Daunorubicin metabolism in acute nonlymphocytic leukemia

Immobilization-Free Determination of Dissociation Constants Independent of Ligand Size Using MicroScale Thermophoresis

The quantitative characterization of aptamer-ligand interactions is an important step in the aptamer development process. However, certain pitfalls impede K_D determination, especially when working with small molecule ligands. These include altered binding behavior caused by ligand immobilization. Further, the compulsory requirement for major differences in size between the bound and unbound state makes small molecule ligands ineligible for separation-based methods. MicroScale Thermophoresis circumvents such limitations as binding is accurately quantified with both binding partners free in solution and independent of ligand size. In this chapter, we present a protocol for the characterization of a DNA aptamer binding to its small molecule ligand daunorubicin.

The pharmacokinetics of therapeutic arsenic trioxide in acute promyelocytic leukemia patients

Arsenic trioxide (ATO) treats Acute Promyelocytic Leukemia (APL). ATO is converted from inorganic arsenic (iAs) to methylated (MAs) and dimethylated (DMAs) metabolites, which are excreted in the urine. Methylation of iAs is important in detoxification, as iAs exposure is deleterious to health. We examined ATO metabolism in 25 APL patients, measuring iAs, MAs, and DMAs. Plasma total iAs increased after ATO administration, followed by a rapid decline, reaching trough levels by 4-6 h. We identified two patterns of iAs metabolism between 6 and 24 h after infusion: in Group 1, iAs increased and were slowly converted to MAs and DMAs, whereas in Group 2, iAs was rapidly metabolized. These patterns were associated with smoking and different treatments: ATO with all-trans retinoic acid (ATRA) alone vs. ATO preceded by ATRA and chemotherapy. Our data suggest that smoking and prior chemotherapy exposure may be associated with ATO metabolism stimulation, thus lowering the effective blood ATO dose.

Genomics and pharmacogenomics of pediatric acute lymphoblastic leukemia

Acute lymphoblastic leukaemia (ALL) is a prevalent form of pediatric cancer that accounts for 70-80% of all leukemias. Genome-based analysis, exome sequencing, transcriptomics and proteomics have provided insight into genetic classification of ALL and helped identify novel subtypes of the disease. B and T cell-based ALL are two well-characterized genomic subtypes, significantly marked by bone marrow disorders, along with mutations in trisomy 21 and T53. The other ALLs include Early T-cell precursor ALL, Philadelphia chromosome-like ALL, Down syndrome-associated ALL and Relapsed ALL. Chromosomal number forms a basis of classification, such as, hypodiploid ALL, near-haploid, low-hypodiploid, high-hypodiploid and hypodiploid-ALL. Advances in therapies targeting ALL have been noteworthy, with significant pre-clinical and clinical studies on drug pharmacokinetics and pharmacodynamics. Methotrexate and 6-mercaptopurine are leading drugs with best demonstrated efficacies against childhood ALL. The drugs in combination, following dose titration, have also been used for maintenance therapy. Methotrexate-polyglutamate is a key metabolite that specifically targets the disease pathogenesis, and 6-thioguanine nucleotides, derived from 6-mercaptopurine, impede replication and transcription processes, inducing cytotoxicity. Additionally, glucocorticoids, asparaginase, anthracycline, vincristine and cytarabine that trans-repress gene expression, deprives cells of asparagine, triggers cell cycle arrest, influences cytochrome-P450 polymorphism and inhibits DNA polymerase, respectively, have been used in chemotherapy in ALL patients. Overall, this review covers the progress in genome technology related to different sub-types of ALL and pharmacokinetics and pharmacodynamics of its medications. It also enlightens adverse effects of current drugs, and emphasizes the necessity of genome-wide association studies for restricting childhood ALL.

Pharmacogenomics in pediatric leukemia

PURPOSE OF REVIEW

The therapeutic index of many medications, especially in children, is very narrow with substantial risk for toxicity at doses required for therapeutic effects. This is particularly relevant to cancer chemotherapy, when the risk of toxicity must be balanced against potential suboptimal (low) systemic exposure that can be less effective in patients with higher rates of drug clearance. The purpose of this review is to discuss genetic factors that lead to interpatient differences in the pharmacokinetics and pharmacodynamics of these medications.

RECENT FINDINGS

Genome-wide agonistic studies of pediatric patient populations are revealing genome variations that may affect susceptibility to specific diseases and that influence the pharmacokinetic and pharmacodynamic characteristics of medications. Several genetic factors with relatively small effect may be combined in the determination of a pharmacogenomic phenotype and considering these polygenic models may be mandatory in order to predict the related drug response phenotypes. These findings have potential to yield new insights into disease pathogenesis, and lead to molecular diagnostics that can be used to optimize the treatment of childhood cancers.

SUMMARY

Advances in genome technology, and their comprehensive and systematic deployment to elucidate the genomic basis of interpatient differences in drug response and disease risk, hold great promise to ultimately enhance the efficacy and reduce the toxicity of drug therapy in children.

Spectrophotometric Determination of Anthracycline Anticancer Agents with Aluminum(III) and Chromazurol S in a Nonionic Surfactant Micellar Medium

A simple and highly sensitive spectrophotometric method for the determination of anthracycline anticancer agents, such as Daunorubicin hydrochloride (DAU), was established by using aluminum(III) and Chromazurol S (CAS) in a nonionic surfactant micellar medium. In the case of determination of DAU, the apparent molar absorptivity was 1.3 x 10(5) dm3 mol(-1) cm(-1) at 615 nm. Beer's law was obeyed in the concentration range of 0.028 - 2.82 microg ml(-1) for DAU. Owing to no need for solvent extraction, this method could be applied to assays of DAU and related drugs in pharmaceutical preparations.

Disposition of liposomal daunorubicin during cotreatment with cytarabine in patients with leukaemia

OBJECTIVE

To investigate the pharmacokinetics and pharmacodynamics of liposomal daunorubicin (DaunoXome) 80 or 100 mg/m(2) on days 1, 2 and 3 coadministered with standard or high-dose cytarabine to patients with poor-risk acute leukaemia.

DESIGN

Unblinded pharmacokinetic-pharmacodynamic study.

PARTICIPANTS

Twenty-three adult patients with acute leukaemia.

METHODS

Blood, bone marrow and urine samples were collected at appropriate intervals on days 1-6. Total daunorubicin and daunorubicinol concentrations in plasma, bone marrow, peripheral blood cells and urine were measured by high performance liquid chromatography.

RESULTS

Liposomal daunorubicin exhibited a markedly different pharmacokinetic behaviour from the free drug due to a slow distribution of the liposomal moiety into the body. The ratio of area under the concentration-time curve (AUC) for metabolite to parent drug was lower for liposomal daunorubicin than for free daunorubicin, mainly due to higher concentrations of the parent drug in plasma, whereas daunorubicinol exposure was more or less comparable, if not higher. After liposomal daunorubicin at both 80 and 100 mg/m(2), total daunorubicin concentrations in leukaemic cells were at least similar to those observed for free daunorubicin, and significant accumulation was also observed in bone marrow blast cells. Nineteen of 23 patients obtained a complete remission, although 13 had P-glycoprotein-overexpressing blast cells. Grade 3-4 mucositis was found only in three patients with very high AUCs for total daunorubicin and daunorubicinol.

CONCLUSIONS

Liposomal daunorubicin at both 80 and 100 mg/m(2) in combination with cytarabine may represent a valid treatment for high-risk acute leukaemia. Liposomal daunorubicin may be helpful in overcoming multidrug resistance, since it shows significant accumulation into tumour target cells, irrespective of P-glycoprotein expression. The tolerability profile suggests that toxicity may be related to exposure to both the parent drug and the metabolite.

Determination of anthracycline antibiotics doxorubicin and daunorubicin by capillary electrophoresis with UV absorption detection

Sweeping preconcentration and electrokinetic injection was used for the capillary electrophoretic analysis of trace amounts of biologically active anthracyclines with UV absorption detection. Phosphate buffer (100 mM), pH 2.5, with addition of 40% v/v methanol was used as background electrolyte (BGE). Sodium dodecyl sulfate (150 mM) was added to BGE in the inlet vial as the sweeping agent. The system enables effective separation of anthracyclines as well as cleanup from matrix impurities. Sweeping preconcentration of sample provides an excellent detection limit (1 x 10(-9) mol L(-1)). The method was applied for the determination of therapeutic levels of doxorubicin in real plasma samples.

Carbonyl reduction of daunorubicin in rabbit liver and heart

A major problem of anthracycline anticancer treatment are the cardiotoxic side effects associated with drug therapy. Increased attention has recently been focused on the 13-hydroxy anthracycline metabolites which are formed by carbonyl reduction of the parent drug as contributing to cardiotoxicity. By using daunorubicin as a reference molecule, our study was designed to quantitatively evaluate and compare the extent of anthracycline carbonyl reduction of liver and heart at the physiological important pH 7.4, and to identify the enzyme(s) involved under these conditions. The present kinetic data indicate that only one single enzyme system is active in cytosol of both tissues. According to its specific inhibition by quercitrin and the failure of a barbiturate to affect activity the enzyme responsible for daunorubicin carbonyl reduction in these fractions is carbonyl reductase (EC 1.1.1.184). Since the KM values differ significantly from each other, it is suggested that liver and heart express different isoforms of this enzyme. We failed to detect any specific daunorubicin carbonyl reductase activity in both microsomal fractions. Intrinsic clearance values revealed that liver has obviously 350-times the capacity of total 13-hydroxy metabolite formation compared to heart. This indicates that under a therapeutic regimen 13-hydroxy anthracyclines of hepatic origin would add to the metabolites that are produced by the heart itself. The prevention of these metabolites may represent a potential approach for enhancing the safety and efficacy of anthracycline chemotherapy.

Induction of daunorubicin carbonyl reducing enzymes by daunorubicin in sensitive and resistant pancreas carcinoma cells

Daunorubicin (DRC) and other anthracyclines are valuable cytotoxic agents in the clinical treatment of certain malignancies. However, as is the case with virtually all anticancer drugs, tumor cell resistance to these agents is one of the major obstacles to successful chemotherapy. In addition to an increased energy-dependent efflux of chemotherapeutic agents, enzymatic drug-inactivating mechanisms also contribute to multidrug resistance of tumor cells. In the case of DRC, carbonyl reduction leads to 13-hydroxydaunorubicinol (DRCOL), the major metabolite of DRC with a significantly lower antineoplastic potency compared to the parent drug. In the present study, we compared two pancreas carcinoma cell lines (a DRC-sensitive parental line and its DRC-resistant subline) with respect to their capacity of DRC inactivation via carbonyl reduction. In addition, we cultured the two cell lines in the presence of increasing sublethal concentrations of DRC. Evidence is presented that DRC treatment itself leads to a concentration-dependent induction of DRC carbonyl reduction in subcellular fractions of both the sensitive and resistant pancreas carcinoma cells, resulting, surprisingly, in different susceptibilities to DRC. The principal difference between the two cell lines becomes most apparent at high-dose DRC supplementation (1 microgram/mL), at which DRC resistant cells exhibited higher inducibility of DRC-inactivating enzymes, whereas respective sensitive cells already showed an impairment of cellular viability. The use of the diagnostic model substrates metyrapone and p-nitrobenzaldehyde reveals that this adaptive enhancement of DRC inactivation can be attributed to the induction of DRC carbonyl reductases different from known aldehyde and carbonyl reductases. In conclusion, these findings suggest that inactivation of anthracyclines by carbonyl reduction is inducible by the substrate itself, a fact that might be considered as one of the enzymatic mechanisms that contribute to the acquired resistance to these drugs.

Phase I and pharmacologic study of liposomal daunorubicin (DaunoXome)

We have completed a phase I and pharmacology study of liposomally-encapsulated daunorubicin (DaunoXome). Of 32 patients entered, 30 were evaluable. No toxicity was encountered at the initial dose-escalation steps from 10 to 60 mg/m2. At 80 mg/m2, two patients manifested grade 2 neutropenia. At least grade 3 neutropenia occurred in all patients receiving 120 mg/m2. Alopecia and subjective intolerance were mild. Cardiotoxicity was not observed except for an episode of arrhythmia in a patient with lung cancer and prior radiation. Only one minor objective response was observed in this population of refractory solid tumors. Pharmacokinetics differed from those of the free drug with no detection of daunorubicinol. We recommend future phase II studies with a dose of 100 mg/m2 in previously treated and 120 mg/m2 of DaunoXome in previously untreated patients with solid tumors.

Anthracycline and anthraquinone anticancer agents: current status and recent developments

The clinical treatment of neoplastic diseases relies on the complementary procedures of surgery, radiation treatment, immunotherapy and chemotherapy. The latter technique has matured from its earliest applications of mustard alkylating agents in the 1940s to an increasingly rationally based discipline, which is contributing significantly to the management of human malignancies. As the field of chemotherapy matured, several promising natural anticancer agents were identified. However, a more urgent need soon arose from the common experience of clinically limiting toxicities of most anticancer drugs, i.e. the necessity to develop less toxic clinical drug candidates. Thus, the medicinal chemist turned towards analog development involving certain anthraquinones. Hand-in-hand with this considerable synthetic effort, which uncovered several promising clinical leads, biochemical pharmacology, or study of the mechanisms of action of clinical anticancer agents, afforded deeper insight into drug metabolism and mode of action. More recently, therefore, the field of synthetic organic chemistry, which has been complemented by the methods of microbial chemistry, has been faced with new synthetic challenges, occasioned by the identification of hitherto unrecognized cellular targets for anticancer drugs, such as topoisomerases and helicases. The armementarium of the oncologist currently includes about 40-50 clinically useful chemical agents. The paradigm of cytotoxic anticancer agents is doxorubicin, an anthracycline, which is still amongst the most widely prescribed and effective of anticancer agents. The review attempts to summarize the discovery of anthracyclines and the elucidation of their several mechanisms of action and efforts towards improvement of their therapeutic efficacy.

Use of plasma cytotoxic activity to model cytotoxic pharmacodynamics of anticancer drugs

We have developed a pharmacokinetic/pharmacodynamic approach that integrates the disposition, cytotoxic activity and interaction of anticancer drugs. Fundamental to this approach is the measurement of the cytotoxicity, against a "target" cell line, of patient plasma collected at different times after administration of the anticancer agent(s). To illustrate this approach, we have studied the plasma cytotoxic activity (PCA), against HL-60 cells, of plasma from 11 acute myeloblastic leukemic patients treated with daunorubicin (DNR). Plasma, obtained before and serially for 24 h after DNR treatment, was assayed by HPLC for DNR and daunorubicinol (DNRol), its active metabolite. The corresponding observed PCA values (PCAobs) against HL-60 cells were also measured with a flow-cytometric cell-survival assay that we had developed previously. The pharmacodynamics, i.e. PCA, were co-modeled (dual Hill equation with an interaction term to allow synergism or antagonism) with the pharmacokinetics. The integration of the PCA profile provided the area under the observed PCA versus time curve (AUCobs). For each patient, we also generated an "interaction panel", by adding known amounts of DNR and DNRol to his or her pretreatment plasma. The corresponding cytotoxicities were measured, and then applied to the pharmacodynamic model. This provided a standard surface from which the PCA of each sample obtained after therapy was predicted (PCAprd), on the basis of assayed concentrations of DNR and DNRol in that sample. For plasma samples obtained after treatment, the model simultaneously fit all three outputs, i.e. PCA and DNR/DNRol concentration, very well. We observed substantial interpatient variability in HL-60 growth rate in medium containing patient pretreatment plasma, in DNR activity in pretreatment plasma, and in the in vitro activity (PCA) of plasma obtained after DNR treatment. We also compared the AUCprd to the AUCobs for each patient, and we identified a subset of 4/11 acute myeloblastic leukemic patients who had developed much more PCA after DNR administration that could be explained by the measured concentrations of DNR and DNRol. This may be due to unidentified active metabolites or to factors produced in the plasma in response to the treatment. This pharmacokinetic/pharmacodynamic model is promising to describe pharmacodynamics and interactions of anticancer drugs in cancer patients.

Pharmacokinetics of idarubicin (4-demethoxydaunorubicin; IMI-30; NSC 256439) following intravenous and oral administration in patients with advanced cancer

The plasma pharmacokinetics of idarubicin (4-demethoxydaunorubicin) were studied in 20 patients with advanced malignant disease after intravenous (21 occasions) and oral (14 occasions) administration. Idarubicin plasma concentrations were measured by high performance liquid chromatography with fluorescence detection. Pharmacokinetic parameters calculated for the intravenous plasma drug concentration, time data revealed a terminal half-life of 12.9 +/- 6.0 h (mean +/- s.d.), clearance 98.7 +/- 47.3 1 h-1 m-2 and volume of distribution 1533 +/- 536 1 m-2. A bi-exponential equation corresponding to a two compartment open model best fitted the data. Half-life and clearance were not significantly different following oral administration. Bioavailability of oral idarubicin was 0.29 +/- 0.20 (mean +/- s.d.). There was a wide range of bioavailability between and within subjects. Plasma concentrations of idarubicinol (the only metabolite detected) rapidly exceeded those of the parent drug, and exposure to this metabolite was greater than to the parent drug. The mean half-life of idarubicinol was not significantly different after i.v. (63.1 +/- 28.2 h) and oral (45.8 +/- 16.0 h) administration. Much larger amounts of this metabolite were formed following the oral route of administration. This may have implications for the clinical use of this drug as idarubicinol may have appreciable cytotoxic activity.

Plasma levels of daunorubicin metabolites and the outcome of ANLL therapy

Levels of plasma daunorubicin, daunorubicinol and aglycone metabolites were measured in 47 patients 3 h after daunorubicin was administered daily for three days as part of a cytosine arabinoside/daunorubicin remission induction regimen. High-pressure liquid chromatography with fluorescence detection was used for separation and quantitation of the drug and its metabolites. A wide range of plasma levels were observed regardless of the outcome of therapy. Patients who had high levels of the drug, or daunorubicinol on day 1 of therapy tended to have high levels on days 2 and 3 of the regimen. Three hours after the third daily dose of daunorubicin was administered, patients who would not enter remission had significantly higher levels of aglycone metabolites in plasma than did patients who entered remission. These data indicate that resistance to chemotherapeutic effects of daunorubicin may be connected with metabolism of the drug, especially with enhanced metabolism to aglycones.

Comparative uptake, retention and cytotoxicity of daunorubicin by human myeloid cells

We studied the cellular uptake and retention of daunorubicin (D1) in two human leukemic cell lines (ML1 and K562) and myecloblasts from an untreated patient with acute myelogenous leukemia (AML). The rate of uptake and the steady-state level of D1 were not temperature dependent but increased markedly with increases in the pH of the medium. Also, saturation kinetics were not demonstrable using concentrations of D1 up to 111 microM. Together, these observation suggest a transport mechanism for D1 compatible with passive diffusion. Accumulation of D1 was increased only in cells from the AML patient with addition of sodium azide, whereas drug efflux was not increased significantly in the presence of glucose in MLI or K562 cells. Although the rate of uptake and steady-state levels of D1 were the same in these cells, metabolism and cytotoxicity of D1 differed. Our results indicate that ML1 cells can be used as a pharmacologic model for studying the metabolism and resistance of D1 in vivo.

Daunorubicin reductase activity in human normal lymphocytes, myeloblasts and leukemic cell lines

To exploit the full potential of daunorubicin chemotherapy, it is necessary to understand its metabolism. We have shown previously that daunorubicin reduction in human liver is mediated by both aldehyde and ketone reductases. This study shows that this is also the case in normal blood cells. However, myeloblasts from AML patients show different pH profiles from those observed for normal lymphocytes. Human myeloid cell lines (KG1, ML1 and K562) accurately reflect the reductase heterogeneity seen in AML patients. This is in contrast to L1210 and P388 murine cell lines, which do not readily metabolize daunorubicin. When studying daunorubicin metabolism, it is important to use only cell lines that metabolize the drug because daunorubicin is extensively metabolized to daunorubicinol in AML patients. The use of human rather than rodent cell lines may provide useful information to increase our understanding of the in vivo situation.

The effect of surfactants on the high-performance liquid chromatography of anthracyclines

A rapid, reversed-phase high-performance liquid chromatographic method is described for the determination of the antineoplastic drug, doxorubicin (Adriamycin), and its major metabolites in plasma. The addition of anionic, cationic or non-ionic surfactants was found to reduce k'; the mechanisms of this finding are discussed and the performance of an optimized method using a non-ionic surfactant, Brij-35, is described for plasma samples.

Continuous extraction of urinary anthracycline antitumor antibiotics with the horizontal flow-through coil planet centrifuge

Extraction of doxorubicin (adriamycin) and daunorubicin and their metabolites from human urine was attempted utilizing the horizontal flow-through coil planet centrifuge. Partition coefficients of the drugs for various combinations of non-aqueous phases and aqueous salt solutions were determined. Optimal coefficients for adriamycin and daunorubicin were achieved with n-butanol-0.3 M disodium hydrogen phosphate. Extraction efficiencies of the drugs from human urine comparable to those obtained by standard resin column techniques could be realized by employing the n-butanol-urine (containing 0.3 M disodium hydrogen phosphate) system in the coil planet centrifuge, at flow-rates of 500-600 ml/h, and at 650 rpm revolutional speed. Small quantities of drugs and metabolites could be continuously concentrated into small volumes of the n-butanol phase from large volumes of salted urine. The versatility of the technique was demonstrated by its application to extraction of aclacinomycin A, a novel anthracycline antitumor agent, and its metabolites from human urine.

New anthracenedione derivatives: interaction with DNA and biological effects

Two anthracenedione derivatives [1 - (omega - diethylaminopropylamido) - 4 - hydroxy - 9,10 - anthracenedione hydrochloride (I) and 1 - (omega - diethylaminopropylamido) - 2 - methoxy - 4 - hydroxy - 9, 10 - anthracenedione hydrochloride (II)], having an electron-rich planar chromophore and an amino-substituted side chain, have been synthesized. Their binding ability to DNA was investigated by means of spectroscopic, equilibrium dialysis and fluorescence measurements. Their inhibition efficiency on nucleic acid synthesis was also evaluated both in mouse and human cells. Our results indicate that, in comparison with adriamycin, compound I shows a slightly weaker complexation ability to DNA, while compound II interacts with DNA at a substantially lower level. These data match quite well with the biological response on the inhibition of DNA and RNA synthesis exhibited by the above mentioned compounds; in fact compound I is slightly less efficient than adriamycin and about ten times more efficient than compound II. The close relationship between the results of physicochemical and biological studies is discussed.

An in vitro model for acute myelogenous leukemia chemotherapy

A human acute myelogenous leukemia cell line that forms colonies in soft-gel culture (KG-1) was used to test the effect of various schedules and combinations of chemotherapeutic agents. For comparison, the drug sensitivity of normal human marrow myeloid clonogenic cells was tested. Cytosine arabinoside inhibited both the KG-1 and normal human colony-forming cells (CFC) approximately 25% after a 2-hour exposure, 50% after a 5-hour exposure, and 90% after a 24-hour exposure. Daunorubicin had nearly an equal cytotoxic effect on KG-1 and normal marrow CFC after a 2- to 72-hour exposure to the drug. Daunorubicin at 0.15 micrograms/ml produced nearly complete inhibition of colony-forming cells. Amphotericin B also inhibited colony formation. Amphotericin B and daunorubicin, when combined in culture, produced a synergistic suppression of normal and leukemic CFC. The antileukemic agent 5-azacytidine at a concentration of 0.1 micrograms/ml produced approximately 60% inhibition of colony formation. Cytidine partially rescued CFC when the nucleoside was added in seven-fold excess to cultures containing 5-azacytidine. Leukemic and normal marrow clonogenic cells have nearly the same sensitivity to each chemotherapeutic agent and combination. Human acute myelogenous leukemia lines may provide useful models for the development of new chemotherapeutic schedules and combinations.

Pharmacokinetics of daunorubicin after administration as free drug or as DNA complex in leukemic patients

An earlier whole-body autoradiographic study in mice revealed large differences between the tissue distribution of daunorubicin (D) after administration as free drug as as DNA-linked D. Therefore, the pharmacokinetics of D administered as free drug or linked to DNA was studied in 15 adult patients with acute non-lymphoblastic leukemia. The data obtained following infusion of free drug over either 45 or 240 min could be fitted to a two-compartment open-body model. With the D-DNA infusion considerably higher plasma concentrations were achieved, with a slower distribution and elimination from plasma than seen after the administration of free drug. this confirmed earlier animal data indicating a different pharmacokinetic behavior of D when it was administered linked to DNA. Furthermore, different pharmacokinetic parameters were obtained for D during infusion and in the post-infusion phase after administration of DNA-linked D (P less than 0.005). This finding strongly indicates that the D-DNA acts as a slow-release preparation in humans, which might modify tissue distribution and toxic side-effects of the drug.

Analysis of carminomycin in human serum by fluorometric high-performance liquid chromatography

A method is given for the determination of carminomycin (CMM) and a major metabolite carminomycinol (CMMOH) in serum from cancer patients after intravenous administration of carminomycin as the free drug. CMM and CMMOH are extracted from serum with chloroform, the extract evaporated and the residue dissolved in methanol. High performance liquid chromatography analysis utilized a C18 microBondapak reversed-phase column eluted with 0.1 mol/l acetate buffer (pH 4)-acetonitrile (60:40, v/v) with fluorescence detection. The assay is linear, reproducible, and precise with a limit of detection of 2 ng/ml. Representative serum levels of CMM and CMMOH in a cancer patients are presented.

Will hemoperfusion be useful for cancer chemotherapeutic drug removal?

One of the major problems in clinical cancer chemotherapy is the inability to safely administer full therapeutic doses of specific drugs in the face of dysfunction of an organ system controlling that drug's metabolism and excretion. Should efficient drug removal from blood be possible following full therapeutic doses and after tumor exposure, then theoretically, even in the presence of organ dysfunction, anticancer drug toxicity may be reduced or avoided. Preliminary experiments in our laboratory have shown that adriamycin may be efficiently removed by activated charcoal from aqueous and protein solutions and blood in vivo, and that daunorubicin is removed in vitro to the same extent. However, although methotrexate is removed efficiently in vitro and extracted 50% in vivo by charcoal hemoperfusion, its overall pharmacokinetics do not appear to be altered in comparison with the alteration in pharmacokinetics of adriamycin achieved with charcoal hemoperfusion. Computer modeling has suggested that efficient adriamycin removal is achievable, and that clinical studies are warranted. For methotrexate removal, however, previous clinical studies and our own data suggest that charcoal hemoperfusion has little utility unless a highly specific sorbent for methotrexate removal can be developed.

Determination of daunorubicin and its main metabolites in plasma, urine and leukaemic cells in patients with acute myeloblastic leukaemia

The pharmacokinetics of daunorubicin were studied in 3 previously untreated patients with acute myeloblastic leukaemia by simultaneous monitoring of daunorubicin (DNR), daunorubicinol (DOL) and their aglycones in plasma, urine and leukaemic cells. The drug was given as an i.v. infusion in a dose of 1.5 mg/kg body wt. The plasma concentration of daunorubicin declined rapidly after the infusion. The concentration of daunorubicinol exceeded that of the parent compound only 5 min after the end of the infusion. Daunorubicin accumulated extensively in the leukaemic cells and reached concentrations there which exceeded the plasma concentration 400-4000 times. As compared to what was found in plasma, daunorubicinol appeared much slower in the leukaemic cells and the concentration ratio only reached 30-200. The concentration of aglycones was low in the leukaemic cells as well as in plasma. Only about 15% of the administered dose of daunorubicin could be recovered in the urine within 4 days, most of it as daunorubicinol. The results demonstrate that the plasma concentration of daunorubicin and its metabolites provides little information on the drug concentration in the leukaemic cells. Direct determinations of drug concentrations in the leukaemic cells might be of clinical value for optimization of the therapy in acute leukaemia.

Human pharmacokinetics of the daunorubicin-DNA complex. An alternative view of the lysosomotropic theory

Plasma kinetics and urinary execretion of daunorubicin (DNR) and its active metabolite, daunorubicinol (DNR-ol) were studied in 15 leukemic patients after a 4-h infusion of 75 mg DNR/m2 either as the free drug or as a complex with DNA. The data obtained after infusion of the DNR-DNA complex were compared with the data obtained after infusion of the free drug. The DNR plasma levels were found to be higher during the 2 h following the infusion of the complex; the levels of DNR-ol were only higher for a few minutes after infusion. Kinetic analysis showed that complexing with DNA does not fundamentally modify the three-compartment model described for DNR. Only quantitative modifications were observed: a marked lengthening of the alpha-phase and a shortening of the gamma-phase. Urinary excretion of DNR and DNR-ol was increased after infusion of the complexed drug, in relation to the persistence of higher plasma levels. The data recorded in this work do not confirm the lysosomotropic mechanism postulated for the DNR-DNA complex, but show a delayed distribution of DNR, which is progressively released by dissociation of the circulating DNR-DNA complex, as previously demonstrated in rabbits infused under same conditions.

Comparative metabolism and excretion of adriamycin in man, monkey, and rat

Adriamycin and its fluorescent metabolites in bile (man, monkey, and rat) and urine (man and monkey) were determined by means of a simple, rapid, and highly reproducible high-performance liquid chromatographic procedure. Species differences in metabolism and biliary excretion were observed with respect to aldoketo reductase and conjugase activities.

GLC--mass spectrometry of several important anticancer drugs II: doxorubicin and daunorubicin aglycone analogs

By using previously developed pertrimethylsilylation and methoxime formation procedures, the GLC--mass spectra of pertrimethylsilyl and pertrimethylsilyl methoxime derivatives of 12 doxorubicin and daunorubicin glycone analogs, mostly synthesized in this laboratory, were studied. The fragmentation pathways were readily interpretable, and the patterns were highly specific for corresponding structural changes, thus supporting the previous contention that this method has potential for the identification of doxorubicin and daunorubicin metabolites. Four aglycone metabolites were identified, on the basis of their GLC--mass spectra, in the hydrolysate of the 1-butanol extract of bile obtained from a doxorubicin-treated rabbit.

Extraction of daunorubicin and doxorubicin and their hydroxyl metabolites: self-association in aqueous solution

The extraction of daunorubicin and doxorubicin and their hydroxyl metabolites daunorubicinol and doxorubicinol was studied using chloroform-1-pentanol (9:1) as the organic phase. Because of differences in acid dissociation constants, the pH for optimum extraction varied from 8.0 to 8.6 for the different compounds. Self-association in the aqueous phase significantly influenced the distribution ratio. Constants for the formation of dimers and tetramers in aqueous solutions were about 10(4.5) and 10(12), respectively.

Liquid chromatographic determination of daunorubicin and daunorubicinol in plasma from leukemic patients

A method is given for the determination of daunorubicin and its main metabolite, daunorubicinol, in plasma from leukemic patients after administration of daunorubicin as the free drug or as a complex with DNA. Daunorubicin and daunorubicinol are extracted from 2 ml of plasma (pH 8.1) using a mixture of chloroform and 1-heptanol (9:1). After re-extraction into phosphoric acid (0.1 M), the separation is performed as reversed phase liquid chromatography on a LiChrosorb RP-2 (5 micrometer) column with a mobile phase of acetonitrile-water, acidified with phosphoric acid. The precision, by quantitation with a photometric detector, was better than 2% within the range 20 ng/ml to 200 ng/ml. Some determinations of plasma levels of daunorubicin and daunorubicinol are presented.

A pharmacokinetic evaluation of free and DNA-complexed adriamycin: a preliminary study in children with malignant disease

The pharmacokinetics of adriamycin given as free and in DNA-complexed form was compared in six children with malignant disease. The two types of adriamycin were given to the same child at 3--4-week intervals, thereby excluding genetic variations when comparing the results. Plasma and urine were collected during and after the drug infusion, and the drug concentrations were measured by means of a sensitive fluorimetric procedure. The study shows that one obtains: 1. a much higher plasma concentration of adriamycin when it is given in the complexed form. 2. a lower urine excretion of adriamycin and fluorescent metabolites when adriamycin is administered as the DNA-complex.

Reversed-phase liquid chromatography of adriamycin and daunorubicin and their hydroxyl metabolites adriamycinol and daunorubicinol

Adriamycin and daunorubicin and their metabolites adriamycinol and daunorubicinol were separated by reversed-phase liquid chromatography using LiChrosorb RP-2, RP-8 and RP-18 as supports and acetone, acetonitrile and alcohols as organic modifiers in the mobile phase. The highest separation selectivity was obtained using a mobile phase containing low concentrations (less than 20%) of acetonitrile. The length of the hydrocarbon chains of the surface-modified silica supports had no significant influence on the selectivity. The lowest capacity factor was obtained with 40-60% of organic solvent in the mobile phase. Increasing the length of the hydrocarbon chains of the supports increased the retention of the solutes.

Adriamycin and other anthracycline antibiotics under study in the United States

Adriamycin is now firmly established as a drug with a very broad spectrum of antitumor activity. It has had a major impact on the therapy of sarcomas. The dose response effect in this tumor is steep and combinations which compromise the dose of adriamycin too greatly are showing inferior results. In lung and breast cancer combinations with adriamycin have been extensively tried. The FAC Regimen in breast cancer has given excellent results at the M.D. Anderson Hospital. The inclusion of adriamycin in combinations has had an impact in the poor prognosis histologies of non-Hodgkin's lymphomas. The CHOP regimen is one of the best developed to date for diffuse histiocytic lymphomas. In the leukemias adriamycin is probably equivalent to daunorubicin which has been more extensively used in this country. A new analog called Rubidazone has shown good activity in AML with a smooth induction and its incorporation into combination with Ara-C, vincristine and prednisone in a regimen called ROAP is being investigated. Adriamycin in complex with DNA has been clinically evaluated, but at this time, no advantage for this approach can be demonstrated.

In vitro adsorption of doxorubicin hydrochloride on insoluble calcium phosphate

The adsorption of doxorubicin hydrochloride, a potent antitumor agent, on solid tribasic calcium phosphate was studied in vitro. A Langmuir adsorption isotherm at pH 7.4 and the maximum adsorption capacity of tribasic calcium phosphate were established. Tribasic calcium phosphate was chosen as a model for solid bone samples, which are stained with doxorubicin in patients who have received long-term doxorubicin therapy.

Electronic absorption spectra and protolytic equilibria of doxorubicin: direct spectrophotometric determination of microconstants

The ground- and excited-state dissociation constants and the electronic absorption and fluorescence spectra of doxorubicin were investigated by spectrophotometry. A general method for the direct calculation of individual microscopic dissociation constants was derived using the spectrophotometric data obtained. It was concluded that the protonated amino sugar group is slightly more acidic than the phenolic group. The spectrophotometric data were analyzed, and the macro- and microconstants for the various equilibria was reported.