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Biomedical subjects

L B Grochow

Publications and source records attributed to L B Grochow.

At least 73 records · Page 4Linked to original sources
PubMed1992

Intrathecal 4-hydroperoxycyclophosphamide: neurotoxicity, cerebrospinal fluid pharmacokinetics, and antitumor activity in a rabbit model of VX2 leptomeningeal carcinomatosis.

Dissemination of tumor to the leptomeninges and cerebrospinal fluid represents a common pattern of metastasis for many cancers; however, few chemotherapeutic agents are available for intrathecal (i.t.) use and treatment results are often poor. We studied the neurotoxicity and pharmacokinetics of i.t. 4-hydroperoxycyclophosphamide (4-HC) in the rabbit and the activity of i.t. 4-HC in a VX2 rabbit model of leptomeningeal carcinomatosis to evaluate the potential use of 4-HC in the treatment of leptomeningeal tumors. Toxicity studies examined 4-HC doses ranging from 0.5 to 6.0 mumol administered by intraventricular injection weekly for 4 to 8 weeks. Clinical or histological neurotoxicity was not observed in rabbits treated with < 1.0 mumol 4-HC for 4 weeks. Clinical toxicity, characterized by lethargy, weight loss, seizures, or death, was apparent at doses > 2.0 mumol. Vasculitis of superficial arteries was observed in rabbits treated with > 1.0 mumol 4-HC. In cerebrospinal fluid pharmacokinetic studies, the mean drug half-life after intraventricular or intralumbar administration was 24.3 and 18.2 min. Regional inequities in drug exposure were apparent as area under the clearance curve values for cerebrospinal fluid distant from the injection site were lower than those of proximate sites (P < 0.001). Weekly intraventricular treatment of VX2 leptomeningeal tumor-bearing rabbits with 0.5 or 1.0 mumol of 4-HC resulted in an increased life span of 22.5 and 35%, respectively. These results indicate that i.t. 4-HC, at doses lower than those producing neurotoxicity in the rabbit, is effective treatment for VX2 leptomeningeal carcinomatosis.

Animals↗
PubMed1992

Optimization of busulfan dosage in children undergoing bone marrow transplantation: a pharmacokinetic study of dose escalation.

Busulfan (BU) is a widely used myeloablative and antineoplastic agent in clinical bone marrow transplantation (BMT). The lower incidence of BU-associated toxicities and lower therapeutic effectiveness in young children given BU doses based on body weight (ie, 16 mg/kg) is associated with altered pharmacokinetics of BU; the area under the curve (AUC) of BU concentration versus time is significantly less in these patients than those observed in older children and adults. To optimize BU dosage in young BMT recipients, we developed a dosage regimen based on body surface area (BSA) and determined BU pharmacokinetics and BU-associated toxicities. Seven children (median age, 3.9 years, range, 1.1 to 5.7) undergoing allogeneic or autologous BMT for leukemia received 40 mg/m2/dose BU every 6 hours for 16 doses; BU concentrations were measured in the plasma, and AUCs were determined for each patient after the first and 13th doses. Expressed as a function of body weight, the median BU dosage was 26.4 mg/kg (range, 24.3 to 28.2), a 60% increase over the BU dosage based on body weight. Four patients developed mucositis, and one of them also developed nonfatal hepatic veno-occlusive disease (VOD). No patients receiving 40 mg/m2 BU developed neurotoxicity (eg, seizures) or interstitial pneumonitis. Prompt and sustained engraftment was observed in the allogeneic BMT recipients, and late graft failure was not seen. The mean BU AUCs were 1,105 mumol/L.min (range, 790 to 2,080) after the first dose and 1,022 mumol/L.min (range, 632 to 1,860) after the 13th dose of BU, comparable to the AUCs in adults given 16 mg/kg of BU. These studies suggest that, in young children, BSA-based dosing of BU (40 mg/m2) provides drug exposures (AUCs) closer to adult values with acceptable toxicities and may improve therapeutic effects.

Bone Marrow Transplantation↗
PubMed1992

Effect of P-glycoprotein expression on the accumulation and cytotoxicity of topotecan (SK&F 104864), a new camptothecin analogue.

Topotecan (TPT, 9-dimethylaminomethyl-10-hydroxycamptothecin) is the first topoisomerase I-directed cytotoxic agent to enter clinical trials in the United States in two decades. The effect of P-glycoprotein (Pgp) overexpression on TPT cytotoxicity was examined in CHRC5 (colchicine-resistant) and AuxB1 (parental) Chinese hamster ovary cells. Examination of the IC50 values observed in colony-forming assays revealed that the CHRC5 cells were 15-fold (SD, +/- 3; n = 3) resistant to TPT after a 1-h exposure and 3.2-fold (SD, +/- 1.4; n = 4) resistant in continuous exposure experiments. Band depletion immunoblotting revealed that 4-fold higher concentrations of extracellular TPT were required to induce the formation of topo I-DNA complexes in CHRC5 cells as compared to AuxB1 cells. To assess the role of Pgp in this resistance, drug accumulation and cytotoxicity assays were repeated in the absence and presence of quinidine. Addition of quinidine enhanced TPT accumulation (measured by high-performance liquid chromatography) and diminished the IC50 for TPT to a greater extent in CHRC5 cells than in AuxB1 cells. To examine whether similar effects could be detected in Pgp-expressing human cells, MCF-7/Adriar breast cancer cells and KG1a human acute myelogenous leukemia cells were examined. Quinidine or verapamil enhanced TPT accumulation in both of these cell lines but had no effect in parental MCF-7 cells or a variety of human leukemia cell lines that do not overexpress Pgp. Cytotoxicity measurements performed by counting the number of surviving cells (MCF-7/Adriar) or employing a modified, highly stable tetrazolium dye reduction assay (leukemia cell lines) revealed that quinidine diminished the IC50 for TPT in the Pgp-overexpressing cell lines but not in the control lines. These results suggest that Pgp overexpression diminishes TPT accumulation and TPT cytotoxicity in hamster and human cells. It should be stressed, however, that these effects were substantially smaller than the effects of Pgp overexpression on the accumulation and cytotoxicity of the anthracycline daunorubicin and the epipodophyllotoxin etoposide in the same cell lines.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1992

Phase I and pharmacologic study of topotecan: a novel topoisomerase I inhibitor.

PURPOSE: A phase I and pharmacologic study was undertaken to determine the maximum-tolerated dose (MTD), describe the principal toxicities, and characterize the pharmacologic behavior of topotecan, which is a semisynthetic analog of camptothecin with broad preclinical antitumor activity and the first topoisomerase I-targeting agent to enter clinical development in the United States since studies of sodium camptothecin over 2 decades ago. PATIENTS AND METHODS: Thirty-minute infusions of topotecan were administered daily for 5 consecutive days every 3 weeks to patients with advanced solid malignancies at doses ranging from 0.5 to 2.5 mg/m2/d. RESULTS: At doses of 1.5 and 2.0 mg/m2, grade 3 and 4 neutropenia occurred in most courses; however, neutropenia was brief and rarely associated with fevers or treatment delays. Neutropenia was more severe in patients with extensive prior treatment than in minimally pretreated patients, but these differences were not substantial. At 2.5 mg/m2, topotecan induced profound and prolonged neutropenia that was frequently associated with fever and treatment delays in minimally pretreated patients. Topotecan also induced mild depressions in the hematocrit level in the majority of courses; however, precipitous drops requiring transfusional therapy occurred in 14% of courses and suggested a drug-induced hemolytic effect. Unlike sodium camptothecin, hemorrhagic cystitis was not observed. Thrombocytopenia, skin rash, diarrhea, and vomiting occurred infrequently and were modest in severity. Responses were observed in non-small-cell lung carcinoma and platinum-refractory ovarian carcinoma. Drug disposition in plasma was described by a biexponential model, with renal elimination accounting for 38.7% of drug disposition. Topotecan was rapidly hydrolyzed in vivo to a less active, open-ring form. CONCLUSIONS: Neutropenia is the dose-limiting toxicity, and 1.5 mg/m2 is the recommended starting dose of topotecan for both minimally and heavily pretreated patients in future phase II trials, with escalation to 2.0 mg/m2 if treatment is well tolerated. Non-small-cell lung and platinum-refractory ovarian carcinomas should be among those evaluated in phase II trials of topotecan.

Adult↗
PubMed1991

Phase I and pharmacokinetic study of hepsulfam (NSC 329680).

Hepsulfam (NSC 329680), a bifunctional alkylating agent structurally related to busulfan, has entered clinical trial based on its broader preclinical antitumor activity compared with that of busulfan and its i.v. formulation which may circumvent the many problems arising from the p.o. administration of busulfan, such as significant individual differences in bioavailability. In this Phase I study, 53 patients received 95 courses of hepsulfam at doses ranging from 30 to 480 mg/m2 administered i.v. over 30 min every 28 days. Hematological toxicity was dose limiting. Leukopenia and thrombocytopenia were dose related, delayed in onset, and sustained for long durations. Toxicity was cumulative in most patients receiving more than one course. This pattern of myelosuppression suggests that hepsulfam is cytotoxic to hematopoietic stem cells. Although hematological toxicity was not particularly severe during most courses, its lengthly duration precluded the prompt administration of subsequent courses. Minimal nonhematological effects were observed. Pharmacokinetic studies revealed that the clearance rate of hepsulfam is linear over the dose range studied and that its plasma disposition is biphasic with mean alpha and beta half-lives of 19 +/- 18 (SE) min and 337 +/- 248 (SE) min, respectively. The area under the plasma clearance curve correlated with the percentage of change in WBC using a sigmoidal Emax model and with the duration of thrombocytopenia in patients with hematological toxicity. Based on the protracted duration of the toxicity of multiple doses that were greater than 210 mg/m2, the recommended starting dose for Phase II trials is 210 mg/m2. However, these trials should be pursued with caution because of the protracted nature of hepsulfam's myelosuppression. Because hepsulfam produced minimal nonhematological toxicity, substantial dose escalation above 480 mg/m2 may be possible with hematopoietic stem cell support.

Adult↗
PubMed1991

Sequences of taxol and cisplatin: a phase I and pharmacologic study.

Untreated and minimally pretreated solid tumor patients received alternating sequences of taxol and cisplatin. Sequential dose escalation of each agent using taxol doses of 110 or 135 mg/m2 and cisplatin doses of 50 or 75 mg/m2 resulted in four dosage permutations that induced grades 3 and 4 neutropenia in 72% to 84% and 50% to 53% of courses, respectively. Neutropenia was brief, and hospitalization for neutropenia and fever was required in 13% to 24% of courses. However, further escalation of taxol to 170 or 200 mg/m2 induced grade 4 neutropenia in 79% to 82% of courses. At the highest taxol-cisplatin dose level (200 mg/m2 to 75 mg/m2), the mean neutrophil count nadir was 98/microL, and hospitalization for neutropenia and fever was required in 64% of courses. The sequence of cisplatin before taxol, which has less antitumor activity in vitro, induced more profound neutropenia than the alternate sequence. Pharmacologic studies indicated that this difference was probably due to 25% lower taxol clearance rates when cisplatin preceded taxol. Although neurotoxicity was initially thought to be a potentially serious effect of the combination, mild to modest neurotoxicity occurred in only 27% of patients. Adverse effects also included myalgias, alopecia, vomiting, diarrhea, bradycardia, and asymptomatic ventricular tachycardia. Objective responses were noted in melanoma, as well as non-small-cell lung, ovarian, breast, head and neck, colon, and pancreatic carcinomas. Based on these results, the sequence of taxol before cisplatin at doses of 135 and 75 mg/m2, respectively, is recommended for phase II/III trials, with escalation of taxol to 170 mg/m2 if treatment is well tolerated.

Adult↗
PubMed1990

Phase I and pharmacokinetic study of brequinar sodium (NSC 368390).

Brequinar sodium is a quinoline carboxylic acid derivative that has shown antitumor activity in a number of in vivo murine and human tumor xenograft models. Its mechanism of action is blockade of de novo pyrimidine biosynthesis by inhibition of dihydroorotic acid dehydrogenase. In vitro and in vivo studies demonstrate the superiority of prolonged drug exposure in achieving tumor growth inhibition. This phase I study evaluated the administration of brequinar sodium by short, daily i.v. infusion for 5 days repeated every 4 weeks. Fifty-four subjects were enrolled in the study and received drug in doses ranging from 36-300 mg/m2. The dose-limiting toxicities were mucositis and diffuse skin rash. Other toxicities included myelosuppression, nausea, vomiting, malaise, and burning at the infusion site. The maximum tolerated dose on the "daily times 5" schedule was 300 mg/m2. The recommended phase II dose is 250 mg/m2. Pharmacokinetic analysis of the day 1 drug clearance curves in 51 subjects showed slight nonlinearity in the relationship between dose and area under the clearance curve (AUC). The dose versus AUC relationship was well described using a Michaelis-Menten model of brequinar elimination kinetics with Vmax = 45 (micrograms/ml)/h and Km = 123 micrograms. Analysis of the day 5 drug clearance curves revealed a diminution in Vmax to 30 (micrograms/ml)/h. As a consequence of the reduction in Vmax brequinar plasma concentrations on day 5 were higher than predicted from day 1 drug kinetics. Pharmacodynamic analysis of the day 1 kinetic parameters and the toxicities occurring during the first cycle of drug therapy revealed significant correlations between mucositis and dose, AUC, and peak brequinar concentration; between leukopenia and AUC and peak drug concentration; and between thrombocytopenia and beta elimination rate.

Antineoplastic Agents↗
PubMed1990

Phase I study and pharmacodynamics of piroxantrone (NSC 349174), a new anthrapyrazole.

Piroxantrone (PRX, NSC 349174) is one of the first of a new class of intercalating agents, the anthrapyrazoles, to undergo clinical evaluation. Additionally, it is the first drug trial to prospectively test a new pharmacology-based dose escalation schema proposed for Phase I trials of anticancer compounds. In this Phase I trial, PRX was administered as a 1-h infusion every 3 weeks to patients with advanced cancer. Forty-four evaluable patients received 116 courses at doses ranging from 7.5 to 190 mg/m2. The dose-limiting toxicity was myelosuppression with leukopenia predominating. Nonhematological toxicities were minimal and consisted of nausea and vomiting, alopecia, mucositis, and phlebitis. Based on this trial, the maximum tolerated and recommended Phase II doses for PRX administered on this schedule are 190 and 150 mg/m2, respectively. PRX plasma elimination was rapid and best fit by a two-compartment model for 17 of 24 patients receiving greater than or equal to 90 mg/m2. The plasma clearance rate was 1290 +/- 484 ml/min (720 +/- 210 ml/min/m2) and did not vary with dose. The t1/2 alpha was 2.9 +/- 5.3 (SD) min and the t1/2 beta was 18.7 +/- 36.5 min. Area under the concentration versus time curve (AUC) at the maximal tolerated dose (MTD) was 435 mumol.min/liter, 40% higher than the predicted AUC from preclinical testing. The percentage decrease in WBC and neutrophil count was correlated with the AUC. The potential advantage of pharmacology-based dose escalation was limited in this study by assay insensitivity, extremely rapid plasma elimination, and the proximity of the starting dose to the dose where the target AUC was achieved and standard dose escalations were to begin. Consequently, there was no reduction in the number of dose escalations required to define the maximum tolerated dose. However, the practical aspects of this approach have been established and its use is recommended for further trials where detailed preclinical pharmacological studies are available.

Adult↗
PubMed1990

Busulfan disposition in children.

Children receive busulfan orally as part of myeloablative therapy before bone marrow transplantation for malignant and nonmalignant conditions. Children have been reported to have a low incidence of severe toxicity and significant rates of failure to achieve full engraftment. We evaluated the disposition of busulfan in children between 2 months and 3.6 years of age with lysosomal storage diseases, leukemia, and immunodeficiency disorders receiving oral doses of 1 or 2 mg/kg using a gas chromatographic assay. Peak concentrations were lower than those previously reported for adults, ranging from 1.4 to 5.2 mumol/L. The harmonic mean of the elimination half-life was 92 minutes, which is only slightly faster than that for adults (140 minutes). However, the area under the curve ranged from 400 to 1,000 (715 +/- 240) mumol.min/L, substantially lower than in adults receiving 1 mg/kg (range, 710 to 5,100 mumol.min/L; mean +/- SD, 2,180 +/- 1,200). The apparent volume of distribution (assuming complete bioavailability) ranged from 0.28 to 3.53 L/kg (1.42 +/- 0.86), which is more than twice that reported for adults (0.60 +/- 0.42). Busulfan clearance rate normalized to surface area is twice as high in children (200 +/- 100 mL/min/m2) as it is in adults (95 +/- 54 mL/min/m2). Alterations in bioavailability (absorption or first pass elimination) or in actual volume of distribution may account for these differences in drug disposition. The observed differences suggest the need for separate phase I dose escalation studies in children with accompanying pharmacokinetic assessment.

Administration, Oral↗
PubMed1990

Phase II trial of menogaril as initial chemotherapy for metastatic breast cancer.

Eighteen women with metastatic breast cancer previously untreated with chemotherapy were entered on a phase II trial of intravenous menogaril, a new anthracycline derivative. Treatment was given at 140 mg/m2 on days 1 and 8 of each 28 day cycle. The most common toxicities were leukopenia in all patients and burning and phlebitis at infusion sites in 72%. Serial assessment of cardiac function by resting and stress gated blood pool scans showed temporary decrements in ejection fraction in only 2 patients (11%). The response rate to the therapy was 19% [95% CI 0-38%] including 1 complete and 2 partial responses. The median time to relapse among responders was 6.5 months. Mean survival in all patients entered was 15.8 months from date of entry. Menogaril at this dose and schedule has modest activity as first line therapy for metastatic breast cancer but also has significant marrow and local toxicity.

Adult↗
PubMed1990

Preoperative assessment of malignant hepatic tumors.

Over a 31-month period, 100 patients with malignant hepatic tumors were preoperatively evaluated with three imaging techniques. The results of intravenously enhanced computed tomography (CT) scan, selective hepatic arterial contrast CT, and magnetic resonance imaging (MRI) were compared with operative findings. A total of 227 lesions were identified, with the sensitivity for tumor detection being arteriographically enhanced CT 94% (p less than 0.01), MRI 70%, and CT 66%. This advantage for arteriographically enhanced CT was most marked for lesions less than 1 cm in diameter (82% versus 20% for MRI and 5% for CT; p less than 0.01). Arteriographically enhanced CT was also most sensitive in assessing tumor margins. MRI was clearly superior to arteriographically enhanced CT or CT in detecting vascular involvement (85% versus 30% and 8%, respectively; p less than 0.01). No imaging technique was sensitive in determining extrahepatic involvement. Arteriographically enhanced CT was also best at predicting the operative procedure. The combination of arteriographically enhanced CT and MRI was the best predictor of true disease. We conclude that both arteriographically enhanced CT and MRI should be used for preoperative assessment of hepatic malignancies.

Adolescent↗
PubMed1989

Phase I trial of trimetrexate glucuronate on a five-day bolus schedule: clinical pharmacology and pharmacodynamics.

Trimetrexate glucuronate (TMTX), a nonclassical folate antagonist, has been evaluated clinically on several schedules. We have studied TMTX administered as an iv bolus for 5 consecutive days every 3 weeks in 35 patients with advanced solid tumors. Drug was given at doses ranging from 7.6 to 18.8 mg/m2. The maximal tolerated dose was 13.1 mg/m2 per day x 5 for patients without prior myelotoxic treatment and 7.6 mg/m2 per day x 5 for previously treated patients. Because of wide individual differences in drug tolerance, dose escalation in 25% increments is recommended for patients not experiencing toxic effects. The dose-limiting toxicity was neutropenia. Rash and mucositis were also significant. TMTX concentrations were measured 1 and 24 hours after each dose, and the data were fit by use of a one-compartment pharmacokinetic model. With this simplified sampling and modeling scheme, the mean total body clearance (+/- SD) of trimetrexate was 31 +/- 20 mL/min per m2 and the volume of distribution was 13 +/- 7 L/m2. Mean plasma concentrations 1 hour after a dose were 1.12, 2.43, 3.33, and 3.25 mumol/L at 7.6, 9.1, 10.9, and 13.1 mg/m2, respectively. The mean TMTX concentration (+/- SD) 24 hours after a dose was 114 +/- 87 nmol/L. The mean area under the concentration-versus-time curve at 13.1 mg/m2 was 2,266 mumol.min/L. The drug concentration 1 hour after the first dose and the area under the concentration-versus-time curve were highly correlated with leukopenia and thrombocytopenia (r = .6 and .65 and P = .0007 and .0001, respectively). The maximal tolerated dose on the daily x 5 schedule was 30% of the dose tolerated on an iv bolus schedule. The choice of drug schedule for clinical trials when murine and human pharmacokinetics differ is discussed. Phase II trials are under way with both the iv bolus and the daily x 5 schedules.

Adult↗
PubMed1989

Assessment of N-methylformamide (NMF) administered orally on a three times weekly schedule: a phase I study.

This phase I study was conducted to reevaluate the dose-limiting toxicities, maximum tolerated (MTD) and recommended phase II doses of oral NMF administered on a three times weekly schedule for 4 out of every 6 weeks. This schedule was based on the observation that prolonged administration of NMF was associated with the most efficacious antitumor activity in preclinical studies. Phase II trials that employed a starting dose of 800 mg/m2, determined in a previous phase I trial, were suspended because of frequent and severe toxicities. In the current study, a symptom complex characterized by nausea, vomiting, and malaise was the dose-limiting toxicity of oral NMF administered on this schedule. Other toxicities included hepatic enzyme elevations, mild myelosuppression, and worsening of preexistent toxic peripheral neuropathies. Of interest, three patients who were asymptomatic prior to treatment, rapidly developed symptoms of increased intracranial pressure after starting NMF; and, computerized tomographic brain scans revealed metastatic tumors with significant peritumoral edema. NMF was well tolerated at 600 mg/m2, however, an abrupt increase in toxicity resulted when the dose was increased to 700 mg/m2. Although NMF peak plasma concentrations (Cmax) and areas under the plasma disappearance curves (AUC) differed between the 600 and 700 mg/m2 dose levels, these differences were not striking, and similar NMF plasma concentrations and exposures were well tolerated during intravenous trials. Based on this study, the recommended phase II dose for oral NMF administered three times weekly for 4 of 6 weeks was 600 mg/m2.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1989

A phase I trial of trimetrexate glucuronate (NSC 352122) given every 3 weeks: clinical pharmacology and pharmacodynamics.

Trimetrexate glucuronate (TMTX), a non-classic folate antagonist, has been evaluated clinically on several schedules. We studied TMTX given as an i.v. bolus over 5-30 min every 3 weeks in 44 patients with advanced solid tumors; it was given at doses ranging from 20 to 275 mg/m2. The maximal tolerated dose (MTD) on this schedule is 220 mg/m2, which we also recommend as a starting dose for phase II studies in patients without extensive prior therapy. Because of wide individual differences in drug tolerance, dose escalation in 25% increments is recommended for non-toxic patients. The principal dose-limiting toxicity was myelosuppression, although in some patients a flu-like syndrome precluded dose escalation. Significant rash and mucositis also frequently occurred in toxic patients. TMTX plasma concentrations were measured after the first dose and the data were fit by two- or three-compartment mammillary pharmacokinetic models. The TMTX clearance rate was 36.5 +/- 21 ml/min per m2 and did not change with dose; non-linearities with increasing dose were apparent in the steady-state volume of distribution (Vss) and in the terminal disposition half-life (t1/2). The difference between pre-treatment and nadir leucocyte counts was correlated with TMTX dose (r = 0.58; P = 0.0006) and with the area under the concentration vs time curve (AUC) (r = 0.41; P = 0.02). Pre-treatment plasma albumin concentrations correlated weakly with the nadir white blood count (r = -0.36; P = 0.047). Optimal schedules for the administration of TMTX have not been established and phase II trials using both bolus and daily X 5 schedules are under way.

Adult↗
PubMed1989

Pharmacokinetics of busulfan: correlation with veno-occlusive disease in patients undergoing bone marrow transplantation.

Busulfan is an alkylating agent that is widely used in preparative regimens for bone marrow transplantation (BMT). We developed a high-performance liquid chromatographic (HPLC) assay for the determination of plasma busulfan concentrations in 30 patients who received oral doses of 1 mg/kg. Concentrations were fit by a one-compartment pharmacokinetic model with first-order absorption. The pattern of absorption and elimination varied widely between patients, with peak concentrations ranging from 1.2 to 10.4 mumol/l (mean, 4.25 +/- 2.49). The elimination half-life ranged from 58 to 433 min (harmonic mean, 140 min). The AUC contributed by a single oral dose ranged from 606 to 5,144 mumol-min/l (mean, 2,012 +/- 1,223). Patients were evaluated for the development of veno-occlusive disease (VOD), a treatment complication that occurs in 20% of patients undergoing BMT and causes 10% of transplantation-related deaths. All six patients who developed VOD had an AUC greater than the mean, and five of them had an AUC that was greater than 1 SD above the mean. The occurrence of VOD was highly correlated with an increased AUC (greater than 1 SD above the mean) (X2 = 18; P less than 0.0001). Using multivariate logistic regression, no other statistically significant pharmacokinetic predictor of VOD was found. The tenfold variability in the busulfan AUC and the statistical association of increased AUC with the development of VOD suggest a possible role for therapeutic monitoring in this setting.

Absorption↗
PubMed1989

A method for hepatic arterial perfusion studies in the rat.

The current model for selective hepatic arterial infusion therapy was evaluated for its suitability for short-term pharmacokinetic experiments. This preparation consists of selective cannulation of the common hepatic artery via the gastroduodenal artery of the rat. Radioactive microspheres were injected to determine hepatic or extrahepatic sites of perfusion. Radioactive microsphere determination of hepatic arterial flow and cardiac output were also performed. Our data indicate that at high flow rates (2 ml/min), significant loss of drug would occur due to retrograde flow. Modification of the model to include temporary proximal hepatic artery occlusion ensures hepatic delivery of greater than 95% of drug. Furthermore, temporary hepatic artery occlusion does not alter cardiac output or hepatic arterial blood flow. Selective hepatic arterial infusion in rats with synchronous temporary hepatic artery occlusion is an adequate model for short-term pharmacokinetic studies.

Animals↗
PubMed1988

Clinical and pharmacologic reappraisal of dichloromethotrexate.

Dichloromethotrexate (DCMTX) has been the subject of sporadic clinical development for the last 30 years. Although DCMTX was developed in hopes of discovering a more potent antifolate, the potential pharmacologic and toxicologic advantages of the analog have become of greater interest. This phase I and pharmacokinetic trial of DCMTX given on days 1, 8, and 15 every 28 days was undertaken to test these potential advantages. The maximally tolerated dose on this schedule was 980 mg/m2. Hepatic toxicity was dose limiting. Malaise, myelosuppression, and mucositis were also major toxic effects. The recommended dose for subsequent phase II studies of DCMTX administered on this schedule is 785 mg/m2 with a reduction to 625 mg/m2 for patients with a poor performance status or extensive prior therapy. Plasma disappearance curves for most patients were biphasic or triphasic, although several demonstrated more complex kinetic patterns that suggested significant enterohepatic circulation. The magnitude of the area under the plasma disappearance curve was related to the severity of DCMTX-induced hepatotoxicity. The elimination kinetics were linear, with a mean plasma clearance of 294 mL/min (range, 128-715). The pharmacokinetic behavior of DCMTX does not support its use over methotrexate in regional perfusion. DCMTX's primarily nonrenal elimination suggests that it may have an advantage over methotrexate when combined with nephrotoxic drugs such as cisplatin. However, there is little reason to commit major resources to further evaluation of DCMTX unless significant advantages in antineoplastic activity are identified.

Adult↗