In vitro metabolism and in vivo pharmacokinetics of quinoline 3-carboxamide derivatives in various species.

The metabolism of a group of quinoline 3-carboxamide derivatives was evaluated in liver microsomes from various species. In addition, metabolism data were compared with in vivo pharmacokinetics in the mouse. The studied compounds were metabolized by cytochrome P450 enzymes. Microsomal clearance was low and seemed independent of a substituent in the quinoline moiety, whereas clearance was enhanced when an ethyl group replaced the methyl group at the carboxamide position. A similar metabolism with hydroxylated and dealkylated metabolites was found in the various species, with quantitative differences due to substituent. As predicted from the in vitro studies, in vivo pharmacokinetics showed low clearance and thus high exposure of the parent compounds in the mouse. The therapeutic effect seen in the acute EAE mouse model for these related compounds seems dependent on the high exposure of parent compound rather than formation of any potentially active metabolites.

Absorption and disposition including enterohepatic circulation of (14C) roquinimex after oral administration to healthy volunteers.

The absorption and disposition of roquinimex (Linomide) were studied in four male and two female healthy volunteers. The subjects received a single oral aqueous solution of 14C-labelled roquinimex, about 0.1 mg/kg, after an overnight fast. Blood samples were taken and urine and faeces were collected for 10 days after dosing. The plasma, urine and faeces concentrations of roquinimex and metabolites were determined by high-performance liquid chromatography (HPLC) with radiochemical detection. The metabolites were identified by HPLC-mass spectroscopy (MS). The plasma concentration-time profiles of roquinimex exhibited a rapid absorption followed by a bi-exponential disposition. A secondary peak was observed between 6 and 8 h, indicating enterohepatic circulation (EHC) of roquinimex. The terminal disposition half-life was estimated as 27 h. The primary metabolic pathways of roquinimex were hydroxylation, demethylation and conjugation. The major compound in plasma was roquinimex; metabolites were only occasionally detected. In urine and faeces, roquinimex accounted for 2% of the dose and conjugated and hydroxylated metabolites each accounted for about 30% of the dose. A model was derived for the plasma concentrations of roquinimex and the amount of urinary excreted roquinimex to take into account EHC. This model improved the goodness-of-fit according to common goodness-of-fit criteria. The values of the pharmacokinetic parameters were similar using compartmental and non-compartmental methods, indicating that the contribution of EHC of roquinimex is of minor importance in the evaluation of the pharmacokinetics of roquinimex.

Identification of cytochrome P4503A as the major subfamily responsible for the metabolism of roquinimex in man.

1. Roquinimex, a novel immunomodulator, is metabolized in liver microsomes from mouse and rat via cytochrome P450s to four hydroxylated and two demethylated metabolites (R1-6). The study investigated which cytochrome P450 enzyme(s) is responsible for the metabolism of roquinimex in man. 2. Enzyme kinetic analysis demonstrated an apparent Km = 1.28-7.00 mM and Vmax = 50-159 pmol x mg(-1) microsomal protein x min(-1) for the primary metabolites in human liver microsomes. The sum of Cl(int) for the primary pathways was 0.167 microl x mg(-1) microsomal protein x min(-1). 3. A correlation between the formation rate of R1-6 and 6beta-hydroxylation of testosterone was obtained within a panel of liver microsomes from 11 individuals (r2 = 0.72-0.97). Furthermore, significant inhibition (>90%) of roquinimex primary metabolism was demonstrated by ketoconazole and troleandomycin, specific inhibitors of CYP3A4 as well as with anti-CYP3A4 antibodies. Moreover, a similar metabolite pattern was produced from roquinimex by incubation with cDNA-expressed CYP3A4 as by human liver microsomes. 4. In conclusion, these data indicate a major role for CYP3A4 in the formation of roquinimex primary metabolites in human liver microsomes.

Pharmacodynamic model of testosterone suppression after intramuscular depot estrogen therapy in prostate cancer.

BACKGROUND: A long-acting parenteral depot estrogen, polyestradiol phosphate (PEP), which has been in clinical use for several years in combination therapy, has been reevaluated pharmacokinetically and clinically as a single treatment. The present report describes a model predicting the effect on testosterone flux achieved with this estrogen drug. METHODS: Data on serum levels of estradiol and testosterone from a single-dose study, in prostate cancer patients as well as data from injections of 240 or 320 mg PEP each fourth week, were used for pharmacokinetic/dynamic modeling. RESULTS: Serum concentrations of estradiol were governed by a flip-flop mechanism when administered as PEP. An indirect-response model fitted to individual data showed a value of about 500 pmol estradiol/l serum to get a 50% suppression of serum testosterone concentrations. CONCLUSIONS: This model could successfully predict the serum levels of estradiol and testosterone after repeated injections at different doses and was also used to simulate the testosterone suppressing effect of a new dose regimen.

Metabolism of roquinimex in mouse and rat: an in vitro/in vivo comparison.

1. In vitro studies with roquinimex, an immuno-modulator, in liver microsomes from mouse and rat were conducted to evaluate the primary metabolism and compare the metabolite pattern as well as the rate of metabolism with the in vivo pharmacokinetics of the compound in these two species. 2. In the presence of NADPH, roquinimex was metabolized to six primary metabolites (R1-6) by liver microsomes from mouse and rat. The formation of these metabolites was qualitatively similar in both species, and was greatly enhanced by pretreatment with PCN, an inducer of cytochrome P4503A. 3. The identification of the R1-6 demonstrated that roquinimex had been hydroxylated and demethylated. Hydroxylation at different sites of the quinoline moiety was the dominating reaction in both species. 4. Comparison of the resulting microsomal intrinsic clearance of 0.3 micromol mg(-1) protein min(-1) in mouse liver microsomes, versus 0.03 micromol mg(-1) protein min(-1) in rat liver microsomes demonstrated that the mouse possesses about a 10-fold greater metabolic capacity for roquinimex than the rat. 5. The in vivo pharmacokinetics of roquinimex demonstrated a 7-fold higher clearance in mouse than in the rat (82 ml h(-1) kg(-1) in mouse, 10.6 ml h(-1) kg(-1) in rat), which is in concordance with the in vitro findings.

Metabolic fate of delmopinol in man after mouth rinsing and after oral administration.

1. The metabolism of delmopinol, an inhibitor of plaque formation and gingivitis. has been studied after mouth rinsing or an oral dose of 14C-delmopinol to healthy male volunteers. The metabolite pattern was studied in urine and plasma samples (unhydrolysed or hydrolysed with conjugate cleaving enzymes) by liquid chromatography (LC) with radio detection. Metabolite identifications were carried out by gas chromatography-electron-impact mass spectrometry (GC-MS) and by liquid chromatography-thermospray mass spectrometry (LC-MS). 2. The metabolic clearance of delmopinol was high, and < 0.2% of the dose was excreted as intact delmopinol in the urine. The main metabolites were, for both administration routes, glucuronide conjugates of delmopinol and of (omega-1-hydroxy) delmopinol. These metabolites were predominant and accounted for nearly the entire urinary radioactivity and most of the plasma radioactivity. After mouth rinsing, parent delmopinol was also one of the main compounds in plasma. 3. Several other products of oxidation of the aliphatic side-chain were present in minor amounts in urine. These metabolites also appeared to be excreted as glucuronic acid conjugates. 4. Glucuronidated (omega-1-hydroxy) delmopinol separated into three peaks by the LC system used. This could be due to different chromatographic properties of conjugate isomers, positional or optical.

Determination of estramustine phosphate and its metabolites estromustine, estramustine, estrone and estradiol in human plasma by liquid chromatography with fluorescence detection and gas chromatography with nitrogen-phosphorus and mass spectrometric detection.

Bioanalytical methods for the determination of estramustine phosphate by liquid chromatography and its four main metabolites estromustine, estramustine, estrone and estradiol by gas chromatography are described. For the estramustine phosphate assay the plasma was purified by protein precipitation followed by a C18 solid-phase extraction. For the metabolite assay the plasma samples were purified by a C18 solid-phase and liquid-liquid extraction procedure and derivatised by silanization. Thereafter, estramustine and estromustine were quantified by gas chromatography with nitrogen-phosphorus detection and estradiol and estrone were quantified by gas chromatography with selected ion monitoring. The methods were validated with respect to linearity, selectivity, precision, accuracy, limit of quantitation, limit of detection, recovery and stability. The limit of quantitation was 2.3 micromol/l for estramustine phosphate, 30 nmol/l for estromustine and estramustine, 12 nmol/l for estrone and 8 nmol/l for estradiol. The results showed good precision and accuracy for estramustine phosphate and the four metabolites. The intermediate precision was 6.2-13.5% (C.V.) and the accuracy was 91.8-103.9%.

Metabolism of tauromustine in liver and lung microsomes from various species.

1. The cytochrome P450 (CYP)-mediated metabolism of tauromustine has been evaluated in liver and lung microsomes from various species. Liver microsomes from rat pretreated with typical CYP inducers, human liver microsomes and cDNA-expressed human CYP enzymes were used to study the enzymatic basis of the metabolism. The further metabolism of the monodemethylated product of tauromustine and that of the denitrosated product were also investigated. 2. The major routes of tauromustine metabolism were demethylation to the alkylating active compound, R2, and denitrosation to the inactive metabolite, M3. The extent of metabolism and the activity of demethylation versus denitrosation varied among the species. The highest metabolism was found in mouse (BDF strain) followed by dog, rat and the human liver. Tauromustine was also metabolized to a low extent in lung microsomes from these species. 3. The further metabolism of R2 and M3 was approximately 100 times lower in activity than that of tauromustine. Both the demethylation and the denitrosation of tauromustine were increased 3-fold in liver microsomes from rat pretreated with phenobarbital, whereas treatment with cyanopregnenolone enhanced the denitrosation 11-fold, indicating the involvement of CYP3A. 4. Metabolism across a panel of 10 human liver microsomal samples demonstrated a correlation with testosterone 6beta-hydroxylation of demethylation (r2 = 0.86) and denitrosation of tauromustine (r2 = 0.79). Among the human cDNA expressed CYP enzymes, not only was tauromustine determined to be catalysed predominantly by CYP3A4, but also to some extent by CYP2C19 and CYP2D6. 5. In conclusion, the present results indicate a major role of CYP3A enzymes in the metabolism of tauromustine.

Time for revival of estrogens in the treatment of advanced prostatic carcinoma? Pharmacokinetics, and endocrine and clinical effects, of a parenteral estrogen regimen.

BACKGROUND: The present pilot study tested the clinical performance of a new pharmacokinetically guided dosing regimen of parenteral estrogen in patients with advanced prostatic carcinoma. The aim was to accelerate endocrine effects and to avoid cardiovascular side effects. METHODS: Seventeen patients were randomized to intramuscular injections of 240 mg polyestradiol phosphate (PEP) every second week for the first 8 weeks (five doses), followed by a maintenance dose of 240 mg every month; and 16 patients were randomized to bilateral orchidectomy. The estrogen dosing was calculated by pharmacokinetic modelling to achieve a rapid increase in serum estradiol and thereby a fast decrease in testosterone. RESULTS: The predicted increment in serum estrogen was achieved, together with a subsequent decrease in testosterone in the PEP group. In addition, there were no signs of an increased cardiovascular morbidity. This was probably due to a minimal estrogenic influence on the liver and was reflected by unchanged levels of coagulation factor VII. Clinical effects, during the first 2 years of treatment, were similar in the two treatment arms, with 12 patients in the orchidectomy group and 14 patients in the PEP group responding to treatment. CONCLUSIONS: The present parenteral regimen is an efficient and time-saving estrogen regimen with a favorable side-effect profile. PEP seems to offer a potential for revival of the most cost-effective endocrine treatment of cancer of the prostate, i.e., estrogen.

Dissolution rate-limited absorption and complete bioavailability of roquinimex in man.

In order to investigate the bioavailability and the rate-limiting step of the absorption of roquinimex, an oral solution and a tablet formulation (Linomide(R)) were given to healthy volunteers. The study was conducted as a randomized three-period crossover study in seven male and seven female healthy volunteers. The subjects received an intravenous infusion, an oral solution and an oral tablet formulation, each of 5 mg (about 0.07 mg kg(-1)), as single doses after an overnight fast on three occasions, with a wash-out period of 3 weeks in between. Venous blood samples were taken over 7 days and the plasma concentrations of roquinimex were determined by high-performance liquid chromatography (HPLC) with ultraviolet (UV)-detection. The pharmacokinetics of roquinimex was characterized by a low plasma clearance, 4.9 mL h(-1) kg(-1) and a small volume of distribution, 0.22 L kg(-1). The oral bioavailability of the drug was complete for both the solution and the tablet formulation. The absorption rate was faster for the solution than for the tablet. The disposition of roquinimex was biphasic, with a terminal disposition half-life of 32 h. Between 4 and 8 hours after dosing, a secondary plasma peak was observed, indicating enterohepatic circulation of the drug. No major sex differences were shown in the pharmacokinetics of roquinimex. In conclusion, dissolution rate-limited absorption of roquinimex was shown, which demonstrates that disintegration and dissolution of the tablet play a major role in the absorption process of roquinimex. Despite the delayed absorption after administration of the tablet, the extent of absorption was complete.

Differential uptake of estramustine phosphate metabolites and its correlation with the levels of estramustine binding protein in prostate tumor tissue.

Estracyt (EMP) has been used for the treatment of hormone refractory prostate cancer for many years. Recently, new data from combination studies have given rise to new interest in this old drug. Explanations for the synergy found in the clinic are many, but one major factor may be the previous indication that the drug accumulates in the prostate tumor. We have, therefore, examined the level of the four metabolites, estromustine (EoM), estramustine (EaM), estrone, and estradiol in the tumor and serum of 14 patients with T2 and T3 prostate cancer receiving a single i.v. dose of 600 mg of EMP, about 12 h before radical prostatectomy. Because it has been suggested that the uptake into the prostate tumor is due to binding to the estramustine binding protein (EMBP), we have in addition measured the level of EMBP in the prostate tumor tissue. The main serum and tissue metabolite in all patients was EoM followed by EaM, estrone, and estradiol. The levels for EoM ranged from 63.8-162.8 ng/ml in the serum and from 64.8-1209 ng/ml in the prostate tumor, resulting in a mean ratio for serum to tumor of 1:5. The levels for EaM ranged from 8.3-51.4 ng/ml in the serum and 73.9-563.4 ng/ml in the tumor, giving a mean ratio for serum to tumor of 1:13. The levels of EMBP were higher in T3 tumors than in T2 tumors, 54.1 and 40.7 ng/g tissue, respectively. A significant correlation was found between the levels of EaM (r = 0.60) and the levels of EMBP in the tumor. These data demonstrate that 12 h after a single i.v. dose of 600 mg of EMP the levels of the cytotoxic metabolites EoM and EaM are substantially higher in the tumor than in the serum of the same patient and that a correlation exists between the levels of EaM in the tumor and the levels of EMBP. Thus, this supports the hypothesis that the EMBP is responsible for the retention of EoM and EaM in the prostate tumor.

Apoptotic tumor cell death induced by estramustine in patients with malignant glioma.

Estramustine phosphate (EMP), a cytotoxic drug used in the treatment of prostatic carcinoma, is metabolized and exerts specific cytotoxic effects in malignant glioma in vitro and in vivo. In the present study, we have evaluated the cytotoxic effect of EMP in the clinical situation with regard to appearance of DNA damage and its correlation to the uptake of estramustine (EaM) in human malignant astrocytoma tissue. Ten patients were given 280 mg of EMP p.o. 12 h before surgery. Specimens from brain tumor tissue were collected during surgery and used for detection of fragmented DNA, a hallmark of apoptosis, with in situ end labeling (ISEL) and agarose gel techniques. The main metabolite of EMP in glioma tissue, EaM, was analyzed with gas chromatography. It was demonstrated that EMP induced clusters of ISEL-positive tumor cells and fragmentation of DNA on agarose gels in patients treated with EMP. In the same patients, a significant uptake of EaM in tumor tissue was demonstrated. In control patients, who were not treated with EMP, and in two EMP-treated patients with no uptake of EaM, no signs of fragmented DNA and only a few scattered ISEL-positive cells were seen in the tumor tissue. Signs of apoptosis were also seen in two different experimental models, i.e., in vitro cell cultures of rat glioma cells and an in vivo rat glioma model. It is suggested that EaM can induce apoptosis by a direct effect on a subpopulation of glioma cells in human brain tumors in the clinical situation.

Distribution of estramustine in the BT4C rat glioma model.

Estramustine (EaM), a carbamate ester of 17beta-estradiol and nor-nitrogen mustard, is a cytotoxic compound with antitumoral effect in malignant glioma in vitro and in vivo . However, knowledge of the pharmacokinetics of EaM in experimental glioma is limited. The objective of this study was therefore to investigate further the distribution of EaM in the BT4C rat glioma model. Assessment of EaM uptake and distribution was performed by quantitative whole-body autoradiography. In addition, the uptake of EaM and its metabolites estromustine (EoM), estradiol, and estrone were analyzed by gas chromatography. EaM was taken up from the circulation and was found to be the main product in glioma tissue. Whole-body autoradiography after [14C]-EaM administration revealed a strong 14C label simultaneously in tumor and normal brain tissue at 0.5 h after drug administration. In tumor tissue, sustained high levels of 14C label were detected at 12 h after drug administration. In contrast to the tumor, radioactivity in normal brain tissue rapidly leveled off, indicating a retention of radioactivity in the tumor. The tumor/brain radioactivity ratio reached a peak of 4.5 at 12 h after drug administration. High levels of 14C label were also found in pulmonary tissue. By gas chromatography, EoM was found to be the main metabolite in plasma. However, EaM reached higher levels in tumor tissue, with the mean tumor/plasma ratio being 11.7 as compared with 2.0 for EoM. Only low plasma levels of the estrogen metabolites were detected. In conclusion, EaM is taken up in the BT4C rat glioma tissue and is retained in the tumor as compared with normal brain tissue and plasma. EaM showed a greater selectivity for tumor tissue, exhibiting a high tumor/plasma ratio as compared with EoM. The distribution pattern after administration of EaM, as evaluated by both whole-body autoradiography and gas chromatography, supports the earlier suggestion that the uptake is related to a protein with EaM-binding characteristics.

Pharmacokinetics of 14C-delmopinol in the healthy male volunteer.

1. The absorption and excretion of delmopinol, an inhibitor of plaque formation and gingivitis, were studied in healthy male volunteers. Each subject received a single dose of a 10-ml aqueous solution of 14C-delmopinol at 2 mg/ml as a 1-min mouth rinse (the intended route of administration; n=6) or as an oral dose (n=6). 2. After mouth rinsing, 72% of the dose was expectorated. The retained portion of the dose was rapidly absorbed and eliminated. Of the dose, 25% was recovered in the urine. Renal excretion was predominant also after oral administration with 92% of the dose excreted in the urine. The total recovery of 14C-activity after 6 days was 99% (rinsing) and 95% (oral) with the bulk, 20% (rinsing) and 80% (oral), of the dose excreted already within 8 h. 3. Peak plasma levels of 14C-labelled compounds were attained at 1.5 h after rinsing and 0.5 h after oral administration; total concentrations were approximately 200 and 3000nmol/l, respectively. For parent delmopinol, peak plasma levels of 49 nmol/l (rinsing) and 8 nmol/l (oral) occurred after 1.5 and 1.3 h, respectively. After rinsing, the concentration of delmopinol declined with a half-life of 2.4 h. The plasma level of 14C-labelled compounds declined multiphasically. In the terminal elimination phase (after 72 h) remaining radioactivity, < 2% of dose (rinse) and < 5% of dose (oral), decreased with a half-life of approximately 130 and 160 h, respectively. 4. Results indicate a very low bioavailability (1-3%) due to extensive first-pass metabolism of delmopinol after oral administration. A high plasma clearance (> 60 l/h) and a large volume of distribution (> 200 l) were also indicated. 5. The results of rapid and almost complete recovery in the urine support that delmopinol can safely be used in the treatment of patients with plaque or gingivitis.

Possible bone-preserving capacity of high-dose intramuscular depot estrogen as compared to orchidectomy in the treatment of patients with prostatic carcinoma.

BACKGROUND: Treatment of prostatic disease with GnRH agonists or by orchidectomy affects bone mass negatively. Estrogen treatment has beneficial effects on bone mass in women and might hypothetically have a bone preserving capacity also in patients with prostatic cancer. METHODS: We followed serum markers for bone and collagen metabolism and sex steroids for 18 months in patients with prostatic cancer treated by orchidectomy (N = 13) or by single-drug parenteral polyestradiol phosphate (240 mg intramuscularly every second week for the first two months, and then every fourth week; N = 17). RESULTS: Total and free testosterone reached castration levels within 1.5 months of estrogen treatment. Four patients developing progressive disease and/or signs of metastasis were excluded from the analysis. In the remaining patients, serum osteocalcin, procollagen IIIP (PIIINP), procollagen (PICP), and the crosslinked carboxyterminal telopeptide of type I collagen (ICTP) increased significantly over time following orchidectomy (N = 11). Serum osteocalcin and PICP decreased significantly over time during estrogen treatment (N = 15). Treatment values of all four markers were significantly lower in estrogen-treated than in orchidectomized patients. CONCLUSIONS: The changes in serum bone and collagen markers indicate an increased bone turnover in orchidectomized subjects. The opposite pattern was found in the estrogen-treated patients, indicating a reduced turnover. Estrogens may also have a bone mass-preserving capacity in elderly males with prostatic cancer.

Superantigen-based immunotherapy: a phase I trial of PNU-214565, a monoclonal antibody-staphylococcal enterotoxin A recombinant fusion protein, in advanced pancreatic and colorectal cancer.

PURPOSE: To establish the maximum-tolerated dose (MTD) and define the toxicities of a single-dose infusion of PNU-214565, a recombinant Escherichia coli-derived fusion protein of Staphylococcal enterotoxin A (SEA) and the Fab-fragment of the C242 monoclonal antibody in patients with advanced colorectal and pancreatic carcinomas. To investigate the capability of PNU-214565 to induce a superantigen (SAg) response resulting in cytokine production and tumor regression. PATIENTS AND METHODS: Twenty-one patients (age range, 39 to 76 years; median, 64; 12 men, nine women; 18 colorectal, three pancreatic cancers) were treated with a single 3-hour infusion of PNU-214565, with doses ranging from 0.01 to 1.5 ng/kg. All patients had prior chemotherapy and a good performance status Eastern Cooperative Oncology Group [ECOG] performance status [PS] = 0 [n = 10]; PS = 1 [n = 11]), 10 had prior radiation, and 18 had prior surgery. RESULTS: Fever and hypotension were the most common toxicities. Fever of any grade occurred in 16 of 21 patients (76%): four of 21 (19%) with grade 2 and two of 21 (9.5%) with grade 3. Hypotension of any grade occurred in 13 of 21 (62%): four of 21 with grade 2 and one of 21 (5%) with grade 3. Interleukin-2 (IL-2) and tumor necrosis factor alpha (TNF alpha) induction correlated with toxicity. In the two patients with grade 3 fever, peak IL-2 and TNF alpha levels were 2.9 IU/mL and 165 pg/mL, and 8.3 IU/mL and 245 pg/mL, respectively. Transient, > or = 50% decreases in circulating monocytes were observed in 17 of 21 patients as early as 0.5 hours (median time, 2 hours) from the start of infusion. Decreases (mean 33%) in circulating lymphocytes were observed in seven of 21 patients. All three patients with grade 3 toxicity were treated at the 0.5-ng/kg dose. The significance of baseline anti-SEA, human antimouse antibody (HAMA), CA242-soluble antigen levels, and T-cell receptor variable beta region (TCR V beta) subsets and histocompatibility leukocyte antigen-DR (HLA-DR) genotypes was assessed as possible predictors of toxicity. All toxicities were transient and easily managed. No grade 3 toxicity occurred at the higher dose levels. CONCLUSION: PNU-214565, a SAg-based tumor targeted therapy, is safe when given as a single 3-hour infusion at doses up to 1.5 ng/kg. The MTD for a single dose was not determined. The safety of a repeated dose schedule is currently under investigation, beginning with doses determined to be safe in this trial.

The first clinical pilot study of roquinimex (Linomide) in cancer patients with special focus on immunological effects.

Roquinimex (Linomide) has been demonstrated to suppress tumor growth in animal models. The effect is at least in part related to enhanced numbers and activity of natural killer (NK) cells. In this clinical pilot study, roquinimex was given at increasing doses (0.05 mg/kg to 0.6 mg/kg) to 13 patients (performance status 0-3) with various malignant disorders. Immunology parameters were followed and side effects were observed during the study. The plasma pharmacokinetics of roquinimex was studied at the 0.2 mg/kg dose level. The clinical side effects were dominated by musculoskeletal discomfort, nausea, and pain. No significant hematological or biochemical toxicity was observed. Pharmacokinetic analysis at the 0.2 mg/kg dose level revealed a Cmax of 4.0 mumol/L at tmax of 1.2 hr and an elimination half-life of 42 hr. Increased numbers of phenotypic NK cells, activated T (DR+CD4+) cells, and monocytes were observed after administration of roquinimex compared with pretreatment values. Roquinimex seems to be an active immunomodulator with manageable toxicity. Further exploration of therapeutic efficacy is warranted.

Pharmacokinetics and testosterone suppression of a single dose of polyestradiol phosphate (Estradurin) in prostatic cancer patients.

The pharmacokinetics and endocrine effects of polyestradiol phosphate (PEP; Estradurin) were studied by determination of the concentrations of estradiol (E2), unconjugated (E1) and total estrone (tE1; > or = 85% estrone sulfate), and testosterone in serum from 11 prostatic cancer patients after administration of a single intramuscular injection (320 mg). After injection of PEP, serum concentrations of E2, E1, and tE1 increased during 2-3 weeks. Thereafter serum E2 declined monophasically with a mean half-life of 70 days. The elimination of E1 and tE1 seemed to be governed by the formation of E2. The testosterone concentration decreased inversely to the raising E2 level and reached castration levels within 3 weeks and remained at this level for about 2 weeks, whereafter it increased inversely to the decreasing E2 concentrations.

Chromosome aberrations and pharmacokinetics in patients receiving tauromustine as either a single or a repeated dose.

Tauromustine (TCNU) is an exploratory drug that has demonstrated activity in various solid tumors. We examined chromosome aberrations and plasma levels of the drug in two groups of patients receiving either a single dose of 130 mg/m2 or 40 mg/m2 on 3 consecutive days. Peak plasma concentrations (mean +/- SD) were obtained at a similar time after both treatments, i.e., at 38 +/- 25, 32 +/- 24, 28 +/- 14, and 40 +/- 26 min after administration of 130 mg/m2 on day 1 and after that of 40 mg/m2 on days 1, 2, and 3, respectively. In addition, the cumulative area under the curve (AUC value) determined after administration of 40 mg/m2 x 3 was similar to that noted after treatment with a single dose of 130 mg/m2, i.e., 180 and 179 micrograms min ml-1, respectively. Both treatments induced chromosome aberrations (CAs) in peripheral blood lymphocytes. A dose-dependent increase in the number of CAs was found, with 40 mg/m2 producing 5.5% CAs and 130 mg/m2 yielding 20.9% CAs at 24 h after treatment. In addition, although the drug concentration declined to a level under the detection limit between the daily treatments, drug-induced chromosome damage was cumulative, with the 90-min values increasing from 4.8% on day 1 to 14.3% CAs on day 3. In individual patients, no correlation was found between CAs and kinetic parameters; however, the total mean CA yield was in agreement with the total drug exposure (CAs, 14.3% and 14.6%, AUC 180 +/- 62.8 and 179 +/- 115 micrograms min ml-1, respectively.

The effect of different dose levels of degradable starch microspheres (Spherex) on the distribution of a cytotoxic drug after regional administration to tumour-bearing rats.

Tumour uptake of a radiolabelled anticancer drug, tauromustine ([14C]TCNU), was investigated, using two different routes of administration in rats with colon adenocarcinomas implanted in the liver. Intra-arterial administration produced higher concentrations of the drug and/or its metabolites in tumour tissue and lower concentrations in normal tissue compared to intravenous administration. The investigation of co-injection of [14C]TCNU intra-arterially with degradable starch microspheres (DSM) indicated that a high dose of DSM (30 mg/kg) resulted in a high concentration of radioactivity in normal liver tissue, and in adjacent organs. This unfavourable pattern was not observed with the low dose of DSM (12.5 mg/kg), which produced a significant increase in tumour uptake. The results demonstrate the efficacy of partial vascular blockade, as elicited by the low dose of DSM. This regime caused [14C]TCNU to be preferentially retained in the active peripheral regions of the tumour.