Pharmacokinetics Of Doxorubicin Research Articles

Clinical and Pharmacokinetic Characteristics of Intracavitary Administration of Pegylated Liposomal Encapsulated Doxorubicin in Dogs with Splenic Hemangiosarcoma

Canine splenic hemangiosarcoma (HSA) is a fatal malignancy, and most affected dogs die within a few months of diagnosis. Most dogs present with signs from tumor rupture, resulting in hemoabdomen and intra-abdominal dissemination. The abdomen is also the main site of disease recurrence. Intraperitoneal (IP) administration of doxorubicin will delay or prevent intra-abdominal tumor recurrence and prolong survival in dogs with HSA. Fourteen dogs with splenic HSA. A prospective, unmasked, uncontrolled clinical trial. After staging of disease status and splenectomy, pegylated liposomal encapsulated doxorubicin was administered intraperitoneally (1 mg/kg body weight) every 3 weeks for 4 cycles. All dogs were monitored for recurrence of HSA. Samples of plasma and abdominal fluid were collected for measurement of doxorubicin concentration and pharmacokinetic analysis. Nonlinear mixed-effect modeling was used to describe the pharmacokinetics of liposomal doxorubicin administered IP. All 14 dogs died, 12 because of HSA and 2 from other causes. Postmortem examination was performed on 12 dogs. All 12 dogs died because of HSA-related causes and had hepatic metastases and hemoabdomen. The IP-treated dogs had fewer serosal, mesenteric, and omental metastases than historical controls treated with systemic doxorubicin. Results of the postmortem examination and pharmacokinetic analysis confirmed that IP delivery of doxorubicin resulted in an effective drug concentration with a clearance comparable with that after i.v. delivery. IP pegylated liposomal encapsulated doxorubicin administration did not prevent intraabdominal recurrence of HSA in dogs.

Phase I/II trial of a P-glycoprotein inhibitor, Zosuquidar.3HCl trihydrochloride (LY335979), given orally in combination with the CHOP regimen in patients with non-Hodgkin's lymphoma

A phase I/II trial was performed to investigate the safety and tolerance of zosuquidar.3HCL, a potent inhibitor of P-glycoprotein (P-gp), when administered orally alone and in combination with the CHOP regimen in patients with untreated non-Hodgkin's lymphoma and to determine whether zosuquidar.3HCL affects pharmacokinetics of doxorubicin and vincristine. Doses of CHOP remained constant and the doses of zosuquidar.3HCL were increased from 200 to 500 mg per dose. A total of 15 patients were treated at three dose levels. A target dose providing peak and trough levels compatible with prolonged modulation of P-gp function was obtained in patients receiving three doses of 500 mg of zosuquidar.3HCL p.o. At this dose level, toxicity was minimal and no enhancement of CHOP-related toxicity was observed. Zosuquidar.3HCL did not significantly affect the pharmacokinetics of doxorubicin and had moderate effects on the pharmacokinetics of vincristine. Zosuquidar.3HCL can be safely administered with CHOP therapy using a 24-h schedule.

Vitamin E but not St. John’s wort mitigates leukopenia caused by cancer chemotherapy in rats

Dietary supplements are used by most patients with cancer. As nutraceuticals can interact with many drugs, this study investigated the effect of herbal remedies and vitamins on the toxicity of representative cancer chemotherapeutic agents. Fisher 344 rats were fed a standard cereal-based diet or the same diet with additional vitamin E in low (50 mg/kg) or high (750 mg/kg) concentrations, or with added St. John's wort (400 mg/kg). The LD50 was determined after the administration of chemotherapy drugs. Neither low or high vitamin E supplements nor St. John's wort significantly changed the LD50 for doxorubicin, docetaxel, or cyclophosphamide. The nadir white blood cell (WBC) count was significantly higher (P = 0.004) after docetaxel in rats supplemented with low-dose vitamin E, but the drop in WBC count from initial to nadir levels (Nfall) was greater in rats fed a diet containing high vitamin E supplementation (P = 0.04). Similarly, the Nfall was greater in the standard and high vitamin E dietary groups than in the low vitamin E group after cyclophosphamide (P = 0.03). No effect of vitamin E or St. John's wort supplementation occurred on doxorubicin pharmacokinetics. Neither vitamin E nor St. John's wort had an important effect on the mitochondrial deoxyribonucleic acid (DNA) damage caused by either doxorubicin or docetaxel. These data suggest that the leucopenia caused by some chemotherapeutic agents can be modified by dietary supplementation with vitamin E, but the effect seems to be dose-dependent. St. John's wort had neither a beneficial nor a detrimental effect on chemotherapy-induced toxicity.

Chemoembolization of hepatocellular carcinoma with drug eluting beads: Efficacy and doxorubicin pharmacokinetics

This study assesses the safety, pharmacokinetics and efficacy of transarterial chemoembolization using drug eluting beads (DEB), an embolizing device that slowly releases chemotherapy to decrease systemic toxicity. Twenty-seven Child-Pugh A cirrhotics (76% male, 59% HCV) with untreated large/multifocal HCC received chemoembolization with doxorubicin loaded DEBs at doses adjusted for bilirubin and body surface (range: 47-150 mg). Clinical and analytical data were recorded at 24 and 48 h, 7, 14 and 30 days after first and second TACE. Response rate was assessed by CT at 6 months. Blood samples were obtained in 13 patients at 5, 20, 40, 60, 120 min, 6, 24, 48 and 168 h to determine doxorubicin Cmax and AUC. DEB-TACE was well tolerated with an acceptable safety profile. Two cases developed liver abscess, one leading to death. Response rate was 75% (66.6% on intention-to-treat). Doxorubicin Cmax and AUC were significantly lower in DEB-TACE patients (78.97+/-38.3 ng/mL and 662.6+/-417.6 ng/mLmin) than in conventional TACE (2341.5+/-3951.9 ng/mL and 1812.2+/-1093.7 ng/mLmin, p=0.00002 and p=0.001, respectively). After a median follow-up of 27.6 months, 1- and 2-year survival is 92.5% and 88.9%, respectively. Chemoembolization using DEBs is an effective procedure with a favorable pharmacokinetic profile.

Phase 1 Clinical Study of Pegylated Liposomal Doxorubicin (JNS002) in Japanese Patients with Solid Tumors

Pegylated liposomal doxorubicin (PLD, JNS002) is a formulation of doxorubicin encapsulated polyethylene-glycol coated liposomes with prolonged circulation time and unique toxicity profile. This phase 1 study was aimed at investigating the maximum tolerated dose (MTD), recommended dose, toxicity, pharmacokinetics, and antitumor activity in Japanese patients with solid tumors. Patients with solid tumors not amenable to standard forms of treatment were eligible. PLD was administered as an intravenous infusion every 4 weeks. Dose escalation of PLD was planned from 30 to 60 mg/m(2) in 10 mg/m(2) increments. The pharmacokinetics of total doxorubicin (encapsulated plus non-encapsulated) in plasma were examined for the first cycle of treatment. Fifteen patients, aged 49-69 (median; 56) years with advanced solid tumors were enrolled. The major non-hematological toxicities were hand-foot syndrome (HFS), rash and stomatitis. Myelosuppression, especially leukopenia and neutropenia were major hematological toxicities. Although HFS was not severe, a delay of doses for subsequent cycles was required with multiple dosing. The peak plasma concentration and the area under the concentration time curve of PLD increased proportionally to the dose. Objective response was observed in one patient and the normalization of tumor marker values in another. These two patients had been diagnosed with ovarian cancer. The recommended dose for phase 2 clinical studies of PLD in Japanese patients was 50 mg/m(2) every 4 weeks. The encouraging results prompted us to plan a subsequent clinical study of PLD against ovarian cancer.

Results of a Phase I trial of sorafenib (BAY 43-9006) in combination with doxorubicin in patients with refractory solid tumors

Sorafenib (BAY 43-9006), a novel, oral multi-kinase inhibitor, blocks serine/threonine and receptor tyrosine kinases in the tumor and vasculature. Sorafenib demonstrated single-agent activity in Phase I studies, and was tolerated and inhibited tumor growth in combination with doxorubicin in preclinical studies. This Phase I dose-escalation study determined the safety, pharmacokinetics and efficacy of sorafenib plus doxorubicin. Thirty-four patients with refractory, solid tumors received doxorubicin 60 mg/m(2) on Day 1 of 3-week cycles, and oral sorafenib from Day 4 of Cycle 1 at 100, 200 or 400 mg bid. Common drug-related adverse events were neutropenia (56%), hand-foot skin reaction (44%), stomatitis (32%), and diarrhea (32%). The maximum tolerated dose was not reached. One patient with pleural mesothelioma achieved a partial response (modified WHO criteria) and remained on therapy for 39.7 weeks. Fifteen patients (48%) achieved stable disease for >/=12 weeks. Doxorubicin exposure increased moderately with sorafenib 400 mg bid. The pharmacokinetics of sorafenib and doxorubicinol were not affected. Sorafenib 400 mg bid plus doxorubicin 60 mg/m(2) was well tolerated. The increased doxorubicin exposure with sorafenib 400 mg bid did not result in significantly increased toxicity; low patient numbers make the clinical significance of this unclear. These promising efficacy results justify further clinical investigation.

Doxorubicin pharmacokinetics is correlated to the effect of induction therapy in children with acute myeloid leukemia

We studied the pharmacokinetics of doxorubicin in 41 children treated for newly diagnosed acute myeloid leukemia. Doxorubicin, 75 mg/m2 body surface area, was administered by constant i.v. infusion over 8 h. Four children with Down's syndrome (DS), 1.2-2.3 years old, had a median total body clearance of 523 ml/min/m2. The median clearance in non-DS children, 0.6-1.8 years old (n = 4) and 2.5-17.7 years old (n = 33), was 446 and 538 ml/min/m2, respectively. Patients who went into complete remission (CR) after induction therapy had a significantly higher median plasma concentration of doxorubicin than those who did not, 249 compared with 180 ng/ml, respectively (P = 0.036; analysis restricted to non-DS patients). Doxorubicin plasma concentration was an independent factor for CR, both in univariate (P = 0.031) and multivariate analysis including sex, age and white blood cell count at diagnosis (P = 0.021). Patients who reached CR had a significantly lower doxorubicin clearance than those who did not, 513 and 657 ml/min/m2, respectively (P = 0.017). In conclusion, doxorubicin plasma concentration and total body clearance during up-front treatment were correlated to the effect of induction therapy. Prospective studies should be performed to confirm the concentration-effect relationship and explore the possibility of therapeutic monitoring.

Evaluation of the effects of dietary n-3 fatty acid supplementation on the pharmacokinetics of doxorubicin in dogs with lymphoma

To determine the effect of dietary n-3 fatty acids on the pharmacokinetics of doxorubicin in dogs with lymphoma. 23 dogs with lymphoma in stages IIIa, IVa, and Va. Dogs receiving doxorubicin chemotherapy were randomly allocated to receive food with a high (test group) or low (control group) content of n-3 fatty acids. Serum doxorubicin and doxorubicinol concentrations were measured via high-performance liquid chromatography before and 6 to 9 weeks after initiation of the diets. Lymph node concentrations of doxorubicin were assessed 6 hours after the initial treatment. Dogs' body composition was assessed by means of dual-energy x-ray absorptiometry scans. No significant differences in doxorubicin pharmacokinetics were detected between treatment groups. Significant differences existed between the first and second sampling times among all dogs for area under the curve, maximum serum concentration, and clearance. Differences in body composition did not affect measured pharmacokinetic variables. The terminal elimination half-life was longer in dogs in which a long-term remission was achieved than in dogs that did not have remission. Dietary supplementation of n-3 fatty acids is common in veterinary patients with neoplasia, but supplementation did not affect doxorubicin pharmacokinetics in this population of dogs. Explanations for the beneficial effects of n-3 fatty acids other than alterations in the pharmacokinetics of chemotherapy drugs should be investigated. Dogs may metabolize drugs differently prior to remission of lymphoma than when in remission. The pharmacokinetics of doxorubicin at the time of the first administration may predict response to treatment.

Effect of Repetitive Administration of Doxorubicin-Containing Liposomes on Plasma Pharmacokinetics and Drug Biodistribution in a Rat Brain Tumor Model

The incorporation of doxorubicin in long-circulating sterically stabilized liposomes (SSL-DXR) alters the pharmacokinetics and biodistribution of doxorubicin and therefore has the potential to alter the pharmacologic properties of doxorubicin. Previously, we showed that repetitive administration of SSL-DXR alters tumor vascular permeability. Here, we investigated the effect of weekly i.v. injections of SSL-DXR on plasma pharmacokinetics and drug biodistribution in the orthotopic 9L rat brain tumor model. The pharmacokinetics of free doxorubicin (5.67 mg/kg) did not change with repeat dosing. In contrast, drug concentrations in plasma and brain tumor increased and deposition in liver and spleen decreased after administration of the second of two weekly doses of SSL-DXR. Noncompartmental analysis and descriptive pharmacokinetic models were created to test hypotheses relating to the mechanisms responsible for alterations in SSL-DXR deposition. The analysis suggested that weekly administration of SSL-DXR significantly (P < 0.05) decreased the plasma elimination rate of SSL-DXR (34%) and decreased drug deposition in liver (2-fold) and spleen (3.5-fold). The pharmacokinetic model that best captured the observed 2.5-fold increase in tumor uptake of SSL-DXR mediated by repeat dosing was one that hypothesized that the rates of drug influx/efflux into tumor were increased by the first dose of SSL-DXR. Models that accounted only for residual drug deposited in the tissue or blood by the first weekly injection provided inferior fits to the data. Thus, the effects of repetitive dosing on SSL-DXR deposition in tumor are consistent with a treatment-mediated alteration of tumor vascular permeability.

Pharmacokinetics of intravenously administered stealth liposomal doxorubicin modulated with verapamil in rats

Treatment of cancer through co-administration of anticancer drugs and multidrug resistance (MDR) modulators as a strategy to overcome drug resistance has been extensively explored. However, success has been limited by pharmacokinetic interactions because of non-specific blockade of P-glycoprotein (P-gp) in normal tissues or inability to reach relevant concentrations clinically. We hypothesized that stealth liposomal co-encapsulation of doxorubicin (DOX) with a P-glycoprotein inhibitor, verapamil (DARSLs), may overcome these limitations. Using intravenous (i.v.) administrations, the effects of verapamil (VER) either free (FV) or liposome co-encapsulated with DOX (DARSLs) on the pharmacokinetics and tissue distribution characteristics of DOX either as free (FD) or liposome-encapsulated (LD) were evaluated in normal rats. FV increased ( P<0.05) the plasma AUC of free DOX (FD). Preparations containing LD had significant prolonged systemic exposure and slow tissue distribution of DOX. LDFV (liposomal DOX with free verapamil) and DARSLs shared similar DOX pharmacokinetics but the latter showed slower DOX distribution in most tissues studied and slower ( P<0.05) DOX biliary transport. The addition of VER into LD in these two preparations significantly increased the AUC ( P<0.01) and reduced the clearance ( P<0.01) of DOX when compared to LD. Specifically, DARSLs reduced initial DOX distribution to the heart ( P<0.05) corresponding to initial alleviation ( P<0.05) of bradycardia when compared to other DOX with VER preparations. In conclusion, liposomal co-encapsulation of DOX with VER has promise of significant therapeutic advantages, and should be explored further in therapeutic studies with animal tumor xenograft models.

Alteration of the Pharmacokinetics of COL-3, a Matrix Metalloproteinase Inhibitor, Due to Acute Gastrointestinal Toxicity of Doxorubicin

Combination of COL-3, a matrix metalloproteinase inhibitor, and doxorubicin (DOX) might be a promising anticancer regimen. The present study was to examine the potential pharmacokinetic interactions and toxicity profile following their coadministration in rats. Normal rats were treated with single agent or different combinations with oral or intravenous COL-3 and DOX, and the bile-duct cannulated (BDC) rats received oral COL-3 plus DOX. In a separate disposition study, the effects of DOX on the biliary, urinary, and fecal excretion of COL-3 were examined. In addition, the effects of DOX on in vitro protein binding, metabolism, and transport of COL-3 across Caco-2 monolayers were investigated. COL-3 did not affect the pharmacokinetics of DOX in rats. However, treatment with DOX significantly decreased the oral absorption, and prolonged the elimination, of COL-3 in the normal rats, but not in the BDC rats. DOX did not alter the biliary and urinary excretion of COL-3, but significantly decreased the fecal excretion of COL-3. DOX significantly enhanced the basolateral to apical flux of COL-3 across Caco-2 monolayers, but had no apparent effects on the protein binding and metabolism of COL-3. The combination of DOX with oral COL-3 did not significantly (p > 0.05) increase the acute diarrhea score and intestinal damage compared to rats receiving DOX alone. These results indicated that DOX altered the oral absorption and elimination of COL-3, largely resulting from gastrointestinal toxicity caused by biliary excretion of DOX. Further studies are required to explore the efficacy and optimized dosage regimen of this promising combination.

Phase I study of pegylated liposomal doxorubicin and the multidrug-resistance modulator, valspodar

Valspodar, a P-glycoprotein modulator, affects pharmacokinetics of doxorubicin when administered in combination, resulting in doxorubicin dose reduction. In animal models, valspodar has minimal interaction with pegylated liposomal doxorubicin (PEG-LD). To determine any pharmacokinetic interaction in humans, we designed a study to determine maximum tolerated dose, dose-limiting toxicity (DLT), and pharmacokinetics of total doxorubicin, in PEG-LD and valspodar combination therapy in patients with advanced malignancies. Patients received PEG-LD 20–25 mg m−2 intravenously over 1 h for cycle one. In subsequent 2-week cycles, valspodar was administered as 72 h continuous intravenous infusion with PEG-LD beginning at 8 mg m−2 and escalated in an accelerated titration design to 25 mg m−2. Pharmacokinetic data were collected with and without valspodar. A total of 14 patients completed at least two cycles of therapy. No DLTs were observed in six patients treated at the highest level of PEG-LD 25 mg m−2. The most common toxicities were fatigue, nausea, vomiting, mucositis, palmar plantar erythrodysesthesia, diarrhoea, and ataxia. Partial responses were observed in patients with breast and ovarian carcinoma. The mean (range) total doxorubicin clearance decreased from 27 (10–73) ml h−1 m−2 in cycle 1 to 18 (3–37) ml h−1 m−2 with the addition of valspodar in cycle 2 (P=0.009). Treatment with PEG-LD 25 mg m−2 in combination with valspodar results in a moderate prolongation of total doxorubicin clearance and half-life but did not increase the toxicity of this agent.

Impact of body composition on pharmacokinetics of doxorubicin in pediatric patients: A Glaser Pediatric Research Network study

8519 Background Body composition affects various physiologic processes involved in the distribution, metabolism, and elimination of drugs. Therefore body composition might be related to important pharmacokinetic (PK) parameters like clearance or half-life. These relationships have never been systematically studied for doxorubicin (dox) and its metabolite doxorubicinol (doxol). In addition, the PK behavior of dox and doxol have not been thoroughly described in children. In this study we evaluated the relationship between body composition and doxorubicin PK in children. Methods Eligible subjects were ≥ 1 and ≤ 21 years old; weighed ≥ 12 kg; received dox administered as an infusion of any duration < 24 hours, on either a 1-day or 2-day schedule; had ALT/AST ≤ 3 times the upper limit of normal and bilirubin ≤ upper limit of normal tested within 14 days prior to dox; and provided informed consent/assent. Blood samples were drawn prior to dox administration, at the midpoint of the infusion and at 0, 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, 24, and 48 hours after the infusion for 1-day schedules, or at 0, 0.5, 1, 2, 4, and 6, hours after the day 1 infusion and immediately prior to the day 2 infusion, then at 0, 0.5, 1, 1.5, 2, 4, 6, 8, 12, 24, and 48 hours after the day 2 infusion for 2-day schedules. Body composition was determined using dual-energy x-ray absorptiometry (DXA). Body mass index (BMI) was calculated from height and weight. Dox and doxol concentrations were analyzed by reverse-phase high-pressure liquid chromatography with fluorescence detection. Dox plasma PK were analyzed with maximum likelihood estimation as implemented in ADAPT II. Results Data are available for 16 subjects (12 male; 8 Hispanic, 6 Caucasian, 2 Asian). The median age is 15 years (range 3–21). The median % body fat by DXA is 22 % (range 16–36). The median BMI is 20 (range 14–30). The median dox clearance is 382 ml/m2/min (range 141–768). The median terminal half-life is 30.6 hr (range 18.1–146.6). Dox clearance decreases with increasing BMI (r=-0.56, P=0.02) and tends to decrease with increasing % body fat (r=-0.43, P=0.10). Conclusions Potential relationships between increasing BMI, decreasing dox clearance, and dox toxicity should be explored. No significant financial relationships to disclose.

Pharmacokinetics of low-dose doxorubicin and metabolites in patients with AIDS-related Kaposi sarcoma

Systemic chemotherapy is the treatment of choice for AIDS-related advanced Kaposi sarcoma. One principal schedule combines adriamycin (doxorubicin), bleomycin, and vincristine (ABV). We analysed the plasma concentrations of low-dose doxorubicin (Dx) and its metabolites doxorubicinol, 7-deoxydoxorubicinone, doxorubicinone, doxorubicinolone, and 7-deoxydoxorubicinolone in AIDS-patients to define patient-group and dose-specific pharmacokinetic parameters. A previously described high-performance liquid chromatographic (HPLC) method and a population approach with non-linear mixed effects modelling (NONMEM) were used for analysis and subsequent modelling of the time-concentration data of low-dose Dx and metabolites in seven patients with AIDS-related advanced Kaposi sarcoma. Patients received Dx 20 mg m(-2), bleomycin 15 U m(-2) and vincristine 2 mg as a 30-min intravenous infusion each. Blood samples were collected up to 72 h after the start of Dx treatment. WinNonlin software version 4.1 was used for non-compartmental analysis and NONMEM software version V for compartmental analysis. Covariate analysis was performed for various clinical and laboratory parameters. Non-compartmental analysis yielded an area under the plasma concentration-time curve (AUC) for Dx of 566 mug h L(-1), a maximum plasma concentration (c(max)) of 599 mug L(-1) and an elimination half-life (t(1/2)) of 30.8 h. Compartmental analysis resulted in a two-compartment model with first-order elimination, which best fitted the concentration-time data. Model estimate for Dx clearance was 61.8 L h(-1), for intercompartmental clearance (Q) 112 L h(-1), for the volume of the central compartment (V(1)) 23.3 L, and for the volume of the peripheral compartment (V(2)) 1,130 L. Metabolite data could adequately be estimated by NONMEM using single-compartment models. Graphical plots of residuals versus time for all metabolites yielded no evidence of non-linear pharmacokinetic behaviour. Laboratory parameters of liver and renal function were all in the normal range and their inclusion in the pharmacokinetic model did not improve data fit. A final jack-knife analysis was performed. Concentration-time data for low-dose Dx and metabolites in the ABV-regimen are best described by a two-compartment model with first-order elimination. The results confirm that the aglycones doxorubicinone, 7-deoxydoxorubicinone, and doxorubicinolone can be reliably detected in the studied patient group and implemented into a common metabolic model. Model estimates suggest that pharmacokinetic parameters are similar for low-dose Dx and higher-dosed Dx. As the role of the aglycones is still poorly understood, despite their potential clinical relevance, their analysis should be implemented in future pharmacokinetic and pharmacodynamic studies of Dx.

Effect of highly active antiretroviral therapy (HAART) on pharmacokinetics and pharmacodynamics of doxorubicin in patients with HIV-associated non-Hodgkin's lymphoma

We demonstrated that highly active antiretroviral therapy (HAART) increases the toxic effect of cyclophosphamide, vincristine, doxorubicin (DOX) and prednisone (CHOP) in HIV-patients with non-Hodgkin's lymphoma (NHL). To ascertain the cause of increased toxicity, we investigated the pharmacokinetics of DOX in HIV-patients with NHL treated with CHOP with and without HAART. Complete pharmacokinetics and pharmacodynamic analysis was determined in 19 patients during 38 cycles of chemotherapy: 19 cycles with CHOP and 19 CHOP + HAART in a crossover-designed study. HAART included protease inhibitors indinavir (IDV) in nine patients, saquinavir (SQV) hard gel in six patients and nelfinavir (NFV) in four patients. No significant effects of HAART on pharmacokinetics parameters of DOX were observed. Similarly, no differential effect on DOX pharmacokinetics among IDV, SQV, and NFV was evidenced. Significant associations (P=0.012) were observed between DOX AUC0-infinity (area under the concentration curve) and G3-G4 WHO haematologic toxicity, in patients treated with CHOP alone, but not in those treated with CHOP + HAART (P = not significant). We demonstrated that HAART therapy has no significant effect on DOX pharmacokinetics. DOX AUC appears to be a predictor of toxicity only in patients treated with CHOP alone. Other factors beside DOX plasma levels are detrimental for toxicity after CHOP + HAART. Therefore, pharmacodynamic interactions between HAART and DOX should be considered.

Doxorubicin pharmacokinetics following a single‐dose infusion to sulphur‐crested cockatoos (Cacatua galerita)

To determine the pharmacokinetics of doxorubicin in sulphur-crested cockatoos, so that its use in clinical studies in birds can be considered. A pharmacokinetic study of doxorubicin, following a single intravenous (i.v.) infusion over 20 min, was performed in four healthy sulphur-crested cockatoos (Cacatua galerita). Birds were anaesthetised and both jugular veins were cannulated, one for doxorubicin infusion and the other for blood collection. Doxorubicin hydrochloride (2 mg/kg) in normal saline was infused i.v. over 20 min at a constant rate. Serial blood samples were collected for 96 h after initiation of the infusion. Plasma doxorubicin concentrations were assayed using an HPLC method involving ethyl acetate extraction, reverse-phase chromatography and fluorescence detection. The limit of quantification was 20 ng/mL. Established non-parametric methods were used for the analysis of plasma doxorubicin data. During the infusion the mean +/- SD for the Cmax of doxorubicin was 4037 +/- 2577 ng/mL. Plasma concentrations declined biexponentially immediately after the infusion was ceased. There was considerable intersubject variability in all pharmacokinetic variables. The terminal (beta-phase) half-life was 41.4 +/- 18.5 min, the systemic clearance (CI) was 45.7 +/- 18.0 mL/min/kg, the mean residence time (MRT) was 4.8 +/- 1.4 min, and the volume of distribution at steady state (V(SS)) was 238 +/- 131 mL/kg. The extrapolated area under the curve (AUC(0-infinity)) was 950 +/- 677 ng/mL x h. The reduced metabolite, doxorubicinol, was detected in the plasma of all four parrots but could be quantified in only one bird with the profile suggesting formation rate-limited pharmacokinetics of doxorubicinol. Doxorubicin infusion in sulphur-crested cockatoos produced mild, transient inappetence. The volume of distribution per kilogram and terminal half-life were considerably smaller, but the clearance per kilogram was similar to or larger than reported in the dog, rat and humans. Traces of doxorubicinol, a metabolite of doxorubicin, were detected in the plasma.

A mathematical model of Doxorubicin treatment efficacy for non-Hodgkin’s lymphoma: investigation of the current protocol through theoretical modelling results

Doxorubicin treatment outcomes for non-Hodgkin’s lymphomas (NHL) are mathematically modelled and computationally analyzed. The NHL model includes a tumor structure incorporating mature and immature vessels, vascular structural adaptation and NHL cell-cycle kinetics in addition to Doxorubicin pharmacokinetics (PK) and pharmacodynamics (PD). Simulations provide qualitative estimations of the effect of Doxorubicin on high-grade (HG), intermediate-grade (IG) and low-grade (LG) NHL. Simulation results imply that if the interval between successive drug applications is prolonged beyond a certain point, treatment will be inefficient due to effects caused by heterogeneous blood flow in the system.

A phase I and pharmacologic study of the MDR converter GF120918 in combination with doxorubicin in patients with advanced solid tumors

Resistance to chemotherapy can partly be explained by the activity of membrane bound P-glycoprotein. Competitive inhibition of P-glycoprotein, by multidrug resistance (MDR) converters, may overcome this MDR. Previously studied MDR converters either have serious intrinsic side effects or considerably influence the pharmacokinetics of cytotoxic agents at concentrations theoretically required to convert MDR. GF120918 is a third-generation MDR converter with high affinity for P-glycoprotein and can be given orally. We performed a phase 1 study with escalating doses of GF120918 in combination with doxorubicin. The study group comprised 46 patients with advanced solid tumors. Doxorubicin was administered on day 1 (cycle 1), GF120918 on days 22-24 (cycle 2), and on days 29-33 with doxorubicin administered on day 31 (cycle 3). Pharmacokinetics of both GF120918 and doxorubicin were studied. The starting daily dose of GF120918 was 50 mg and was to be increased in subsequent cohorts until a steady state plasma level of 100 ng/ml was reached. The starting dose of doxorubicin was 50 mg/m2 and was to be increased after reaching the target dose level of GF120918. In 37 of the 46 patients, full pharmacokinetic data from the three scheduled cycles were obtained. Pharmacokinetics of GF120918 showed a less than linear increase in Cmax with increasing doses, with considerable interpatient variation. The target steady-state plasma level for GF120918 was exceeded in 12 out of 19 patients who received 400 mg GF120918 alone twice daily and in 12 of 17 patients who received 400 mg GF120918 twice daily in combination with doxorubicin. GF120918 pharmacokinetics were not influenced by coadministration of doxorubicin. The doxorubicin AUC was only marginally influenced by GF120918 and only at the highest dose levels. In these patients there was a significant increase in the AUC of doxorubicinol in cycle 3 as compared to cycle 1. Hematologic toxicity mainly consisted of neutropenia and was more severe in cycle 3 than in cycle 1 (13 vs 5 patients with grade 4 neutropenia, P=0.003). Neutropenic fever was the dose-limiting toxicity at a doxorubicin dose of 75 mg/m2 with 400 mg GF120918 twice daily. The toxicity of GF120918 was limited to somnolence in eight patients and occasional gastrointestinal complaints. GF120918 is an MDR converter with only minimal side effects at a dose level yielding concentrations able to convert the action of P-glycoprotein in vitro. A doxorubicin dose of 60 mg/m2 on day 3 in combination with 400 mg GF120918 twice daily on days 1-5 is an acceptable regimen for further clinical trials.

Results of a phase I trial of BAY 43–9006 in combination with doxorubicin in patients with refractory solid tumors

3049 Background:BAY 43–9006 (BAY) is a novel signal transduction inhibitor that prevents tumor cell proliferation and angiogenesis through blockade of the Raf/MEK/ERK pathway at the level of Raf kinase and the receptor tyrosine kinases VEGFR-2 and PDGFR-β. Previous single-agent phase I studies show BAY is well tolerated, with manageable and reversible side effects, most commonly hand-foot skin (HFS) reaction, rash, fatigue, and diarrhea. This phase I study was initiated to determine the safety and pharmacokinetics (PK) of BAY in combination with doxorubicin. Methods:Patients (pts) received a fixed dose of doxorubicin (60 mg/m2 q x 3weeks) starting on day 1 of cycle 1 (C1). BAY was given on days 4–21 in C1 and continuously thereafter. BAY doses were 100 mg bid (cohort 1) escalating to 200 mg bid (cohort 2) and 400 mg bid (cohorts 3 and 4). Results:34 pts (M:F, 21:13; median age 60 yrs range 33–73) were treated. Common tumor types were CRC (15%), pancreatic cancer (15%) and HCC (12%). Dose-limiting leuko/neutropenia was seen in cohort 1 (1/6 pts) and cohort 3 (6/22 pts); all were related to doxorubicin therapy. Dose-limiting grade 3 skin toxicity (HFS reaction) occurred in 4/22 pts in cohort 3, which was related to BAY therapy. Non-DLTs were doxorubicin-related leuko/neutropenia, occurring 3 times in cohort 1, 4 times in cohort 3, and 2 times in cohort 4, and BAY-related HFS reactions in 5 pts from cohort 3. Steady-state BAY PK was not significantly influenced by concomitant doxorubicin medication when C1 and C2 were compared. Multiple BAY dosing had no consistent effect on the PK of doxorubicin or its metabolite doxorubicinol. Seventeen (53%) pts had a best response according to RECIST of PR (1 pt with mesothelioma) or SD (16 pts); 11 of these pts were from the 400 mg bid cohort. Conclusions:The combination of BAY and doxorubicin appears to be well tolerated and an extension in pts with HCC is ongoing. Most frequent AEs were related to doxorubicin. Most BAY-related AEs were mild (grade 1/2). No clinically relevant PK interaction between BAY and doxorubicin was observed. The recommended dose of BAY for phase II studies in combination with doxorubicin is 400 mg bid BAY. Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Bayer AG, Wuppertal, Germany, Bayer Corp. Bayer AG, Wuppertal, Germany

Comparison of doxorubicin concentration profiles in radiofrequency-ablated rat livers from sustained- and dual-release PLGA millirods.

To evaluate and compare the local pharmacokinetics of doxorubicin in radiofrequency (rf)-ablated rat livers after interstitial delivery from sustained- and dual-release poly(D,L-lactide-co-glycolide) (PLGA) millirods. PLGA millirods with sustained- and dual-release kinetics (burst followed by sustained release) of doxorubicin were implanted in rf-ablated rat livers. Doxorubicin release kinetics in vivo were measured from explanted millirods by UV-Vis spectrophotometer over 8 days. Spatial distribution of doxorubicin in liver tissues was measured by fluorescence imaging. In the initial 24 h after millirod implantation, dual-release millirods released significantly more doxorubicin into liver tissues than the sustained millirods. Subsequently, both types of millirods provided comparable sustained-release kinetics over 8 days. With dual-release millirods, doxorubicin concentration and penetration distance in liver tissue increased more rapidly. To reach 30 microg/g doxorubicin concentration at the ablation boundary (targeted site of action), the time required was 6 days and 1.5 days for sustained- and dual-release millirods, respectively. Compared with sustained-release millirods, dual-release millirods provide a quick concentration elevation and sustaining of the drug concentration at the ablation boundary. Additionally, the steady-state drug concentration agrees well with model predictions based on previously determined transport parameters, which demonstrates the feasibility of rational design of drug formulations in polymer millirods.