon-11-labeled diacylglycerol (11C-DAG). High-frequency tetanic stimulation (400 pulses at 400 Hz) to the perforant pathway induced LTP in rat dentate gyrus. In autoradiograms of rat brains, LTP was associated with the occurrence of multiple highly radioactive spots in many regions distant from the stimulated site. Following i.v. administration of an NMDA receptor antagonist prior to stimulation, however, no high-density spots were found. These findings directly demonstrate that potentiation of phosphoinositide-derived signaling was induced during LTP, and the finding of multiple location suggests the occurrence of polysynaptic neurotransmission through neural networks pertaining to learning and memory.     

Anticancer activity and toxicity of S-1, an oral combination of tegafur and two biochemical modulators, compared with continuous i.v. infusion of 5-fluorouracil

S-1 is an oral combined form of 1 M tegafur [a prodrug of 5-fluorouracil (5-FU)], 0.4 M 5-chloro-2,4-dihydroxypyridine (a reversible inhibitor of dihydropyrimidine dehydrogenase) and 1 M potassium oxonate (an inhibitor of orotate phosphoribosyltransferase). S-1 has been shown to exert a potent antitumor effect with low gastrointestinal toxicity in experimental tumor models. We have therefore compared the antitumor effect of oral S-1 with that of continuous infusion of 5-FU in rats bearing transplants of human and murine tumors. Almost complete inhibition of the tumor growth was obtained on 7 day schedules in Yoshida sarcoma-bearing rats by consecutive administration of 30 mg/kg/day of oral S-1 and 40 mg/kg/day infusion of 5-FU. However, a significant difference between the incidence of toxicities of S-1 and 5-FU, including body weight loss and diarrhea, was noted. The rats given the 5-FU infusion had marked weight loss and severe diarrhea, while those given oral S-1 had neither. Although about 50% inhibition of the tumor growth was attained with 15 mg/kg/day of oral S-1 and 30 mg/kg/day infusion of 5-FU in nude rats with xenografted human colon cancer (KM12C), the rate of body weight loss in the 5-FU-treated group was distinctly higher than in the S-1-treated group. The ratio of the 5-fluoronucleotide concentrations in gastrointestinal tissue to that in the tumor was lower in the S-1-treated rats than in the 5-FU-treated rats. In conclusion, the results suggest that oral S-1 might be more effective in the treatment of cancer patients than continuous infusion of 5-FU, from the standpoint of antitumor potency and toxicity.     

Observations on the efficacy and pharmacokinetics of sotalol after oral administration

The effects of sotalol after oral administration were measured on the tachycardia induced by strenuous exercise in normal subjects. Plasma sotalol levels were also determined. The oral administration of sotalol (50, 100, 200 and 400 mg) to 6 subjects produced a progressive reduction in the tachycardia induced by severe exercise. This was similar to the effects of 25, 50, 100, 200, 400 and 800 mg given to different subjects. Each increase in sotalol dose produced a successively greater reduction in exercise tachycardia. This did not appear to be maximum even with 800 mg. Oral sotalol was rapidly absorbed and produced peak blood levels in 2 - 3 hours. The plasma levels of sotalol measured 2 hours after the oral administration of 25 to 800 mg showed never more than a six-fold variation between different subject. The half-life of sotalol in plasma was 12.7 +/- SE 1.6 hours. There was a significant correlation between the logarithm of the plasma sotalol concentration and the percentage reduction of exercise heart rate. It is concluded that the oral administration of sotalol either once or twice daily (depending on dose level) will provide satisfactory 24-hour blockade of beta-adrenoceptors.     

Postsurgical oral administration of uracil and tegafur inhibits progression of micrometastasis of human breast cancer cells in nude mice

We recently established a metastasis model in nude mice using the MKL-4 cell line, a contransfectant of the MCF-7 human breast cancer cell line with fgf-4 and lacZ in which micrometastases in several organs can be quantitatively observed. First, to develop a new postsurgical metastasis model, we investigated the timing of occurrence of micrometastasis and the influence of tumor removal on the progression of micrometastasis in this model. Micrometastases into lymph nodes and lungs were detected 3 weeks after the cell injections. Tumor removal 3 weeks after the injections significantly enhanced the progression of micrometastasis into lymph nodes and bone. Second, to study the effect of a mixed compound, UFT (a molar ratio of uracil:tegafur of 4:1), which has been widely used in the postsurgical adjuvant setting in Japan, 15 or 20 mg/kg UFT were administered p.o. for 4 weeks to tumor-bearing mice or to mice in which transplanted tumors were resected 3 weeks after the injections. Either dose of UFT significantly inhibited the tumor growth as well as the progression of micrometastasis into lymph nodes, lungs, liver, and brain. In addition, enhanced progression of micrometastasis in all explored organs by the tumor removal was significantly inhibited by the administration of either dose of UFT. In conclusion, this new postsurgical metastasis model may be useful for evaluating the efficacy of agents used in the postoperative adjuvant setting. UFT may be an effective drug for inhibiting the progression of micrometastasis after surgery.     

Treatment of advanced gastric cancer with oral etoposide, leucovorin and tegafur: experience with an oral modification of the etoposide, leucovorin and 5-fluorouracil (ELF) regimen

Recent data have suggested enhanced therapeutic activity with prolonged administration of both etoposide as well as fluoropyrimidines in the treatment of gastrointestinal malignancies. Based on this rationale, we investigated the clinical effectiveness and tolerance of an oral modification of the widely applied etoposide, leucovorin and 5-fluorouracil (ELF) regimen in patients with advanced gastric cancer. 32 patients with advanced gastric cancer were treated with oral etoposide (100 mg), leucovorin (3 x 100 mg), and tegafur (3 x 200 mg) over 14-21 days for a maximum of six cycles. Objective response was seen in only 5 patients (16%), stable disease was documented in 7 (22%), while the remaining patients progressed during therapy. The median time to progression was 2.8 months (range 0.7-12 months) and median overall survival was 6 months (range 1-18+ months). Due to grade 3 nausea/emesis, 8 patients discontinued treatment prematurely, while 12 patients experienced anorexia and progressive weight loss. Haematological toxicity was modest, with 4 patients developing asymptomatic grade 3-4 granulocytopenia. We conclude that this oral combination regimen cannot be recommended for the treatment of advanced gastric cancer.     

Zatebradine: pharmacokinetics of a novel heart-rate-lowering agent after intravenous infusion and oral administration to healthy subjects

Although high-frequency low-intensity transcutaneous electric nerve stimulation (TENS) has been extensively used to relieve low back pain, experimental studies of its effectiveness have yielded contradictory findings mainly due to methodological problems in pain evaluation and placebo control. In the present study, separate visual analog scales (VAS) were used to measure the sensory-discriminative and motivational-affective components of low back pain. Forty-two subjects were randomly assigned to 1 of 3 groups: TENS, placebo-TENS, and no treatment (control). In order to measure the short-term effect of TENS, VAS pain ratings were taken before and after each treatment session. Also, to measure long-term effects, patients rated their pain at home every 2 h throughout a 3-day period before and 1 week, 3 months and 6 months after the treatment sessions. In comparing the pain evaluations made immediately before and after each treatment session, TENS and placebo-TENS significantly reduced both the intensity and unpleasantness of chronic low back pain. TENS was significantly more efficient than placebo-TENS in reducing pain intensity but not pain unpleasantness. TENS also produced a significant additive effect over repetitive treatment sessions for pain intensity and relative pain unpleasantness. This additive effect was not found for placebo-TENS. When evaluated at home, pain intensity was significantly reduced more by TENS than placebo-TENS 1 week after the end of treatment, but not 3 months and 6 months later. At home evaluation of pain unpleasantness in the TENS group was never different from the placebo-TENS group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Stereoselective pharmacokinetics of bisoprolol after intravenous and oral administration in beagle dogs

We report 81 of 107 cases of hemolytic uremic syndrome (HUS), admitted between July 1994 and February 1996, following an outbreak of Shigella dysenteriae type 1 dysentery in Kwazulu/Natal. All patients, excluding 1, were black with a mean age of 38 months (range 1-121); 50 (61.7%) were males. The mean duration of dysentery was 11.3 days (range 1-41) and HUS 15 days (range 1-91). Most patients had acute oliguric renal failure (90.1%), 42 (51.6%) required peritoneal dialysis. Complications included encephalopathy 30 (37.0%), convulsions 12 (14.8%) and hemiplegia 2 (2.3%), gastrointestinal perforation 8 (9.9%), protein losing enteropathy 26 (32.1%), toxic megacolon 4 (4.9%), rectal prolapse 5 (6.2%), hepatitis 11 (13.6%), myocarditis 5 (6.2%), congestive cardiac failure 3 (3.7%), cardiomyopathy 3 (3.7%), infective endocarditis 1 (1.2%), septicemia 15 (18.5%), disseminated intravascular coagulation 17 (21%). Leukemoid reactions were found in 74 (91.3%) patients, hyponatremia in 56 (69.1%), and hypoalbuminemia in 67 (82.7%). Stool culture for Shigella dysenteriae type I was positive in only 7 (8.6%) patients; Shiga toxin assays were not performed. Outcome was as follows: recovery 32 (39.5%), impaired renal function 8 (9.9%), chronic renal failure 26 (32.1%), end-stage renal disease 1 (1.2%), and death 14 (17.3%) patients.     

Advantage of post-operative oral administration of UFT (tegafur and uracil) for completely resected p-stage I-IIIa non-small cell lung cancer (NSCLC)

OBJECTIVE: Although adjuvant therapy after surgery for non-small cell lung cancer (NSCLC) has been reported to be ineffective, it has been recently reported in prospective randomised studies conducted by two different groups in Japan that oral administration of a 5-fluorouracil (5-FU) derivative drug, UFT (a combination drug of tegafur and uracil) can improve the post-operative survival [The Study Group of Adjuvant Chemotherapy for Lung Cancer (Chubu, Japan). A randomized trial of postoperative adjuvant chemotherapy in non-small cell lung cancer (the second cooperative study). Eu J Surg Oncol 1995;21:69-77; Wada, H., Hitomi, S., Teramatsu, T, West Japan Study Group for Lung Cancer Surgery. Adjuvant chemotherapy after complete resection in non-small-cell lung cancer. J Clin Oncol 1996;14:1048-1054]. To examine the efficacy of UFT as post-operative adjuvant therapy, a retrospective study was performed. METHODS: A total of 655 consecutive patients who underwent complete tumor resection for pathologic stage I-IIIa, NSCLC at the Department of Thoracic Surgery, Chest Disease Research Institute, Kyoto University between 1976 and 1992 were retrospectively reviewed. As post-operative adjuvant therapy, UFT was administrated to 98 patients (UFT group), and was not administered to the other 557 patients (Control group). RESULTS: The 5-year survival rate of the UFT group was 76.5%, which was significantly better than that of the Control group (5-year survival rate: 58.6%, P = 0.005). Stratified with pathologic stage, the efficacy of UFT was seen in the p-stage I disease (5-year survival rate: 88.6% for the UFT group, 72.0% for the Control group, P = 0.013) and in the p-stage IIIa, pN2 disease (5-year survival rate: 54.3% for the UFT group, 37.5% for the Control group, P = 0.037). Multivariate analysis of the prognostic factors also revealed the efficacy of UFT (P = 0.004, 95% confidence interval of relative risk: 0.325-0.840). Post-operative intravenous chemotherapy or radiation therapy did not prove to be significant factors affecting the prognosis. CONCLUSIONS: Efficacy of oral administration of UFT as post-operative adjuvant therapy for completely resected NSCLC was proposed. To confirm the efficacy, a prospective randomized study for a more homogenous patient group is needed.     

Regional pharmacokinetics of 5-fluorouracil in dogs: role of the liver, gastrointestinal tract, and lungs

The purpose of this study was to determine the presence and extent of pulmonary elimination for 5-fluorouracil (FUra). A secondary aim was to characterize the relative importance of the liver, gastrointestinal tract, splanchnic region, and lungs toward the overall elimination of FUra. A total of 10 mixed-breed male and female dogs were used in these acute studies in which FUra was administered through a cephalic vein. Six dogs were studied at sequentially escalated dose rates of 0.125, 0.250, 0.500, 0.750, and 1.00 micromol/min/kg (8-fold range); four dogs were studied at sequentially escalated dose rates of 0.0625, 0.250, 0.750, 1.50, and 2.00 micromol/min/kg (32-fold range). Each infusion lasted 2 h, at which time steady-state plasma concentrations were obtained (i.e., portal vein, carotid artery, hepatic vein, and pulmonary artery), perfusion rates were measured (hepatic artery, portal vein, and cardiac output), and pharmacokinetic parameters were directly assessed. Pulmonary elimination of FUra was conclusively demonstrated. Although only 17% of the drug was extracted by the lungs at the lowest dose rate, pulmonary clearance (16.0 ml/min/kg) was on the order of splanchnic clearance (13.5 ml/min/kg), or larger. As the dose rate increased, pulmonary clearance was more easily saturated than splanchnic clearance. Thus, it appears that at increasing dose rates, the splanchnic region becomes a more significant pathway, whereas the lungs have a reduced role in the overall elimination of FUra.     

Effect of first-pass metabolism on enantioselective pharmacokinetics after oral administration of (+)-, (-)- and racemic homochlorcyclizine to rats

The enantioselective relationship between the pharmacokinetics and hepatic metabolism of homochlorcyclizine hydrochloride (HCZ) was investigated using rats. There were no significant differences in blood concentrations between the three forms after intravenous administration (5 mg/kg) of (+)-, (-)- and racemic HCZ. On the other hand, there were significant differences in the pharmacokinetics between (-)- and (+)-HCZ and between (-)- and racemic HCZ after oral administration (50 mg/kg) of these three forms. The Cmax and AUC0-infinity of (-)-HCZ were lower than those of (+)-isomer and racemate, and its CLo was clearly higher than the others. The (+)-isomer and racemate showed no significant differences in their pharmacokinetic parameters. At a lower dose (10 mg/kg), however, no enantiomeric differences were found in the pharmacokinetic parameters of (+)- and (-)-HCZ. Also examined was the cytochrome p-450-dependent-oxidative metabolism of (+)-, (-)- and racemic HCZ in vitro using rat liver 9000 x g supernatant fraction. The in vitro metabolism of (-)-HCZ was extremely fast, compared with those of the (+)-isomer and the racemate. The Vmax in vitro showed a good correlation with the CLo in vivo after oral administration (50 mg/kg) of all three forms of HCZ. In vitro study of enantiomeric inhibition of the metabolism showed that (+)-HCZ was a competitive inhibitor of (-)-HCZ metabolism, with a Ki of 6.96 microM. (-)-HCZ was also a competitive inhibitor of (+)-HCZ metabolism, with a Ki of 20.4 microM.(ABSTRACT TRUNCATED AT 250 WORDS)     

Species differences in pharmacokinetics of a hepatoprotective agent, YH439, and its metabolites, M4, M5, and M7, after intravenous and oral administration to rats, rabbits, and dogs

Pharmacokinetic parameters of YH439 and its metabolites, M4, M5, and M7, were compared after iv administration of YH439 to rats (1-10 mg/kg), rabbits (1-10 mg/kg), and dogs (1-20 mg/kg) and oral administration of YH439 to rats (50-500 mg/kg) and dogs (0.5-2 g per whole body weight). After oral administration of YH439 to rats, the F values were 3.67, 1.33, and 0.859% for YH439 oral doses of 100, 300, and 500 mg/kg, respectively. However, the F value increased significantly, 21.2%, after oral administration of YH439-contained mixed micelles (10 mg as free YH439) to rats due to increased water solubility of YH439. Species differences in the pharmacokinetics of YH439 and its metabolites were found. First, M7 was detected in both plasma and urine after both iv and oral administration of YH439 to dogs, whereas it was detected neither in rats nor in rabbits, indicating that considerable amount of M7 was formed from YH439 only in dogs. Second, the AUC (or AUC0-->t) ratios of M4 to YH439 after iv administration of YH439 were 24.6-31.3, 42.2-49.2, and 2200-7640% for rats, rabbits, and dogs, respectively, indicating that formation of M4 after iv administration of YH439 was maximal in dogs. Third, the AUC (or AUC0-->t) ratios of M5 to YH439 after iv administration of YH439 were 103-127, 2.93-3.31, and 92.4-158% for rats, rabbits, and dogs, respectively, indicating that formation of M5 after iv administration of YH439 was minimal in rabbits.     

Bioavailability and pharmacokinetics of cyproterone acetate after oral administration of 2.0 mg cyproterone acetate in combination with 50 micrograms ethinyloestradiol to 6 young women

The bioavailability and pharmokinetics of cyproterone acetate (CA) were studied in 6 healthy young women. The subjects received a single oral dose of 2 mg carbon-14-CA plus 50 mcg tritiated-ethinyl estradiol. Matimum plasma levels of CA were observed about 4 hours after administration. During the 4-10 hours following administration, carbon-14-CA in plasma disappeared with a half-life of 3 + or -1.6 hours. The half-life for the subsequent phase of disposition was 1.7 + or -.5 days. The apparent volume of distribution for CA was 1300 + or -580 liters. Although plasma equivalents of carbon-14-CA had higher absolute values, the course of their distribution was similar to those concentrations for the unchanged drug. 88 + or -11% of the dose was recovered and 30.4 + or -7.3 excreted in urine. The concentration of the primary metabolite of CA in plasma showed a decline which paralleled the terminal disposition phase of CA; the elmination half-life being 1.8 + or -.1 days. The apparent distribution volume for the primary metabolite was 95 + or -25 liters. CA, in comparison with its primary metabolite, had 10 times the apparent distribution volume. Approximately 90% of CA was present at all times following administration. In terms of total activity, the proportion of CA in plasma remained constant 1/2 day after administration. It is suggested that the transfer of CA from tissues determines the rate of metabolization of CA and the excretion of metabolites.     

Combined chemotherapy with low-dose cisplatin, tegafur and uracil in a case with neck recurrence of laryngeal cancer

The patient was a 60-year-old man with progressive neck recurrence of laryngeal squamous cell carcinoma. As a previous treatment, he had undergone irradiation (primary: 60 Gy; neck: 45 Gy) after two cycles of neoadjuvant chemotherapy (cisplatin 100 mg/m2 daily; day 1:5-fluorouracil 1,000 mg/m2 daily; day 1-5) and planned neck dissection. For a neck recurrence, he had received five cycles of low-dose cisplatin (5 mg/body daily: day 1-5) with tegafur and uracil (600 mg/body daily: day 1-7) every week. As an outpatient, he then received ten cycles of low-dose cisplatin (10 mg/body daily: day 3, 6) with tegafur and uracil (600 mg/body daily: day 1-7) every week. The size of the tumor did not decrease with the above chemotherapy, but no remarkable growth of the cancer was seen, and no toxic effect of the chemotherapy was observed. He continued his job for 30 weeks just as before he had fallen sick. Chemotherapy of low-dose cisplatin with tegafur and uracil was suggested to be useful for the patient with recurrent laryngeal squamous cell carcinoma.     

Lethal drug interactions of sorivudine, a new antiviral drug, with oral 5-fluorouracil prodrugs

Rats were orally co-administered sorivudine (SRV: 1-beta-D-arabinofuranosyl-(E)-5-(2-bromovinyl)uracil), a new oral antiviral drug for herpes zoster, with the oral anticancer drug tegafur (FT: 1-(2-tetrahydrofuryl)-5-fluorouracil) as a prodrug of 5-flourouracil (5-FU) once daily to investigate a toxicokinetic mechanism of 15 Japanese patients' deaths recently caused within a brief period by the drug interaction of these drugs. All the rats showed extremely elevated levels of 5-FU in plasma and tissues, including bone marrow and small intestine, and died within 10 days, whereas the animals given the same dose of SRV or FT alone were still alive over 20 days without any appreciable toxic symptom. Before their death, there was marked damage of bone marrow, marked atrophy of intestinal membrane mucosa, marked decreases in white blood cells and platelets, diarrhea with bloody flux, and severe anorexia as reported with the Japanese patients. Data obtained by in vivo and in vitro studies strongly suggested that (E)-5-(2-bromovinyl)uracil generated from SRV by gut flora was reduced in the presense of NADPH to a reactive form by hepatic dihydropyrimidine dehydrogenase (DPD), a key enzyme determining the tissue 5-FU levels, bound covalently to DPD as a suicide inhibitor, and markedly retarded the catabolism of 5-FU.     

Effect of oral administration of prostaglandin E1 on erectile dysfunction

Collagen-related peptides, Gly-Pro-Arg and its analogues, were examined for their inhibitory effects on platelet aggregation induced by the addition of ADP. Human platelet aggregation was suppressed by more than 50% with each of Gly-Pro-Arg and such Gly-Pro-Arg-containing peptides as Gly-Pro-Arg-Gly, Gly-Pro-Arg-Gly-Pro, Gly-Pro-Arg-Pro-Pro, and Gly-Pro-Arg-Pro-Pro-Pro at a concentration of 0.3 mM. The inhibitory effects of these peptides were about 10 times higher in human PRP than in rat PRP. Other Gly-Pro-Arg analogues such as Sar-Pro-Arg, Gly-Pro-Lys, Gly-Ala-Arg, and Ala-Gly-Pro-Arg had no inhibitory effect at a concentration from 0.1 to 0.8 mM even in human PRP. Intravenous and oral administrations of Gly-Pro-Arg and enzymatic hydrolysates of collagen suppressed the decrease in platelet count for endotoxin-induced DIC in rats. Collagen itself has been regarded as a potent inducer of platelet aggregation, but these findings suggest that collagen-related peptides and enzymatic hydrolysates of collagen prevent platelet aggregation.     

Combination hepatic intra-arterial 5-fluorouracil and CDDP administration with oral regimen in patients with colorectal cancer metastasis to the liver

We investigated therapeutic effectiveness and side effects of a combination weekly high-dose 5-FU plus one shot CDDP HAI (WHF + CDDP method) with oral regimen in patients with colorectal cancer metastasis to the liver. All 24 patients enrolled in this study showed 54% efficacy whereas patients combined HAI with oral regimen over one week obtained 83% efficacy for multiple liver metastasis. They showed good quality of the life during combination chemotherapy without any symptoms of metastatic lesions. The WHF + CDDP method combined with oral regimen is a promising treatment for colorectal cancer metastasis to the liver as well as extrahepatic distant organs, and this protocol may be satisfactorily accepted by most colorectal cancer laden patients because of negligible side effects.     

Successful treatment of pseudomyxoma peritonei using combination chemotherapy of intraperitoneal low-dose CDDP and oral 5'-DFUR administration

We report a case of pseudomyxoma peritonei treated with combination chemotherapy. A 73-year-old woman was diagnosed as having psuedomyxoma peritonei originated from the vermiform appendix. Appendectomy was performed, and 10 mg of MMC was administered intraperitoneally. From day 7, 600 mg/day of 5'-DFUR was orally given for 2 years, and 20 mg of CDDP once a month was intraperitoneally administered seven times. The patient has been doing well with no evidence of tumor recurrence for two years after operation. Combination chemotherapy with CDDP and 5'-DFUR, as a biochemical modulation therapy, has fewer side effects and leads to better quality of life of patients. We recommend a combination chemotherapy with low-dose CDDP and 5'-DFUR for patients in poor general condition.     

Effect of 'unstirred' water layer in the intestine on the rate and extent of absorption after oral administration

The presence of an aqueous diffusion layer or 'unstirred' water layer adjacent to the intestinal membrane has long been regarded as a potential barrier for intestinal absorption of compounds. Theoretical analyses were performed in the present study to quantitatively determine the effect of this layer on the rate and extent of absorption of passively absorbed compounds with different membrane absorption half-lives (10 to 300 min) in humans, dogs, rabbits, rats and mice. Diffusion half-lives across this (40 microns thick) layer were estimated to be 5.8, 2.5, 1.1, 0.65 and 0.32 min, respectively, in the distended intestine of the above five species. These half-lives are reduced by about 5-fold when the intestine is about 80% 'flat' in fasting state. The results of extensive analysis indicate that the presence of such a layer is generally expected to have a relatively mild or insignificant effect on the rate of absorption and an insignificant effect on the extent of absorption. The study also indicates that an aqueous layer of 708 microns has practically no effect on the extent of absorption of progesterone, a highly lipophilic compound, in rats. For prediction of or correlation with the fraction of oral dose absorbed after oral administration, the present study indicates that use of apparent or effective permeability rather than unbiased or true wall (membrane) permeability, as advocated earlier by others, should generally suffice.