The effect of sodium thiosulfate on subcellular localization of platinum in rat kidney after treatment with cisplatin

Female Sprague-Dawley rats were given 10 mg/kg of i.v. cis-diammine-dichloroplatinum(II) (cisplatin) simultaneously with i.v. sodium thiosulfate (STS) at a 200-fold molar excess to cisplatin, then subcellular (nuclei, mitochondria, microsomes, cytosol) distribution of platinum within rat kidney cells was determined 15 min, 1 h, 8 h and 24 h after cisplatin injection. Blood urea nitrogen levels were measured in rats treated in the same manner described above. STS was found to block cisplatin-induced nephrotoxicity. However, differences in platinum concentrations in total homogenate or each subcellular fraction between STS-treated rats and controls were not significant enough to fully account for the drastic protective effect of STS against cisplatin nephrotoxicity.     

Quantitative relationship between pharmacokinetics of unchanged cisplatin and nephrotoxicity in rats: importance of area under the concentration-time curve (AUC) as the major toxicodynamic determinant in vivo

 Purpose: The major pharmacokinetic parameters of unchanged cisplatin (CDDP) related to nephrotoxicity were evaluated in rats in vivo using a pharmacodynamic model. Methods: CDDP was administered according to various dosing schedules (single bolus, intermittent bolus, or continuous infusion). Unchanged CDDP in plasma and urine was quantified using high-performance liquid chromatography (HPLC). The pharmacokinetics were assessed by model-independent methods. The relationship between pharmacokinetics and BUN levels was evaluated using a sigmoid maximum response (E_max) model. Results: Unchanged CDDP showed linear pharmacokinetics after single bolus injections of 1 to 5 mg/kg CDDP. Nephrotoxicity was ameliorated following intermittent bolus injection (1 mg/kg per day for 5 days) and continuous infusions (over 2 and 3 h) of the same CDDP doses (5 mg/kg), although these dosing schedules did not change the area under the concentration-time curve (AUC), total clearance (Clt), urinary excretion of unchanged CDDP or kidney platinum levels significantly. The maximum BUN level, as a nephrotoxicity marker, showed dose-related increases after single bolus injection of 1 to 5 mg/kg CDDP and after 3-h infusion of 5 to 25 mg/kg. The pharmacodynamic relationship between the maximum BUN level and C_max and between the maximum BUN level and AUC were apparently different between single bolus injection and 3-h infusion. The maximum BUN level was related to the AUC calculated by plasma concentrations of unchanged CDDP greater than the threshold level (AUC_>Cmin), a relationship most successfully described by the signoid E_max model, regardless of CDDP dose and schedule. The plasma threshold level of unchanged CDDP was determined as 0.9 μgPt/ml in rats. Conclusions: The present results substantiated the importance of C×T (AUC) value as an indicator of CDDP-induced nephrotoxicity in vivo as well as of tumor cell-killing effect of CDDP in vitro. The AUC_>Cmin of unchanged CDDP was found to be an important pharmacokinetic parameter predicting CDDP nephrotoxicity. Received: 12 February 1996 / Accepted: 5 September 1996     

Efficacy of two-route chemotherapy using cis-diamminedichloroplatinum(II) and its antidote, sodium thiosulfate, in combination with angiotensin II in a rat limb tumor

We combined the angiotensin II (AT-II)-induced hypertension method with "two-route chemotherapy" (TRC), using cis-diamminedichloroplatinum(II) (CDDP) and its antidote, sodium thiosulfate (STS). The efficacy of the modified TRC was evaluated in rats bearing a limb tumor (transitional cell carcinoma). Immediately after infusing CDDP (15 mg/kg) and AT-II (15 micrograms/kg) via the femoral artery for 5 min, 1580 mg/kg STS (200-fold molar ratio to 15 mg/kg of CDDP) were administered i.v. for a further 5 min. Other treatments were as follows: 5 mg/kg of CDDP mixed or not mixed with 15 micrograms/kg of AT-II were given intraarterially (i.a.); 5 mg/kg of CDDP alone were injected i.v.; CDDP (15 mg/kg, i.a.) and STS (1580 mg/kg, i.v.) were simultaneously administered, without AT-II (conventional TRC). The antitumor effects of the modified TRC, evaluated by regression of tumor growth and extended life span, were superior to the other treatments. On the other hand, nephrotoxicity, loss of body weight, and leukopenia, seen in the rats given TRC with AT-II, occurred less than or at the same rate as in rats given other treatments. Thus, the TRC with AT-II was the most effective treatment given to rats bearing a regionally confined tumor. The feasibility of clinical application of modified TRC using i.a. CDDP plus AT-II and i.v. STS is discussed.     

Systemic chemotherapy in tumor-bearing rats using high-dose cis-diamminedichloroplatinum(II) with low nephrotoxicity in combination with angiotensin II and sodium thiosulfate

Systemic chemotherapy using high-dose DDP and its antidote, STS, was combined with the AT-II-induced hypertension method and evaluated for efficacy against s.c. tumors in rats. After i.v. infusion of DDP plus AT-II for 5 min, STS was administered i.v. over a further 5 min. The rats treated with this combination chemotherapy showed normal levels of BUN and serum creatinine 4 days after the treatment, although most rats given i.v. STS after DDP without AT-II showed severe nephrotoxicity. The absence of obvious nephrotoxicity in AT-II-combined chemotherapy using i.v. DDP plus post-administered STS can be explained by a transient inhibition of DDP-delivery to the kidney during the AT-II-induced hypertension. The anti-tumor effect of this modified therapy, evaluated by inhibition of tumor growth, was superior to other treatments, as follows: concomitant i.v. administrations of DDP and STS; i.v. DDP, with or without AT-II. The improvement in anti-tumor effect of this combination therapy is explained by the delayed neutralization of active DDP by STS at the tumor site and the selective enhancement of DDP delivery to the tumor tissue, as produced by AT-II. Thus, systemic chemotherapy using high-dose DDP induced no obvious nephrotoxicity and improved the anti-cancer effect in the case of concomitant administration of DDP plus AT-II and the time-delayed injection of STS.     

Increased therapeutic effect on metastatic liver tumors in rats of two-route chemotherapy usingcis-diamminedichloroplatinum (II) and its antidote,sodium thiosulfate,with temporary clamping of the abdominal aorta

Summary To improve the therapeutic effects of conventional “two-route chemotherapy” (TRC) comprisingcis-diamminedichloroplatinum(II) (CDDP) given via the hepatic artery plus simultaneous i. v. sodium thiosulfate (STS) on metastatic liver tumors in rats, we combined TRC with aortic clamping at the supraceliac level. Treatments were evaluated in Wistar-King-Aptekman (WKA) rats bearing metastatic liver tumors 7 days after the inoculation of 10⁶ syngenic RBT-1 (transitional-cell carcinoma) cells via the mesenteric vein. When 15 mg/kg CDDP was injected i. a. over 5 min, immediately followed by STS 1,580 mg/kg (200-fold the molar equivalent of 15 mg/kg CDDP) given i. v. over a further 5 min, the antitumor activity, evaluated by the number of tumor nodules present 12 days after treatment, was superior to that of conventional TRC (15 mg/kg i. a. CDDP plus simultaneous administration of 1,580 mg/kg i. v. STS), but the blood urea nitrogen (BUN) level was highly elevated (63.6 mg/dl). With aortic clamping for 7.5 min during CDDP administration and the first half of STS treatment, the TRC consisting of CDDP plus delayed STS (modified TRC) exhibited a further improvement in antitumor activity, with no nephrotoxicity (BUN, 17.1 mg/dl). Although the antitumor activity of 3 or 5 mg/kg i. a. CDDP was also increased by aortic clamping, in animals with normal BUN levels the survival of those treated with modified TRC was greater than that of rodents given 3 mg/kg i. a. CDDP with aortic clamping; however, the former was the same as that of animals given 5 mg/kg i. a. CDDP with aortic clamping whose BUN levels were elevated (31.2 mg/dl). Loss of body weight, the decrease in WBC counts, and changes in the serum transaminase levels in rats given modified TRC were tolerable. The improved therapeutic effect of modified TRC can be explained as follows: during aortic clamping, (a) CDDP delivery to the kidney decreased by 96% and made feasible the delay in STS administration after CDDP without nephrotoxicity, and (b) CDDP retention in the liver was increased by 366%, as aortic clamping decreased the portal blood flow, thereby inhibiting the washout of CDDP from the liver. This study was supported in part by a Grant-in-Aid for Cancer Research from the Ministry of Education, Science and Culture, Japan     

Pharmacokinetics of cis-diamminedichloroplatinum(II) after administration in hypertonic saline

Nephrotoxicity, the dose-limiting toxicity of cis-diamminedichloroplatinum(II) (CDDP), is ameliorated when administered in hypertonic saline with normal saline hydration. To determine whether the diminished nephrotoxicity is associated with alteration of the pharmacokinetics of CDDP, we examined the pharmacokinetics of free and total platinum, platinum renal excretion, and urine electrolytes in patients given CDDP in hypertonic saline and in patients given CDDP in a conventional manner. The pharmacokinetics of free and total platinum for equal doses of CDDP were similar regardless of the vehicle of administration and the method of hydration. CDDP given in a vehicle of high chloride concentration with normal saline hydration resulted in a statistically significant increase in both urine volume and chloruresis compared to the conventional regimen. The decreased nephrotoxicity associated with administration of CDDP in hypertonic saline with saline diuresis may be related to increased chloruresis, urinary volume, or a combination of both, but did not appear to be related to an alteration in the pharmacokinetics.     

A bioassay of cisplatin by human tumor clonogenic assay

A new bioassay method for cis-diamminedichloroplatinum (CDDP) using a human tumor clonogenic assay (HTCA) was developed and used to examine the pharmacokinetics of the active form of CDDP in different schedules of administration. The inhibition of colony growth of tumor cells decreased with increase in the % of fetal calf serum in RPMI1640 containing CDDP. By means of this assay, four administration schedules (A, B, C and D) of CDDP were examined. In patients given 40 mg/m2 of CDDP by iv infusion on day 1 twice with a 1 hr interval (schedule A), total platinum was still detectable in plasma at 6 hr by atomic absorption assay. However, the active form of CDDP was no longer detectable at 30 min. In patients treated with 20 mg/m2 of CDDP iv for 20 min daily (schedule B) from day 1 to day 4, the level of total platinum showed a cumulative increase. However, the active form of CDDP was no longer detectable at 30 min, and no cumulative effect was observed. In patients given a high dose (120 mg/m2) of CDDP iv for 30 min on day 1 (schedule C), the peak concentration of active form of CDDP was determined to be 5.0 to 7.0 micrograms/ml, and a level of more than 1.0 micrograms/ml was maintained even after 2 hr in one case. In 2 patients of this group the concentrations of active form of CDDP determined by HTCA were the same as those of ultrafiltrable platinum detected by atomic absorption assay. In 2 of 3 patients given 100 mg of CDDP into the pleural cavity, the active form of CDDP was detected in sera. High-dose CDDP administration was concluded to be preferable to low-dose therapy because of the higher peak concentration and longer residence time of the active form of CDDP in the plasma. Furthermore, it is suggested that a systemic effect of CDDP can be expected even when CDDP is given by intrapleural administration.     

Pharmacokinetics and tissue distribution of cisplatin in nude mice: platinum levels and cisplatin-DNA adducts

The pharmacokinetics of platinum (Pt) and cisplatin (CDDP)-DNA adducts were studied in nude mice after single-dose CDDP treatments. Whole blood, serum, kidney, lever, testis, brain, and tumor were collected at different intervals after injection of CDP at different dose levels. Pt was measured with flameless atomic absorption spectrometry (FAAS) or adsorptive voltammetry (AdV) and CDDP-DNA adducts with quantitative immunohistochemistry. The drug was immediately absorbed into the blood circulation (peak serum Pt levels were reached within 5 min) after i.p. CDDP administration, and distribution into most tissues also occurred rapidly (tissue Pt levels peaked at 15 min). With a sampling period of 7 days there was a biphasic elimination of Pt from blood, serum, and tissues. In the brain the pharmacokinetics differed with a gradual accumulation of Pt occurring during the 1st week. Formation of CDDP-DNA adducts in tissues was a slower process, with maximal levels being achieved at between 30 min and 4 h after drug administration, followed by a steady state lasting for at least 24 h. Each tissue type had its specific immunohistochemical staining pattern of adducts. With escalating CDDP doses there was a linear, or almost linear, increase in Pt concentrations and CDDP-DNA adduct levels in all sample types examined. These results suggest that a fair estimation of the amount of drug in tumor and normal tissues can be made from analysis of serum Pt at a fixed time point after a single dose of CDDP.     

Intracellular metabolites of cisplatin in the rat kidney

Summary The appearance of low-molecular-weight metabolites of cisplatin in the cytosol of cells from the cortex and outer medulla, of the rat kidney has been examined using HPLC up to 24 h following cisplatin administration. Comparison was made between these metabolites and those present in plasma, urine and liver. The effect of sodium chloride (NaCl) pretreatment, which is known to reduce cisplatin-induced nephrotoxicity, on these metabolites was also investigated. Platinum levels in the kidney cortex and medulla and the cytosol reached maximal levels within 1 h of i.p. injection of 5 mg/kg cisplatin. At least six platinum species, including cisplatin, were present 1 h post-dosing, with the principal species being the parent drug; all of these species were either neutral or negatively charged. Although the concentration of most of the platinum species fell with time, that of one species eluting before cisplatin rose, and by 24 h it was the major metabolite. Cisplatin and two other major cytosolic platinum species were also present in urine and plasma, both of which also contained a number of charged species that were absent from the cytosol. The liver cytosol contained at least five metabolites 1 h post-dosing, but, in contrast to the kidney cytosol at the same time, the predominant species was that eluting before cisplatin and not cisplatin itself. One of the metabolites in the cytosol and urine had the same retention time as an adduct of cisplatin with glutathione and with cysteine. Urinary samples also contained a metabolite coeluting with aquated cisplatin. Pretreatment of animals with NaCl significantly reduced the platinum concentration in the kidney, with a corresponding decrease in the cytosolic metabolites; this may have contributed significantly to the reduction in cisplatin-induced nephrotoxicity after NaCl pretreatment. NaCl also significantly reduced a possible aquated species present in the urine, which may also have contributed to the reduction in nephrotoxicity. The data suggest that cisplatin itself may be the nephrotoxic species, since it is the intracellular platinum compound present in highest concentration during the early critical period after its administration.     

Two-route chemotherapy using the anticancer drug cis-diamminedichloroplatinum(II) and its antidote, sodium thiosulfate

We described the efficacy of "two-route chemotherapy (TRC)", in which the anticancer drug, cis-diamminedichloroplatinum (II) (DDP), is injected locally, in combination with its antidote, sodium thiosulfate (STS), given systemically. First, we tested the protective effect of sulfur-containing compounds against DDP toxicity, and found STS to be the most potent antidote of DDP. On the basis of this finding, we developed TRC using DDP and STS, and applied it for liver and lung metastasis, bladder cancer, and peritoneal disseminated tumors in experimental animals, resulting in remarkable antitumor effects without serious side effects, especially nephrotoxicity. Furthermore, we obtained an optimal increase in the lifespan of rats bearing limb tumors when we tried TRC in combination with the angiotensin II (AT-II)-induced hypertension method. We also clarified that the protection of STS against DDP toxicity was mainly due to the diminution of the active platinum level in blood. We briefly reviewed the clinical trials of TRC, and discussed the improvements which still have to be made.     

Plasma and tumor concentrations of cisplatin following intraperitoneal infusion or bolus injection with or without continuous low-dose-rate irradiation

Our purpose of this study was to determine whether whole-body, continuous low-dose-rate irradiation (CLDRI) alters the plasma and/or tumor platinum pharmacokinetics after ip bolus injection or ip infusion as a possible mechanism of interaction between CLDRI and cisplatin. The C3Hf/Sed mice bearing SCCVII/SF tumors were given 6 mg cisplatin/kg ip by bolus injection or an ip infusion of 0.25 mg cisplatin.kg-1.hour-1 for 48 hours with and without CLDRI at 0.56 Gy/hr for 24 or 48 hours. Plasma and tumor platinum concentrations were determined with an atomic absorption spectrophotometer at appropriate intervals during infusion and up to 48 hours after drug administration. Both total and ultrafilterable plasma platinum followed a biphasic elimination after ip bolus injection, whereas only a prolonged single-phase elimination was seen after ip infusion. Tumor uptake of platinum appeared to follow a passive diffusion pattern with a prolonged cellular retention of platinum. Whole-body CLDRI had no apparent effect on the pharmacokinetics of plasma and tumor platinum administered by ip bolus injection or prolonged continuous infusion.     

Pharmacokinetics of cisplatin and the effect of sodium thiosulfate

The pharmacokinetics of cisplatin (cis-dichlorodiammineplatinum (II), CDDP) have been studied in 11 patients. Plasma and urine CDDP concentrations were determined by flameless atomic absorption spectrophotometry. The treatment schedule was administered either by a 3-hour and 4-hour i.v. infusion or a 1.5-hour i.a. infusion. In the 3-hour i.v. infusion, the peak level of plasma total CDDP was 4.09 micrograms/ml after the end of infusion and non-protein-bound CDDP was 0.78 microgram/ml. Plasma total CDDP level declined with two peaks, the half-life of the alpha phase being 3.3 hours and that of the beta phase being 5.29 days. The half-life of non-protein-bound CDDP was 1.6 hours. CDDP might have remained for a long time, because CDDP values were obtained 3 weeks after infusion and urinary recovery of CDDP showed low values. Its urinary recovery was 40.3% of the dose infusion in the first 24 hours and 48.0% in 96 hours. The protein-binding of CDDP was inhibited by sodium thiosulfate(STS) and renal urinary excretion was enhanced. Our data suggest that STS can be applied as a neutralizer of CDDP.     

Cisplatin-incorporating polymeric micelles (NC-6004) can reduce nephrotoxicity and neurotoxicity of cisplatin in rats

In spite of the clinical usefulness of cisplatin (CDDP), there are many occasions in which it is difficult to continue the administration of CDDP due to its nephrotoxicity and neurotoxicity. We examined the incorporation of CDDP into polymeric micelles to see if this allowed the resolution of these disadvantages. Cisplatin was incorporated into polymeric micelles through the polymer-metal complex formation between polyethylene glycol poly(glutamic acid) block copolymers and CDDP (NC-6004). The pharmacokinetics, pharmacodynamics, and toxicity studies of CDDP and NC-6004 were conducted in rats or mice. The particle size of NC-6004 was approximately 30 nm, with a narrow size distribution. In rats, the area under the curve and total body clearance values for NC-6004 were 65-fold and one-nineteenth the values for CDDP (P<0.001 and 0.01, respectively). In MKN-45-implanted mice, NC-6004 tended to show antitumour activity, which was comparable to or greater than that of CDDP. Histopathological and biochemical studies revealed that NC-6004 significantly inhibited the nephrotoxicity of CDDP. On the other hand, blood biochemistry revealed transient hepatotoxicity on day 7 after the administration of NC-6004. Furthermore, rats given CDDP showed a significant delay (P<0.05) in sensory nerve conduction velocity in their hind paws as compared with rats given NC-6004. Electron microscopy in rats given CDDP indicated the degeneration of the sciatic nerve, but these findings were not seen in rats given NC-6004. These results were presumably attributable to the significantly reduced accumulation of platinum in nerve tissue when NC-6004 was administered (P<0.05). NC-6004 preserved the antitumour activity of CDDP and reduced its nephrotoxicity and neurotoxicity, which would therefore seem to suggest that NC-6004 could allow the long-term administration of CDDP where caution against hepatic dysfunction must be exercised.     

Combination effects of cis-dichlorodiammineplatinum (II) and sodium thiosulfate on renal dysfunction

Forty-five patients with lung carcinoma were randomized to receive CDDP alone (STS (-) group) or combination of sodium thiosulfate (STS (+) group). Among the 45 patients, 42 had primary lung carcinoma and four had metastatic lung carcinoma. The combination of CDDP and STS infusion was performed in twenty-three patients and CDDP alone in 22 patients. The patients given STS were evaluated for renal function and pharmacokinetics. Urinary excretion of beta 2 microglobulin (BMG) and urinary concentration of N-acetyl-beta-D-glucosaminide (NAG), which reflect the function of the proximal tubules, were almost normal in the STS (+) group, but abnormally high in the STS (-) group. For serum BMG, BUN, creatinine, and 24-h creatinine clearance, which reflect glomerular function, no significant differences were found between the two groups. Urinary platinum excretion over 24 h was 29% in the STS (+) group and 21% in the STS (-) group. Total concentration of serum platinum after 24-h administration of CDDP was 2.1 micrograms/ml in the STS (+) group and 2.4 micrograms/ml in the STS (-) group. This study indicated that the combination of CDDP and STS promotes urinary excretion of CDDP, and rescues the dysfunction of the proximal tubules.     

Protective effect of L-carnitine versus amifostine against cisplatin-induced nephrotoxicity in rats

We aimed to compare the protective effect of L-carnitine (CAR) and amifostine (AMF) against cisplatin (CDDP)-induced nephrotoxicity through biochemical markers and histopathological evaluation. Fifty-seven Wistar albino male rats were randomly classified into six groups, which were AMF+CDDP (n = 11; 200 mg/kg AMF 30 min prior to 7 mg/kg CDDP), CAR+CDDP (n = 11; 300 mg/kg CAR 30 min prior to 7 mg/kg CDDP), CDDP (n = 11; 1 mL/kg isotonic saline 30 min prior to 7 mg/kg CDDP), AMF (n = 8; 200 mg/kg AMF alone), CAR (n = 8; 300 mg/kg CAR alone), and control (n = 8; 1 mL/kg isotonic saline alone). All drugs were given intraperitoneally. Five days after medication, animals were killed, and samples of blood and kidney tissues were collected for biochemical and histopathological evaluation. The serum urea level was highest in AMF+CDDP group among CDDP-applied groups without statistical significance (median, range: 88, 56-21 mg/dL; P > 0.05). There was no statistical significance among CDDP-applied groups in terms of creatinine level (P > 0.05). In the AMF+CDDP group, the median glomerular, tubular, and tubulointerstitial inflammatory damage scores were significantly higher than the other CDDP-applied groups (P < 0.001). The difference between CAR+CDDP and CDDP groups was not statistically significant in terms of renal damage scores. AMF+CDDP group had significantly higher median total nephrotoxicity score than all the other groups (P < 0.001). To conclude, AMF or CAR has no protective effect on CDDP-induced nephrotoxicity. Furthermore, our findings suggest that application of AMF before CDDP may enhance CDDP-induced nephrotoxicity histopathologically.     

Effects of sodium thiosulfate in combination therapy of cis-dichlorodiammineplatinum and vindesine

Summary The effects of sodium thiosulfate (STS) were studied in patients who received a combination therapy of cis-dichlorodiammineplatinum (CDDP) and vindesine. In this study, 61 patients with non-small-cell lung carcinoma were randomized to receive either CDDP and vindesine (both given i.v.) with i.v. STS [30 patients, STS(+) group] or CDDP and vindesine without STS [31 patients, STS(-) group]. In the STS(+) group, 16 patients who showed an improvement (reduction in tumor size or relief of symptoms) after the first course received the second STS(+) treatment, and 15 patients in the STS(-) group who showed an improvement after the first course received the second STS(-) treatment. Urinary levels of ₂-microglobulin (BMG) and N-acetyl--D-glucosaminidase (NAG) were measured as an index of proximal tubular function. Analysis of both levels indicated that STS suppressed CDDP nephrotoxicity to a minimal level. Serum BMG, blood urea nitrogen (BUN), and total as well as 24-h creatinine clearance levels were measured as an index of glomerular function. There were no significant differences in these levels between the STS(+) and STS(-) groups. The urinary recoveries of total platinum 24 h after CDDP administration were 29% and 21% in the STS(+) and STS(-) groups, respectively. The mean plasma concentrations of total platinum at 24 h after CDDP administration were 2.24 and 2.70 g/ml in the STS(+) and STS(-) groups, respectively. There were no significant differences in the response rates of the STS(+) and STS(-) groups at a fixed dose of 100 mg/m² CDDP. Therefore, the present study clearly demonstrates that systemic administration of STS reduces the side effects of CDDP to a minimal level without impairing its antitumor activity and that STS treatment is applicable in a repeated chemotherapy using CDDP alone or in combination with other antitumor agents.     

Superselective intra-arterial infusion chemotherapy of high-dose cisplatin for advanced paranasal sinus carcinomas]

Eighteen patients with advanced paranasal sinus carcinomas were treated by "two-route" intra-arterial chemotherapy using cis-diamminedichloroplatinum (CDDP) and sodium thiosulfate (STS) to preserve the hard palate and the eye. In these patients, 100 mg/m2 of CDDP was administered weekly through each feeding artery of the tumor superselectively at 5 mg/min. During infusion of CDDP, STS at a two-hundred fold dose of CDDP was injected through a catheter placed in the brachiocephic vein introduced via the subclavian vein. The complete and partial response rates were 14/18 (78%) and 4/18 (22%), respectively. None of the nine patients following operation showed residual tumors histologically. The peak of the mean total plasma platinum concentration was 5.5 micrograms/ml, and this concentration was rapidly reduced to 1.5 micrograms/ml in 5 hours. The peak of the plasma protein unbound platinum was 3.9 micrograms/ml. This concentration rapidly decreased to almost zero within 5 hours after IA infusion. The mean tumor platinum content achieved by superselective IA infusion was as high as 6.0 micrograms/g tumor, and this decreased rapidly to 2.4 micrograms/g tumor on the 5th day after the 1st intra-arterial infusion. All patients were free from chemotoxicity such as renal, hematological dysfunctions, or gastrointestinal symptoms. Each chemotherapy treatment could be done weekly on schedule. All but one patient was alive for 5-40 months. This new method of chemotherapy appears very effective for advanced paranasal sinus carcinomas.     

The influence of sodium thiosulfate on the antitumor effect of cisplatin in human gastric cancer cell lines

It is well known that the sodium thiosulfate (STS) decrease not only the nephrotoxicity which is a dose limiting factor of cisplatin (CDDP) chemotherapy but also its antitumor activity. Therefore, we examined the antitumor effect of CDDP in the human gastric cancer cell lines under various concentrations of STS. The cell lines used were KATO-III, MKN 28, MKN 45 and MKN 74. The consistency of STS in relation to CDDP (2.0 ng/ml) was 25-250 fold-molar ratio. The chemosensitivity of CDDP was positive in the 3 cell lines, KATO-III, MKN 28 and KATO-III in order. When STS was used with 50 fold-molar ratio in KATO-III and MKN 28 and 100 fold in MKN 45, a CDDP colony inhibition rate of more than 80% was maintained. This results suggest that the antitumor effect of CDDP will not be suppressed not so much when the low dose of STS was used in CDDP with STS chemotherapy, even though used through the same route of administration and simultaneously.     

Relationship between pharmacokinetics of unchanged cisplatin and nephrotoxicity after intravenous infusions of cisplatin to cancer patients

 Purpose: The relationships between pharmacokinetic parameters of unchanged cisplatin (CDDP) and several markers for nephrotoxicity after CDDP infusion (80 mg/m²) over 2 and 4 h were quantitated in patients with various cancers (lung, stomach and colon cancers and mediastinal tumor). Methods: Plasma and urinary levels of unchanged CDDP were measured using a specific high-performance liquid chromatography method. Pharmacokinetic parameters were calculated according to the model-independent method. The nephrotoxicity markers, blood urea nitrogen (BUN), serum creatinine (SCr), plasma and urinary β₂-microglobulin (BMG_p and BMG_u), urinary N-acetyl-β-D-glucosaminidase (NAG) and creatinine clearance (CCR) were monitored for 30 days following CDDP administration. Results: The maximum plasma concentration (C_max), maximum urinary excretion rate (dAe/dt_max), area under the plasma concentration-time curve from time zero to infinity (AUC), cumulative amount excreted in urine from time zero to infinity (Ae), total clearance (Clt), renal clearance (Clr) and plasma half-life (t_1/2) of unchanged CDDP were not significantly different between the 2-h and 4-h infusion schedules. The values of the nephrotoxicity markers changed significantly following CDDP administration, suggesting that CDDP chemotherapy (80 mg/m²) caused nephrotoxicity. The C_max of unchanged CDDP was the most informative pharmacokinetic parameter for nephrotoxicity. C_max was related to maximum BUN, maximum SCr and minimum CCR levels in 27 CDDP treatments according to an exponential model. Conclusion: In order to attain more effective CDDP chemotherapy with minimum nephrotoxicity, the present pharmacokinetic and pharmacodynamic studies suggest that the C_max or steady-state plasma level of unchanged CDDP should be maintained between 1.5 and 2 μg/ml in a standard continuous infusion schedule over 2 h and 4 h. Received: 2 May 1995/Accepted: 25 March 1996     

Studies on an appropriate intra thoracic administration of cisplatin and sodium thiosulfate in malignant pleural effusion

Twenty-eight patients with malignant pleural effusion received instillation of cisplatin (CDDP) into the pleural cavity to examine the pharmacokinetics and side effects of CDDP Thirteen patients received high-dose CDDP (120 mg/m2-160 mg/m2) in combination with sodium thiosulfate (STS), while 15 others received CDDP alone (80 mg/m2). Total Pt and non-protein-bound Pt (free Pt) concentrations in the pleural effusion and plasma were determined by flameless atomic absorption spectrometry. In one patient, Pt concentrations of intact CDDP and STS-bound CDDP were determined using high performance liquid chromatography and flameless atomic absorption spectrometry. Instillation of CDDP at 160 mg/m2 into the pleural cavity was achieved by concurrent use of STS in the large dose (STS 20 g/m2 1 hr later, totalling 625-fold molar ratio to CDDP). When CDDP was combined with STS, there was alleviation in hematological, renal and auditory toxicity but not in nausea, vomiting or anorexia. When CDDP was instillated into the pleural cavity at 150 mg/m2 (in combination with STS equivalent to 200-fold molar ratio to CDDP), a high Pt concentration of intact CDDP could be maintained in the pleural effusion over a prolonged period of time, recording 8.80 micrograms/ml even as late as 12 hr after instillation. On the other hand nearly all of the free Pt concentration for the first 2 hr was considered to be due to intact CDDP. Once systemically administered, STS quickly moved into the pleural effusion, binding with CDDP in the pleural cavity and thus probably reducing its anti-tumor effect. STS did not greatly affect the plasma concentration of total Pt when it was administered at a 100-fold molar ratio to CDDP, yielding only p poor effect. Our findings suggest that malignant pleural effusion could be effectively treated by the instillation of CDDP 80 mg/m2 into the pleural cavity.