Human tissue distribution of 4'-(9-acridinylamino)-methanesulfon-m-anisidide (NSC 141549, AMSA)

Concentrations of AMSA were determined by HPLC in autopsy tissue samples from five patients who had received the drug antemortem. Relative organ concentrations of AMSA varied from patient to patient; however, concentrations were generally highest in gallbladder, liver, and kidney, while low levels were generally but not invariably found in lung, testicle, muscle, fat, spleen, bladder, pancreas, colon, prostate, and brain. One patient with ventricular fibrillation and seizures had high tissue AMSA concentrations in myocardium, but low concentrations in brain. Another patient with seizures during treatment had high brain concentrations of AMSA. Relative organ concentrations were similar to those found in mice, except that mice have high AMSA concentration in their spleens whereas our patients did not, even when the spleen was infiltrated with leukemic cells. High tissue concentrations of AMSA were still present 2 weeks after treatment. AMSA concentration was lower in a renal oncocytoma (1.1 micrograms/g) than in surrounding kidney (2.4 micrograms/g).

Clinical pharmacology of 2,5'-diaziridinyl-3,6-biscarboethoxyamino-1,4-benzoquinone (AZQ)

2,5'-Diaziridinyl-3,6-biscarboethoxyamino-1,4-benzoquinone (AZQ) is an alkylating compound which has exhibited a broad spectrum of antitumor activity against a variety of experimental tumors, particularly those implanted intracranially. We have studied the clinical pharmacology of AZQ in 11 patients with various types of tumors. AZQ was administered at 1-12 mg/m2 daily for 5 days by i.v. infusion in 10-30 min. 14C-labelled AZQ was given on day 1 only. Blood and urine specimens were analyzed radiochemically and chromatographically. The plasma disappearance of unchanged AZQ was essentially biphasic, with an initial plasma t 1/2 of 1.4 +/- 0.4 hr and a terminal t 1/2 of 45.5 +/- 3.1 hr. The apparent volume of distribution was 14.2 +/- 3.0 l/kg. The cumulative urinary excretion of unchanged AZQ was 4.3% in 24 hr and 8.6% in 96 hr. The total clearance of the drug was 200 ml/kg/hr. Cerebrospinal fluid AZQ concentration peaked 45-90 min after drug administration, reaching about 70% of that in plasma, and then declined at nearly the same rate.

Clinical pharmacokinetics of vinblastine by continuous intravenous infusion

Vinblastine (VLB) is moderately active clinically against advanced breast cancer. Since VLB is extensively taken up by platelets and thus only partially available to tumor cells, to enhance the therapeutic index of VLB we have therefore administered this agent by continuous i.v. infusion to patients with advanced breast cancer. In conjunction with the clinical trial, we conducted pharmacokinetic studies of generally tritiated VLB, using radiochemical and chromatographic techniques. The elimination of VLB from the plasma of patients who received it by 5-day i.v. infusion at 1 to 2 mg/sq m daily was biphasic. In four patients who achieved partial remission, the average plasma half-life of VLB during the terminal phase was 29.4 +/- 14.6 days, with a total clearance of 36 +/- 8 ml/kg/hr, and a steady-state apparent volume of distribution of 28.1 +/- 8.5 liters/kg. However, in three patients whose disease merely stabilized, the plasma half-life was 6.4 +/- 1.6 days, the total clearance was 137 +/- 2.9 ml/kg/hr, and the volume of distribution was 33.0 +/- 11.6 liters/kg. In contrast, in five patients with refractory disease, these parameters were 2.3 +/- 0.3 days, 541 +/- 124 ml/kg/hr, and 37.6 +/- 8.6 liters/kg. Since the apparent volumes of distributions at steady state did not differ significantly among these three groups, whereas the values of the total clearance were markedly dissimilar, the plasma half-lives of VLB were significantly shorter in patients not responsive to continuous infusion therapy with this drug. Although the number of patients studied was small, it nevertheless appears that favorable clinical response of patients with advanced breast cancer is associated with slow total clearance of the drug.

Clinical pharmacokinetics of 5-methyltetrahydrohomofolate

DL-N5-Methyltetrahydrohomofolate (MTHHF; NSC-139490; N- [(4-[(2-(2-amino-3,4,5,6,7,8-hexahydro-4-oxo-5-methyl-6- pteridinyl)ethyl) amino) benzoyl)] -L-glutamate), a new folate antagonist of relatively low toxicity, is active against experimental tumor systems resistant to methotrexate and consequently now in clinical trial. We investigated its clinical pharmacokinetics in six patients; four of them received by rapid i.v. infusion tracer doses of [N5-methyl-14C]MTHHF ranging from 13 to 16 mg/sq m, and 2 received 150 mg/sq m; the total radioactivity dose was 100 to 200 mu Ci/patient. MTHHF was assayed by radiochemical and chromatographic techniques. The elimination of MTHHF from the plasma followed a triexponential pattern, with a harmonic mean initial half-life of 20.1 min, an intermediary half-life of 4.5 hr, and a terminal half-life of 74.6 hr. The apparent volume of distribution was 1.6 liters/kg, suggesting rapid and extensive tissue binding. This, together with the low total clearance of 0.2 ml/kg/min, contributed to the long half-life of this agent. Although 68% of the administered dose was excreted in the urine on the first day, only an additional 1% was excreted on the ensuing 3 days. In the two patients who received the higher dose, very little MTHHF was found in the cerebrospinal fluid. In concentrations ranging from 25 to 500 micrograms/ml, the drug was about 50% bound to plasma protein. MTHHF was not metabolized in humans as also reported in animals. These results suggest that MTHHF is excreted in the bile to certain extent. Moreover, since it tends to localize and persist in the body, to forestall cumulative toxicity, frequent administration of this agent should be undertaken only with caution.

Intracerebral penetration and tissue distribution of 2,5-diaziridinyl 3,6-bis(carboethoxyamino) 1,4-benzoquinone (AZQ, NSC-182986)

[14C]AZQ (2-4 mg/m2, 100-200 mCi) was administered at varying times to five patients undergoing surgical resection of intracerebral tumors. Plasma, cerebrospinal fluid (CSF), edematous brain, and tumor specimens were obtained during surgery and the concentration of AZQ was determined radiochemically and chromatographically. Total [14C]AZQ equivalent concentration in tumor for two patients was determined to be 47.5% and 85% of concurrent plasma concentration which was similar to that found in normal brain (60.4% and 75.5% respectively). Only 18-45% of the total radioactivity in tumor tissue and 30-56% in plasma were accounted for by unchanged AZQ. These findings suggest that AZQ may be metabolized to a certain extent. Tissue samples from various organs were obtained during autopsy in a patient who expired ten days after AZQ administration. The highest AZQ concentration was found in the liver, followed by the kidney. Comparable amounts were found in normal brain and brain tumor (22 ng/g vs. 31 ng/g respectively). These results indicate that AZQ penetrates readily into the normal brain and brain tumor with a tendency to persist.

The pharmacologic fate of 2,5-diaziridinyl-3,6-bis(carboethoxyamino) 1,4-benzoquinone (AZQ NSC-182986) by intracarotid or intravenous administration in beagles

Beagle dogs received either intravenous (I.V.) or intracarotid (I.C.) 14C ring labelled 2,5-diaziridinyl-3,6-bis-(carboethoxyamino) 1,4-benzoquinone (AZQ) at a dose of 2 mg/kg. Blood, urine and cerebrospinal fluid (CSF) samples were collected at intervals. At varying times, dogs from each group were sacrificed and histologic examination and drug determinations were performed on the major organs. By both routes of administration, the elimination of AZQ from plasma was biphasic with an initial half-life of 18 min and a terminal half-life of 26 hr. The apparent volume of distribution was 7.9 l/kg and the total clearance was 3.5 ml/kg/h. The 96 hr cumulative urinary excretion of total 14C was 41% of the administered dose, including 4% as the unchanged drug. At 1, 48, and 96 hr after I.C. AZQ, drug concentrations in the brain tissue were twice those by the I.V. route. High drug concentrations in the CSF were produced by both routes, although the CSF to plasma ratio was higher by I.C. than I.V. In extracranial organs, tissue concentrations of AZQ were at least twice as high by I.V. than by I.C. administration. No significant clinical or neurologic toxicity were noted when AZQ was given I.C. In the dog I.C. administration of AZQ seems to accelerate drug entry into the brain tissue.

Concentration of vinblastine in human intracerebral tumor and other tissues

Uptake of vinblastine into human cerebrospinal fluid, intracerebral tumor and autopsy tissues was quantitated radiochemically after separating vinblastine from its metabolites by high pressure liquid chromatography. Only low concentrations of vinblastine were found in cerebrospinal fluid from a single patient. A second patient who received a tracer dose of radiolabelled vinblastine prior to surgical resection of an intracerebral tumor had slightly less radioactivity in tumor than in temporalis muscle, but more in tumor than in edematous brain surrounding the tumor. The radioactivity in tumor increased gradually and exceeded concurrent plasma radioactivity by 2 hr after drug administration. A third patient died 4 hr into a planned 24-hr infusion of radiolabeled vinblastine. Highest vinblastine concentrations were found in organs with high blood flow such as kidney and heart. Intermediate concentrations were found in liver and lung, and low concentrations were found in prostate, gastrointestinal tract, spleen, muscle, bladder, and hepatic and lymph node metastases. A fourth patient died one month after receiving radiolabeled vinblastine. Highest concentrations were in liver and next highest concentrations were in intracerebral tumor. Moderately high concentrations were found in pancreas, thyroid, lung, spleen, ovary, kidney, and kidney metastases. Lowest concentrations were found in omental metastases, heart, breast, and brain. Vinblastine concentration decreased with increasing distance into brain from the brain metastases. Thus, vinblastine was not selectively localized in tumors. The concentrations in tumor did not reflect the concentration in the organ in which the tumor was located. There was no indication that uptake into intracerebral tumor was impaired. Cerebrospinal fluid and brain concentrations of vinblastine did not give any indication of the concentration attainable in intracerebral tumor.

Tumor penetration of AMSA in man

4'-(9-Acridinylamino)-methanesulfon-m-anisidide (AMSA) has shown significant antitumor activity against several murine tumors and leukemias. During its Phase I and II clinical trial, we were able to obtain tumors, plasma, and CSF specimens from patients who received varying doses of AMSA, as well as patients who received high doses and had autologous bone marrow rescue. The drug was analyzed chromatographically. The tumor to plasma drug concentration ratios ranged from 200% to 486%, apparently independent of dose and sampling time. Because AMSA was not detected in the CSF, the drug may not be effective in the treatment of meningeal metastasis. High-dose AMSA therapy with bone marrow rescue did not result in significantly higher AMSA concentrations in the tumor, nor did it elicit favorable response.

Pharmacology of mitoxantrone in cancer patients

Radioactive mitoxantrone was administered at doses of 1-12 mg/m2 by rapid IV infusion to 11 patients. Of the 11 patients, six had normal liver and kidney function tests while the remaining five had abnormal third space and/or hepatic dysfunction. In the former group, the initial t1/2 was 13.7 min and terminal t1/2 was 37.4 h. The apparent volume of distribution was 13.8 l/kg. The total clearance rate was 230.7 ml/kg/h. The recovery of unchanged mitoxantrone from urine was 6.8% at 24 h and 7.3% at 72 h, while the corresponding recovery of total radioactivity was 9.4% at 24 h and 11.3% at 72 h. In the five patients with abnormal liver function or third space the initial t1/2 was variable and ranged from 11.5-63.6 min, and the terminal t1/2 ranged from 53.3-173.2 h, whereas the total clearance rate varied from 52.7-170.2 ml/kg/h. However, the cumulative urinary excretion of unchanged mitoxantrone was similar to that of patients with normal hepatic function: 3.9 at 24 h and 5 at 72 h. Biliary excretion was studied in one of these patients, who had jaundice and hepatic impairment; only 2.3% of 14C was excreted in 24 h and 2.7% in 96 h, of which 39% and 41%, respectively, were unchanged mitoxantrone. Our results suggest that mitoxantrone is taken up rapidly by tissue from which it is released slowly. Reduction of mitoxantrone dose is therefore advisable in patients with liver dysfunction or abnormal third space.

Pharmacokinetics and metabolism of beta-2'-deoxythioguanosine and 6-thioguanine in man

Resistance to the antileukemic agent 6-thioguanine (TG) inevitably develops in animal tumors. However, a new agent, beta-2'-deoxythioguanosine (beta-TGdR) can overcome TG resistance in animal tumor models and is therefore of potential clinical use. The pharmacokinetics of radiolabeled TG were compared with those of beta-TGdR in patients with cancer after intravenous administration. [35S]-beta-TGdR (5.4 mg/kg, 200 mg/m2, 200 microCi total) was administered to five patients; the radiolabel in the plasma declined with an initial half-life (t1/2) of 14 min and a terminal t1/2 of 19.3 h. Within 24 h, 65% of the radiolabel was excreted in the urine. In contrast, after administration of [35S]-6-TG (3.4 mg/kg, 125 mg/m2, 200 microCi total) the average initial t1/2 was 40 min while the terminal phase t1/2 was 28.9 h. Urinary excretion of the radiolabel was 75% of the dose 24 h after administration. Both thiopurines were rapidly and extensively degraded and excreted as 6-thioxanthine, inorganic sulfate, S-methyl-6-thioxanthine, and 6-thiouric acid in addition to other products. Small amounts of unchanged drug were also excreted. These studies suggest that beta-TGdR is merely a latent form of TG.

Clinical kinetics of 1, 4-dihydroxy-5,8-bis [(2-[(2-hydroxyethyl) amino] ethyl] amino ]-9, 10-anthracenedione

The clinical kinetics of 1, 4-dihydroxy-5,8-bis[[ 2-[(2-hydroxyethyl) amino] ethyl] amino]-9,10-anthracenedione dihydrochloride (DHAQ) are reported. DHAQ, 1 to 3 mg/m2, was administered as an intravenous bolus to six patients with metastatic cancer. Plasma clearance of the drug followed a biphasic pattern with a harmonic mean initial half-life (t 1/2) of 13.7 min and a terminal t 1/2 of 37.4 hr. Recovery of unchanged drug in the urine was 6.8% at 24 hr and 7.3% at 72 hr, while the corresponding recovery of total radioactivity was 9.4% and 11.3%. Apparent volume of distribution of DHAQ was about 13.8 +/- 2.9 l/kg. Total clearance was 238.7 ml/kg/hr, twice the creatinine clearance.

Disposition and metabolism of thiopurines III. beta-2'-Deoxythioguanosine and 6-thioguanine in the dog

The anticancer agent beta-2' deoxythioguanosine (beta-TGdR, NSC-71261) has potential utility for the treatment of hematologic tumors resistant to 6-thioguanine (TG). We have studied the pharmacology and metabolism of these two agents in the beagle dog. [35S] beta-TGdR was administered as an IV bolus to five dogs at a dose of 10 mg/kg. Plasma radioactivity declined biphasically with an average terminal t 1/2 of 3.7 h. Cumulative urinary excretion of the radiolabel 5 h after administration was 19% of the total dose. In another four dogs that received 100 mg/kg (2.71 g), the average terminal plasma t 1/2 was 7.7 h and the 5-h cumulative urinary excretion was 28% of the total dose. [35S]Thioguanine, 5 mg/kg was similarly administered IV to three beagle dogs. The average terminal t 1/2 of [35S]TG and metabolites was 4.6 h, and the 5-h cumulative urinary excretion of the [35S] label was 47%. Similar studies were conducted in three beagle dogs that received the same dose of [8(14)C]TG. In these studies, however, the terminal phase t 1/2 of 14C in plasma was 1.9 h. Cumulative urinary excretion of the 14C was 40% in 5 h. Both TG and beta-TGdR were rapidly and extensively degraded. Neither of these agents and none of their metabolites was found in the cerebrospinal fluid in significant concentrations. In the dog, beta-TGdR was rapidly metabolized to TG and may serve as a slow release form of TG.

Atherosclerosis and dissipative structures

The theory of dissipative structure is applied to the study of atherosclerosis. An autocatalytic theoretical model is suggested. The behaviors of the model are in agreement with the facts of experimental atherosclerosis. We predict the high effectiveness of combinative therapy for atherosclerosis with drugs affecting protein metabolism and lipid metabolism. It was verified by animal experimentation. Further possible developments are briefly discussed. This work is the theoretical foundation of the Multi-Risk Factor Intervention trial (MRFIT) which is popularized clinically in its beginning all over the world.

Effects of endotoxin on the pharmacology of antineoplastic agents

Patients with cancer often develop serious gram-negative bacterial infections. Since bacterial endotoxins have been shown to affect the in vitro hepatic metabolism of antineoplastic agents, significant infection may adversely affect drug pharmacokinetics and metabolism in these patients. To evaluate the clinical significance of these effects, bacterial endotoxin (0.5 mg/kg, IV) was administered to male beagle dogs 1 or 24 h prior to the administration of radiolabeled 5-fluorouracil (5-FU), methotrexate (MTX), arabinosylcytosine (Ara-C), or vinblastine (VLB) as an IV bolus. Drug levels in plasma and urine were measured at various times after administration and standard pharmacokinetic parameters were calculated. The pharmacokinetics of all four agents were found to be significantly altered by the administration of bacterial endotoxin. However, there were no detectable patterns to these changes so that no predictions could be made. In studies on rats, chronic, nonlethal endotoxin administration (0.8 mg . kg-1 . day-1 for 10 days) resulted in a dramatic decrease in the distribution of [14C]methylglyoxal bis(guanylhydrazone) (MGBG) in liver, kidney, intestine, heart and lung tissue. This suggests that bacterial endotoxin may also effect drug pharmacokinetics by altering drug penetration into various organs. In studies on hepatic microsomes isolated from rats, bacterial endotoxin incubation affected aniline hydroxylase activity only at concentrations greater than 0.4 mg/ml, at least tenfold higher than the LD 50 of endotoxin in rats. It therefore seems likely that the endotoxin may require in vivo metabolism to affect changes in drug metabolism and disposition.

The pharmacologic fate of the antitumor agent 2-amino-1,3,4-thiadiazole in the dog

Anticipating the renewed clinical trial of the antitumor agent 2-amino-1,3,4-thiadiazole (AT, NSC-4728), we have studied the pharmacologic fate of AT-5-14C in beagle dogs. The drug was only minimally metabolized in 5 h; the radioactivities in the urine, and particularly in the plasma, resided almost entirely in unchanged AT. In four dogs, after IV administration of AT-5-14C at 10 mg/kg (200 mg/m2), 150-200 muCi per animal, the terminal plasma t1/2 of AT was 13 h, and less than 10% of the administered dose appeared in the urine in 5 h. When the dose was raised to 25 mg/kg (500 mg/m2) in four dogs, the average plasma t1/2 of AT was 10 h; the 5-h cumulative excretion of the agent was 9% of the dose in the urine, 0.3% in the bile, and 0.1% as 14CO2 in the expired air. The average total clearance of AT was 0.70 ml/kg/min. Drug concentrations in the cerebrospinal fluid were 95% of those in the plasma at semi-steady state. At autopsy 5 h after dosing, more than 75% of the administered radioactivity was retained in the body, the highest amounts in terms of micrograms per gram of wet tissue being in the liver, kidney, lung and stomach. No appreciable changes in AT pharmacokinetics were evident upon simultaneous IV administration of allopurinol at 30 or 60 mg/kg. AT was less than 7% bound to dog plasma protein at 25 degrees C in concentrations of 12-100 microgram/ml.

Pharmacological disposition of 1,4-bis (2-[(2-hydroxyethyl)amino]-ethylamino)-9,10-anthracenedione diacetate in the dog

1,4-Bis (2-[(2-hydroxyethyl)amino]ethylamino)-9,10-anthracenedione (NSC 287513) (HAQ) may be selected for clinical trial based on its activity against a number of transplantable rodent tumors. Using a high-pressure liquid chromatograph assay, we have studied the pharmacological fate of HAQ in beagles. After i.v. administration of HAQ at 15 mg/kg (300 mg/sq m), the initial plasma t1/2 of the agent was 9.4 min, and the terminal t1/2 was 115.2 min. A maximal plasma concentration of 24.9 mg of HAQ per liter was attained. A high plasma clearance of 23.5 ml/kg/min was observed in these animals. The extrapolated apparent volume of distribution was 693.7 ml/kg, comparable to that of antipyrine in the dog. In 5 hr, 24.0% of the administered HAQ has been excreted in the urine unchanged, and a trace of a metabolite was detected, amounting to less than 2% of the UV-absorbing (254 nm) materials. However, hepatobiliary excretion constituted the primary route of drug elimination since 39.5% of the dose was found in the bile during the same period. An extraction procedure has been developed to quantify HAQ in tissue homogenates with 75 to 80% recovery. At autopsy, 5 hr after dosing, drug distribution in terms of percentage of the dose administered is as follows: liver, 7%; kidneys, 3.5%; pancreas, 3.1%; small intestine, 1.5%; stomach, 1.3%; spleen, 0.7%; lungs, 0.5%; heart, 0.4%; large intestine, 0.4%; and brain, 0.2%.

Dichloroallyl lawsone

Dichloroallyl lawsone (DCL, NSC-126771), a synthetic analogue of the antimalarial lapachol, is potentially useful in cancer chemotherapy. Unlike most anticancer agents, DCL is not significantly myelosuppressive in animals but it induces acute cardiac toxicity in the rhesus monkey. This cardiac toxicity seems to be correlated with the maximal plasma DCL concentration, about 130 mg/L in the monkey. We have studied DCL pharmacokinetics in patients in an attempt to define safe dose limits for the Phase I clinical trial. After the rapid intravenous infusion of 10 mg/m2 of radioactive [1- or 4-14C]DCL, 250 muCi per patient, the mean peak plasma concentration of unchanged DCL in four patients was 2.9 +/- 0.3 mg/L. The drug had a mean initial plasma half-life of 48.9 +/- 19 min and a terminal half-life of 20.3 +/- 1.8 hr, with a C X t of 50.1 +/- 12 mg/L/hr, and a clearance rate of 0.08 ml/kg/min. These data suggest that in clinical trials the DCL dose given by rapid intravenous infusion should not exceed 450 mg/m2 so that the maximal plasma drug concentration remains below 130 mg/L.

Disposition and metabolism of 1-(tetrahydro-2-furanyl)-5-fluorouracil (ftorafur) in humans

The pharmacology of high-dose 1-(tetrahydro-2-furanyl)-5-fluorouracil (FT) has been studied by radiochemical and chromatographic techniques in eight patients. Plasma disappearance of FT was exponential, with a half-life of 8.8 hr. Plasma concentrations of 5-fluorouracil (FUra) were sustained at 12.8 nmol/ml (1.7 microgram/ml) for at least 48 hr after FT administration. The concentrations of FUra derived from the administration of FT were considerably greater than were those achieved by constant infusion of FUra at the maximal tolerated dose of 1.1 g/sq m without causing unacceptable mucositis. The cumulative urinary excretion was 20% of the administered dose in 24 hr. FT underwent in vivo biotransformation to 2 hydroxytetrahydrofuranyl-5-fluorouracil derivatives in addition to anabolites and catabolites of FUra. High concentrations of FT and FUra were present in the cerebrospinal fluid, which could account for the severe central nervous system toxicity of FT at high doses. We conclude that the antitumor activity of FT is partially attributable to its slow release of FUra.