Pharmacokinetics of Intraperitoneal Gemcitabine in a Rat Model

BACKGROUND

Gemcitabine (2'-2' difluorodeoxycytidine) has been shown to possess a broad spectrum of antitumor activity against various malignancies, particularly pancreatic carcinoma. For cancers occurring within the abdominal cavity, the advantage of intraperitoneal (i.p.) chemotherapy over intravenous (i.v.) chemotherapy is the high drug concentration that can be achieved locally. In addition, the cytotoxic effect of several anticancer agents can be enhanced by hyperthermia. Using a rat model, this study was designed to compare i.p. vs i.v. gemcitabine and to evaluate the effect of hyperthermia on i.p. gemcitabine.

METHODS

In the first phase of this study, 18 Sprague Dawley rats were given a single dose of gemcitabine then randomized into three groups according to dose and route of delivery of chemotherapy (12.5 mg/kg--i.v., 12.5 mg/kg--i.p. or 125 mg/kg--i.p.). In a separate experiment (phase 2), 12 Sprague Dawley rats were given a continuous i.p. perfusion of gemcitabine (12.5 mg/kg in 150 mL total perfusate) and randomized into two groups according to the temperature of the peritoneal perfusate (normothermic or hyperthermic). During the course of both experiments, peritoneal fluid and blood were sampled using a standardized protocol. At the end of the procedure the rats were sacrificed and all urine was extracted. Selected tissue samples were taken from rats in the second phase of the study. The concentration of gemcitabine in all samples was determined by high performance liquid chromatography (HPLC).

RESULTS

When gemcitabine was delivered at 12.5 mg/kg (phase 1) the area under the curve (AUC) was significantly higher with i.p. administration as compared to i.v. administration (P = 0.001). The AUC ratio (AUC peritoneal fluid/AUC plasma) was 12.5+/-3.2 for i.p. delivery as opposed to 0.2+/-0.2 for i.v. delivery (P = 0.0002). The AUC ratio for i.p. gemcitabine at 125 mg/kg was 26.8+/-5.8. Although there was no significant difference in drug concentrations between samples from the normothermic and hyperthermic groups, all tissue samples (except stomach) in the hyperthermic group exhibited increased gemcitabine concentrations.

CONCLUSION

These experiments demonstrated that the exposure of peritoneal surfaces to gemcitabine is significantly increased with i.p. gemcitabine. Intraabdominal hyperthermia had no significant effect on the pharmacokinetics of i.p. gemcitabine but there was evidence of increased absorption of gemcitabine in most intraabdominal tissues. Due to the likelihood of a high incidence of microscopic residual disease after resection of a pancreatic carcinoma, clinical studies to evaluate i.p. hyperthermic gemcitabine may be indicated.

Using pharmacologic data to plan clinical treatments for patients with peritoneal surface malignancy

The surfaces of the abdomen and pelvis are an important anatomic site for the dissemination of gastrointestinal and gynecologic malignancy. This transcoelomic spread of cancer cells gives rise to peritoneal carcinomatosis which, without special treatments, is a fatal manifestation of these diseases. In order to control peritoneal carcinomatosis cytoreductive surgery to remove gross disease is combined with perioperative intraperitoneal and perioperative intravenous chemotherapy to eradicate microscopic residual disease. Chemotherapy agents are selected to be administered by the intraperitoneal or intravenous route based on their pharmacologic properties. A peritoneal-plasma barrier which retards the clearance of high molecular weight chemotherapy from the peritoneal cavity results in a large exposure of small cancer nodules on abdominal and pelvic surfaces. Tissue penetration is facilitated by moderate hyperthermia (41-42 degrees C) of the intraperitoneal chemotherapy solution. A constant dose of chemotherapy agent and volume of carrier solution based on body surface area allows prediction of systemic drug exposure and systemic toxicity. Timing of the chemotherapy as a planned part of the surgical procedure to maximize exposure of all peritoneal surfaces is crucial to success.

A pharmacologic analysis of intraoperative intracavitary cancer chemotherapy with doxorubicin

PURPOSE

A pharmacologic analysis of intracavitary doxorubicin in the treatment of patients with intracavitary cancer dissemination was performed to further evaluate the possible benefits of this treatment modality.

METHODS

Twenty appendiceal malignancy patients with peritoneal carcinomatosis (PC), three appendiceal malignancy patients with direct extension into the pleural cavity, 20 patients with peritoneal mesothelioma and one patient with pleural mesothelioma were available for pharmacologic monitoring. After intraperitoneal or intrapleural administration of doxorubicin, plasma and peritoneal fluid samples were obtained at 15, 30, 45, 60 and 90 min in all patients. After intrapleural administration, plasma and pleural fluid samples were collected at similar intervals. Tumor and normal tissues were obtained when available. Doxorubicin concentrations were determined by high-performance liquid chromatography (HPLC).

RESULTS

Intraperitoneal doxorubicin showed a prolonged retention in the peritoneal cavity. Doxorubicin concentrations in tumor tissue were consistently elevated above intraperitoneal concentrations from 30 through 90 min. For appendiceal malignancy, the concentrations of doxorubicin were significantly higher in minimally aggressive mucinous tumors. Pleural chemotherapy solutions retained doxorubicin to a greater extent than peritoneal fluid.

CONCLUSIONS

Doxorubicin shows characteristics favorable for intracavitary administration with sequestration of doxorubicin in cancer nodules.

Comprehensive management of diffuse malignant peritoneal mesothelioma

AIMS

In the past, diffuse malignant peritoneal mesothelioma (DMPM) has been regarded as a terminal condition. The length of the survival was dependent upon the aggressive versus indolent biology of the neoplasm, nevertheless cure was not considered as a reasonable expectation and the overall median survival was approximately one year.

METHODS

A comprehensive literature review and a collection of pertinent data published on DMPM from the Washington Cancer Institute were used to construct this report.

RESULTS

Recent publications from Bethesda MD, New York, Milan Italy, Lyon France and Washington DC have shown a remarkable prolongation in the median survival of this group of patients with approximately half the patients alive at 5 years. These prolonged survivors were treated with an intensive local-regional treatment strategy that included cytoreductive surgery (CRS) with peritonectomy and hyperthermic intraoperative intraperitoneal chemotherapy (HIIC) and some patients with early postoperative intraperitoneal chemotherapy (EPIC). As larger numbers of patients have been treated, clinical features by which to select patients most likely to benefit from this approach have been identified. Also, as the experience in the management of patients receiving these treatments has increased, the morbidity and mortality associated with their management is being reduced.

CONCLUSIONS

A new standard of care involves surgical removal of large disease deposits combined with perioperative intraperitoneal chemotherapy. Knowledgeable management uses selection criteria and incurs low morbidity and mortality.

Hyperthermia modifies pharmacokinetics and tissue distribution of intraperitoneal melphalan in a rat model

BACKGROUND AND OBJECTIVES

Peritoneal surface malignancy is a common manifestation of failure of treatment for abdominal cancers. Best results of treatment have been achieved with complete cytoreduction followed by heated intraoperative chemotherapy. Melphalan is a chemotherapeutic agent that shows increased pharmacological activity with heat. But the combination of intraperitoneal administration and heat have never been tested for this drug. The purpose of this study was to evaluate the effect of hyperthermia on the pharmacokinetics and tissue distribution of intraperitoneal melphalan in a rodent model.

METHODS

Melphalan was given by the intraperitoneal route to 20 Sprague-Dawley rats at a dose of 12 mg/kg over 90 min. Rats were randomized into two groups according to the temperature of the peritoneal perfusate: group NT received normothermic (33.5 degrees C) melphalan; group HT received hyperthermic (42 degrees C) melphalan. During the course of intraperitoneal chemotherapy, peritoneal fluid and blood were sampled at 5, 15, 30, 60 and 90 min. At the end of procedure, the rats were killed and tissues samples (heart, liver, ileum, jejunum, colon, omentum, and abdominal wall) were collected. Concentrations of melphalan were determined in peritoneal fluid, plasma, and tissues by high-performance liquid chromatography.

RESULTS

The area under the curve (AUC) of peritoneal fluid melphalan was significantly lower in the HT group than in the NT group ( P=0.001), whereas no significant difference in plasma AUC was found. AUC ratios (AUC peritoneal fluid/AUC plasma) were 12.1 for the NT group and 12.3 for the HT group. The mean time to reach the plasma peak was shorter in the HT group than in the NT group ( P=0.004). The HT group exhibited increased melphalan concentrations in all intraabdominal tissues. These differences were significant for the ileum ( P=0.03) and jejunum ( P=0.04).

CONCLUSION

Hyperthermia affected the pharmacokinetics of intraperitoneal melphalan by decreasing the AUC of peritoneal fluid melphalan without increasing the plasma AUC. It increased intraabdominal tissue concentrations.

A comparison of hetastarch and peritoneal dialysis solution for intraperitoneal chemotherapy delivery

AIM

Intraperitoneal chemotherapy administration results in high drug concentration locally with low systemic toxicity. We compared the pharmacokinetics of paclitaxel infused intraperitoneally in two isotonic carrier solutions, 1.5% dextrose peritoneal dialysis solution (peritoneal dialysis solution) and hetastarch (6% hydroxyethyl starch), a high molecular weight solution.

METHODS

Twenty patients with peritoneal carcinomatosis were randomized into one of two groups to receive early postoperative intraperitoneal chemotherapy with paclitaxel for 5 consecutive days following cytoreductive surgery. One group (8 patients) received paclitaxel in one litre of peritoneal dialysis solution; the other group (12 patients) received paclitaxel in one litre of hetastarch. Samples of peritoneal fluid and venous blood were taken during the 23 h dwell time. Volumes of chemotherapy solution were recorded and concentrations of paclitaxel determined by high performance liquid chromatography.

RESULTS

Hetastarch clearance from the peritoneal cavity was reduced when compared to peritoneal dialysis solution. The mean volume of fluid remaining in the peritoneal cavity at 23 h was 900 ml +/-373.7 (SD) with hetastarch, and 285 ml (+/-157.5) with peritoneal dialysis solution (P=0.0022). The mean total amount of paclitaxel in the peritoneal cavity at 23 h was 2.597 mg (+/-1.57) with hetastarch and 0.772 mg (+/-0.667) with peritoneal dialysis solution (P=0.0152).

CONCLUSION

These data show that hetastarch increased the exposure of peritoneal surfaces to paclitaxel by increasing the volume of solution with no decrease in drug concentration. Residual tumour cells within the peritoneal cavity may show an increased response to paclitaxel with hetastarch as a carrier solution.

Pharmacokinetics of intraperitoneal oxaliplatin: experimental studies

BACKGROUND AND OBJECTIVES

Oxaliplatin is an antineoplastic platinum-based compound which has shown significant activity against advanced colon cancer. For cancers occurring within the abdominal cavity, the advantage of intraperitoneal chemotherapy is the high drug concentration that can be achieved locally with low systemic toxicity. Using a rat model, this study was designed to compare the pharmacokinetics and tissue absorption of intraperitoneal versus intravenous oxaliplatin.

METHODS

In the first phase of this study, fifteen Sprague Dawley rats were given a single dose of oxaliplatin then randomized into three groups according to dose and route of delivery (5 mg/kg intravenously, 5 mg/kg intraperitoneally, or 25 mg/kg intraperitoneally). In the second phase, 10 Sprague Dawley rats were given a continuous intraperitoneal perfusion of oxaliplatin (15 mg/kg) and randomized into two groups according to the temperature of the peritoneal perfusate (normothermic vs. hyperthermic). In both phases, peritoneal fluid and blood were sampled using a standardized protocol. At the end of each procedure the animals were sacrificed. Selected tissue samples were taken in the second phase only. For all samples, platinum levels were measured by direct current (d-c) plasma emission spectroscopy.

RESULTS

When oxaliplatin was delivered at 5 mg/kg the area under the curve (AUC) of the peritoneal fluid was 15-fold higher with intraperitoneal administration as compared to intravenous administration (P < 0.0001). The AUC ratio (AUC peritoneal fluid/AUC plasma) was 16 (+/- 5):1 for intraperitoneal delivery as opposed to 1:5 (+/- 2) for intravenous delivery (P = 0.0059). The AUC ratio for intraperitoneal oxaliplatin at 25 mg/kg was 17 (+/- 8):1. With the exception of the kidneys and the mesenteric nodes, tissue samples in the hyperthermic group exhibited increased oxaliplatin concentrations. These differences were not significant. For both groups colon tissues had the highest oxaliplatin concentrations.

CONCLUSIONS

These experiments demonstrated that the exposure of peritoneal surfaces to oxaliplatin was significantly increased with intraperitoneal administration. Although the differences were not statistically significant, hyperthermia did show a trend toward the enhancement of tissue absorption of oxaliplatin. The high concentration of drug observed in colonic tissues suggests the need for clinical studies to evaluate intraperitoneal oxaliplatin for microscopic residual tumor after surgical resection of colon malignancies.

Pharmacokinetics of intraperitoneal oxaliplatin: experimental studies

BACKGROUND AND OBJECTIVES

Oxaliplatin is an antineoplastic platinum-based compound which has shown significant activity against advanced colon cancer. For cancers occurring within the abdominal cavity, the advantage of intraperitoneal chemotherapy is the high drug concentration that can be achieved locally with low systemic toxicity. Using a rat model, this study was designed to compare the pharmacokinetics and tissue absorption of intraperitoneal versus intravenous oxaliplatin.

METHODS

In the first phase of this study, fifteen Sprague Dawley rats were given a single dose of oxaliplatin then randomized into three groups according to dose and route of delivery (5 mg/kg intravenously, 5 mg/kg intraperitoneally, or 25 mg/kg intraperitoneally). In the second phase, 10 Sprague Dawley rats were given a continuous intraperitoneal perfusion of oxaliplatin (15 mg/kg) and randomized into two groups according to the temperature of the peritoneal perfusate (normothermic vs. hyperthermic). In both phases, peritoneal fluid and blood were sampled using a standardized protocol. At the end of each procedure the animals were sacrificed. Selected tissue samples were taken in the second phase only. For all samples, platinum levels were measured by direct current (d-c) plasma emission spectroscopy.

RESULTS

When oxaliplatin was delivered at 5 mg/kg the area under the curve (AUC) of the peritoneal fluid was 15-fold higher with intraperitoneal administration as compared to intravenous administration (P < 0.0001). The AUC ratio (AUC peritoneal fluid/AUC plasma) was 16 (+/- 5):1 for intraperitoneal delivery as opposed to 1:5 (+/- 2) for intravenous delivery (P = 0.0059). The AUC ratio for intraperitoneal oxaliplatin at 25 mg/kg was 17 (+/- 8):1. With the exception of the kidneys and the mesenteric nodes, tissue samples in the hyperthermic group exhibited increased oxaliplatin concentrations. These differences were not significant. For both groups colon tissues had the highest oxaliplatin concentrations.

CONCLUSIONS

These experiments demonstrated that the exposure of peritoneal surfaces to oxaliplatin was significantly increased with intraperitoneal administration. Although the differences were not statistically significant, hyperthermia did show a trend toward the enhancement of tissue absorption of oxaliplatin. The high concentration of drug observed in colonic tissues suggests the need for clinical studies to evaluate intraperitoneal oxaliplatin for microscopic residual tumor after surgical resection of colon malignancies.

Impact of carrier solutions on pharmacokinetics of intraperitoneal chemotherapy

PURPOSE

In the treatment of gastrointestinal malignancies with dissemination to peritoneal surfaces the principal advantage of intraperitoneal chemotherapy over intravenous chemotherapy is the high drug concentration achieved locally with low systemic toxicity. This advantage can be optimized by maintaining a large area of contact between the chemotherapy solution and the surfaces within the abdomen and pelvis over a prolonged time period. Using a rat model we compared the pharmacokinetics of two drugs infused intraperitoneally, 5-fluorouracil and gemcitabine, in five different carrier solutions.

METHODS

A total of 120 Sprague Dawley rats were randomized into groups according to the carrier solution and the drug administered. Rats were given a single dose of intraperitoneal 5-fluorouracil (20 mg/kg) or gemcitabine (12.5 mg/kg) in 0.1 ml/g body weight of each carrier solution. The carrier solutions used varied in their tonicity (0.3%, 0.9% or 3% sodium chloride), or were isotonic and varied in molecular weight (0.9% sodium chloride, 4% icodextrin and 6% hetastarch). With the hypotonic, isotonic and hypertonic sodium chloride solutions, only 5-fluorouracil was used. Each group was further randomized according to the intraperitoneal dwell period (1, 3 or 6 h). At the end of the procedure the rats were killed, the peritoneal fluid was withdrawn completely and the blood was sampled using a standardized protocol. The volume of the peritoneal fluid was recorded, and the drug concentrations in the peritoneal fluid and plasma were determined by high-performance liquid chromatography.

RESULTS

Measurements of peritoneal fluid volume showed a more rapid clearance of hypotonic and isotonic sodium chloride solutions from the peritoneal cavity as compared to hypertonic sodium chloride and high molecular weight solutions. When comparing the remaining intraperitoneal volumes at 6 h, the differences were statistically significant for both 5-fluorouracil and gemcitabine when hetastarch (P < 0.0001 and P = 0.0004) and icodextrin (P = 0.002 and 0.008) were compared with isotonic sodium chloride solution. Similarly, there was a significant difference in the volumes recorded at 6 h when hypotonic (P < 0.0001) and isotonic sodium chloride solutions (P = 0.0002) were compared with hypertonic sodium chloride solution. The concentrations of chemotherapy in the different carrier solutions varied little. The total amount of drug in the peritoneal cavity decreased with all solutions and more quickly with 5-fluorouracil than with gemcitabine. There was a significant difference in the total intraperitoneal 5-fluorouracil between hypotonic and isotonic sodium chloride solutions at 1 h (P = 0.0003) and 3 h (P = 0.0043), as well as between the isotonic and hypertonic sodium chloride solutions at 1 h (P = 0.03) and 3 h (P < 0.0001). Similarly, there was a significant difference in the total peritoneal gemcitabine at 6 h between icodextrin and isotonic sodium chloride solution (P = 0.01) and between hetastarch and isotonic sodium chloride solution (P = 0.05). There were no significant differences in plasma 5-fluorouracil and plasma gemcitabine concentrations obtained with the five solutions.

CONCLUSIONS

These findings show that the clearance of 5-fluorouracil and gemcitabine from the peritoneal cavity can be significantly modified by varying the tonicity or the molecular weight of the carrier solution. Peritoneal fluid clearance was slower with hypertonic sodium chloride and high molecular weight solutions and this resulted in a reduced clearance of chemotherapy. By using a high molecular weight carrier solution the exposure of intraperitoneal cancer cells to gemcitabine was prolonged and drug availability at the peritoneal surface was increased. Similarly, by using a hypertonic carrier solution the exposure to 5-fluorouracil was prolonged and drug availability at the peritoneal surface was also increased.

Pharmacokinetics of intraperitoneal oxaliplatin: experimental studies

BACKGROUND AND OBJECTIVES

Oxaliplatin is an antineoplastic platinum-based compound which has shown significant activity against advanced colon cancer. For cancers occurring within the abdominal cavity, the advantage of intraperitoneal chemotherapy is the high drug concentration that can be achieved locally with low systemic toxicity. Using a rat model, this study was designed to compare the pharmacokinetics and tissue absorption of intraperitoneal versus intravenous oxaliplatin.

METHODS

In the first phase of this study, fifteen Sprague Dawley rats were given a single dose of oxaliplatin then randomized into three groups according to dose and route of delivery (5 mg/kg intravenously, 5 mg/kg intraperitoneally, or 25 mg/kg intraperitoneally). In the second phase, 10 Sprague Dawley rats were given a continuous intraperitoneal perfusion of oxaliplatin (15 mg/kg) and randomized into two groups according to the temperature of the peritoneal perfusate (normothermic vs. hyperthermic). In both phases, peritoneal fluid and blood were sampled using a standardized protocol. At the end of each procedure the animals were sacrificed. Selected tissue samples were taken in the second phase only. For all samples, platinum levels were measured by direct current (d-c) plasma emission spectroscopy.

RESULTS

When oxaliplatin was delivered at 5 mg/kg the area under the curve (AUC) of the peritoneal fluid was 15-fold higher with intraperitoneal administration as compared to intravenous administration (P < 0.0001). The AUC ratio (AUC peritoneal fluid/AUC plasma) was 16 (+/- 5):1 for intraperitoneal delivery as opposed to 1:5 (+/- 2) for intravenous delivery (P = 0.0059). The AUC ratio for intraperitoneal oxaliplatin at 25 mg/kg was 17 (+/- 8):1. With the exception of the kidneys and the mesenteric nodes, tissue samples in the hyperthermic group exhibited increased oxaliplatin concentrations. These differences were not significant. For both groups colon tissues had the highest oxaliplatin concentrations.

CONCLUSIONS

These experiments demonstrated that the exposure of peritoneal surfaces to oxaliplatin was significantly increased with intraperitoneal administration. Although the differences were not statistically significant, hyperthermia did show a trend toward the enhancement of tissue absorption of oxaliplatin. The high concentration of drug observed in colonic tissues suggests the need for clinical studies to evaluate intraperitoneal oxaliplatin for microscopic residual tumor after surgical resection of colon malignancies.

Multi-targeted antifolate (MTA): pharmacokinetics of intraperitoneal administration in a rat model

AIMS

LY 231514 or MTA is a multi-targeted antifolate which has been used as an anticancer drug. It is an analogue of folic acid which has shown antitumour activity against various malignancies, particularly mesothelioma and colon cancer. For cancers with peritoneal surfaces extension, the advantage of intraperitoneal chemotherapy over intravenous chemotherapy administration is the high drug concentration that can be achieved locally. Using a rat model, this study was designed to compare the pharmacokinetics and tissue adsorption of intraperitoneal vs intravenous MTA.

METHODS

Sprague-Dawley rats were randomized into three groups according to dose and route of delivery of chemotherapy (10 mg/kg: intravenous; 10 mg/kg: intraperitoneal; 100 mg/kg: intraperitoneal). During the course of the experiment, peritoneal fluid and blood were sampled using a standardized protocol. At the end of the 3 hour procedure the rats were sacrificed, all urine was extracted and selected tissue samples were taken. One additional rat was studied over a 6 hour period for each group. The concentration of MTA in all samples was determined by high performance liquid chromatography (HPLC).

RESULTS

When MTA was delivered at 10 mg/kg the area under the curve (AUC) of the peritoneal fluid was significantly higher with intraperitoneal administration (10 778 microg/mlxmin) compared to intravenous administration (454 microg/mlxmin) (P<0.0001). This represents a 24-fold increase in exposure for tissues at peritoneal surfaces after intraperitoneal administration. The AUC ratio (AUC peritoneal fluid/AUC plasma) was 40.8 for intraperitoneal delivery as opposed to 0.014 for intravenous delivery (P=0.0063). The AUC ratio for intraperitoneal MTA at 100 mg/kg was 19.2. The half-life of MTA in the peritoneal fluid after intraperitoneal infusion was approximately 2 hours. There was a significant difference in MTA concentration in the mesenteric nodes and the abdominal wall (P=0. 0036 and 0.0017) and in the kidneys (P=0.0122) when intraperitoneal and intravenous administration were compared. Other tissue samples did not demonstrate any difference in drug concentration.

CONCLUSION

These experiments demonstrated that the exposure of peritoneal surfaces to MTA is significantly increased with intraperitoneal MTA administration. Due to the high likelihood of microscopic residual disease after resection of intra-abdominal malignancies, clinical studies to evaluate intraperitoneal MTA may be indicated.

Lattice intrahepatic doxorubicin with and without in-flow occlusion: a pharmacokinetic study of direct liver injection

AIM

To assess possible improvements in drug delivery to unresectable liver tumours we investigated the pharmacokinetics of intrahepatic doxorubicin in the dog liver with and without inflow occlusion.

METHODS

Using a lattice template, doxorubicin was injected into 16 sites (over a 9 cm2 area) in each of three lobes of the liver for a total of 48 sites. The total doses of doxorubicin used were 4.8 mg and 96 mg (0.1 and 2 mg/site). Dogs with intravenous and intra-arterial delivery of the same total doses of doxorubicin were used as controls. Experiments using intrahepatic injection were performed with and without a 30 min occlusion of the hepatic artery, common bile duct and portal vein (inflow occlusion). The studies with vascular stasis were performed to determine if drug clearance from the injection sites and their plasma levels were reduced. Also, it was observed that blood and drug loss along the needle tract was reduced when inflow occlusion was used. Plasma and liver samples were harvested over a 90-min period and analysed by high pressure liquid chromatography (HPLC).

RESULTS

In plasma mean peak levels and mean area under the curve (AUC) were significantly lower with intrahepatic doxorubicin (P<0.05) than with intravenous or intra-atrial delivery. In the liver AUCintrahepatic/AUCintravenous ratios were 3.45 and 3.6 with 4.8 mg and 96 mg of doxorubicin respectively. The AUCintrahepatic/AUCintraarterial ratios were 1.97 and 1.65 respectively. The liver extraction ratio (AUCliver/AUCplasma) after intravenous administration with 4.8 mg and 96 mg of doxorubicin was 31.9 with both doses of doxorubicin. The corresponding extraction ratios were 107.6 and 51 for intra-arterial administration and 425.2 and 237.7 for intrahepatic administration for the two doses of doxorubicin. Intrahepatic injection with inflow occlusion minimized the leakage back along the needle-tracts. The liver visibly retained the injected drug more completely. However, there was a decrease in systemic clearance resulting in a reduction of the pharmacological advantage.

CONCLUSION

These results indicate that lattice-intrahepatic administration of doxorubicin into the liver using a lattice template was associated with a significant increase in local and decrease in systemic exposure as compared to intravenous or intra-arterial administration of the same doses. Simultaneous occlusion of arterial and portal venous inflow was not shown to improve regional drug delivery. These pharmacokinetic studies may constitute a basis for palliative treatment of liver tumours by lattice intralesional injection when these cancers are found to be unresectable at the time of exploratory surgery.

Heated intraoperative intraperitoneal mitomycin C and early postoperative intraperitoneal 5-fluorouracil: pharmacokinetic studies

PURPOSE

The purpose of this study was to report the pharmacokinetics of heated intraoperative intraperitoneal mitomycin C (MMC) and to analyze the impact of heat, extent of peritoneal resections, and effect of intraoperative hyperthermic chemotherapy on the pharmacological properties of the peritoneal plasma barrier.

METHODS

Sixty patients with peritoneal carcinomatosis were included in a phase I/II study combining cytoreductive surgery with 2 h of heated intraperitoneal mitomycin C in an intraoperative lavage technique and one cycle of early postoperative 5-fluorouracil (5-FU) given on postoperative days 1-5. Three pharmacokinetic analyses were performed: (1) pharmacokinetics of heated intraoperative intraperitoneal MMC was determined for 18 patients by sampling peritoneal fluid, plasma, and urine during the 2-h procedure; (2) impact of peritoneal resections on MMC pharmacokinetics was assessed by comparing a group of patients who underwent < or = 1 peritonectomy procedure (minimal surgery) to a group of patients who underwent > or = 2 peritonectomy procedures (extensive surgery), and (3) effects of heated intraoperative intraperitoneal chemotherapy on the pharmacokinetics of early postoperative intraperitoneal 5-FU by comparing a group of patients treated with heated intraoperative intraperitoneal MMC to a control group who did not receive heated intraoperative intraperitoneal chemotherapy.

RESULTS

The mean dose of heated intraoperative intraperitoneal MMC per patient was 22.5+/-7.1 mg (12.9+/-3.8 mg/m2). Drug absorption from perfusate was 14.3+/-2.7 mg. The mean aeras under the curve (AUC) for perfusate and plasma were, respectively, 340+/-138 and 15+/-4 microg/ml x min. The mean AUC peritoneal fluid/plasma ratio was 23.5+/-5.8. Patients who underwent extensive peritoneal resections exhibited a significantly (p = 0.037; Wilcoxon rank test) increased peak plasma concentration of MMC, a significantly (p = 0.029) increased AUC of plasma concentrations and a significantly (p = 0.034) decreased peritoneal fluid/plasma AUC ratio. Pharmacokinetic studies of early postoperative intraperitoneal 5-FU showed no significant difference in plasma AUC, perfusate AUC and AUC ratio between patients who received and those who did not receive heated intraoperative intraperitoneal MMC.

CONCLUSIONS

Heated intraoperative intraperitoneal chemotherapy achieves high peritoneal concentrations of MMC with limited systemic absorption. Systemic drug absorption during heated intraoperative intraperitoneal chemotherapy is increased when extensive peritoneal resections are performed, but such slight increases are unlikely to change the risk of systemic drug toxicities. Heated intraoperative intraperitoneal chemotherapy does not alter the pharmacokinetics of early postoperative intraperitoneal 5-FU.

Hyperthermic intraperitoneal doxorubicin: pharmacokinetics, metabolism, and tissue distribution in a rat model

BACKGROUND

The cytotoxic effect of several anticancer agents, including doxorubicin, can be enhanced by hyperthermia. The purpose of this study was to evaluate the effect of hyperthermia on the pharmacokinetics, metabolism, and tissue distribution of intraperitoneal (i.p.) doxorubicin in a rodent model.

METHODS

Doxorubicin was given i.p. to 20 Sprague-Dawley rats at a dose of 2 mg/kg over 60 min. Rats were randomized into two groups according to the temperature of the peritoneal perfusate: group NT received normothermic (37 degrees C) i.p. doxorubicin; group HT received hyperthermic (43 degrees C) i.p. doxorubicin. During the course of i.p. chemotherapy, peritoneal fluid and blood were sampled every 10 min. At the end of the procedure, rats were sacrificed and tissue samples (liver, spleen, small bowel, omentum, bladder, diaphragm, abdominal wall, heart) were collected. Concentrations of doxorubicin and its aglycone metabolites were determined in peritoneal fluid, plasma, and tissues by HPLC.

RESULTS

No significant differences in areas under the curve (AUC) of peritoneal fluid doxorubicin and plasma doxorubicin were found between group NT and group HT. AUC ratios (AUC peritoneal fluid/AUC blood) were 87.9 for group NT and 82.9 for group HT. Group HT exhibited increased doxorubicin concentrations for all intraabdominal tissues. These differences were significant for spleen (P = 0.03), small bowel (P = 0.03), and omentum (P = 0.03). Doxorubicin aglycone was detected in plasma of both groups within the first 10 min of the procedure. There was a significant (P < 0.001) increase in plasma aglycone AUC for group HT when compared with group NT. Group HT exhibited increased aglycone concentration for all tissues. This difference was significant for liver (P < 0.001) and bladder (P < 0.001).

CONCLUSION

Hyperthermia did not affect significantly the pharmacokinetics of i.p. doxorubicin. Tissue concentrations of doxorubicin in small bowel, omentum, and spleen were significantly increased when the drug was administered by hyperthermic i.p. perfusion. Hyperthermia increased significantly the doxorubicin aglycone concentrations in plasma, liver, and bladder.

Effects of intra-abdominal pressure on pharmacokinetics and tissue distribution of doxorubicin after intraperitoneal administration

Increased hydrostatic pressure in solid tumor nodules decreases the penetration of chemotherapy into cancerous tissue. This is true for both i.v. and i.p. chemotherapy. The purpose of this study was to determine the influence of increasing intra-abdominal pressures on the pharmacokinetics and tissue distribution of doxorubicin administered i.p. Four groups of 10 Sprague Dawley rats were given i.p. doxorubicin (4 mg/kg) during 60 min combined with no pressure (control), 10, 20 and 30 mm Hg pressures. During the course of i.p. chemotherapy, peritoneal fluid and blood were sampled. Two other groups of 10 rats received the same dose of i.p. doxorubicin during 10 min combined with no pressure and 30 mm Hg pressure. At the end of experiments animals were sacrificed and tissue samples were collected. Doxorubicin concentrations in peritoneal fluid, plasma and tissues were determined by HPLC. Pharmacokinetic studies showed that increased intra-abdominal pressures of 10, 20 and 30 mm Hg did not alter peritoneal fluid AUCs, the plasma AUCs and the peak ratios of i.p. doxorubicin when compared to the control group (no pressure). A subset analysis of high intra-abdominal pressure groups (20 and 30 mm Hg) versus control group showed statistically significant differences in peritoneal fluid AUCs, plasma AUCs and AUC (peritoneal fluid/plasma) ratios. For all groups, the highest tissue concentrations of doxorubicin were found in tissues associated with the parietal peritoneum: the bladder, the abdominal wall and the diaphragm. After 10 min of i.p. chemotherapy, the group treated with 30 mm Hg pressure showed a significant increase of doxorubicin concentrations in these tissues as compared to the control group. This significant increase of tissue doxorubicin concentrations was not found after 60 min of pressure with i.p. chemotherapy; prolonged intra-abdominal pressure was associated with a high incidence of intestinal ischemia. In conclusion, intra-abdominal pressure of 20 and 30 mm Hg significantly decreased the AUC ratios of i.p. doxorubicin but concomitantly increased tissue uptake of doxorubicin in bladder, diaphragm and abdominal wall during the first 10 min of i.p. administration. These findings may have significance in the design of improved strategies to increase tissue concentrations of chemotherapy delivered by an i.p. route.

Effect of intraperitoneal chemotherapy and fibrinolytic therapy on tumor implantation in wound sites

Failure of surgical treatment for gastrointestinal cancers is often caused by recurrence of the tumor in traumatized peritoneal surfaces. This study examined the effect of intraperitoneal administration of doxorubicin and recombinant tissue plasminogen activator (rt-PA), a fibrinolytic agent, on incidence and volume of postoperative tumor implants in peritoneal wounds. Prior to randomization, a surgical wound was created on the right parietal peritoneum of 110 BDIX rats and 6 x 10(5) DHD/K12 colon cancer cells were inoculated intraperitoneally (ip). The control group was given an intraperitoneal injection of saline. Five groups received 1 mg/kg of ip doxorubicin at different times postoperatively: at the end of surgery (D0), 3 hr after surgery (D + 3), postoperative day 1 (D1), postoperative day 3 (D3), and postoperative day 7 (D7). In a second set of experiments, five groups of rats received, in addition to postoperative doxorubicin, 5 mg/kg of intraoperative ip rt-PA. Incidence and volume of tumor implants in peritoneal wounds were assessed for each group 20 days after the tumor inoculation. All rats of the control group (incidence = 100%) developed tumor implants in peritoneal wounds. Mean (SD) volume was 16.2 (4.7) mm3. When administered at D0, D + 3, and D1 intraperitoneal doxorubicin reduced significantly the incidence and volume of tumor implants in wounds. Postoperative administration of doxorubicin at D3 and D7 did not affect significantly the incidence and the volume of tumor implants in peritoneal wounds. When rt-PA was administered intraoperatively, ip injection of doxorubicin at any postoperative timing decreased significantly the incidence and volume of tumor implants. In conclusion, ip doxorubicin administered before postoperative D3 may act on tumor cell implanted in peritoneal wounds. Delayed (D3, D7) ip administration of doxorubicin does not prevent the development of tumor implants in peritoneal wounds. Intraoperative administration of rt-PA may significantly increase the efficacy of delayed ip chemotherapy.

Pharmacokinetics of the peritoneal-plasma barrier after systemic mitomycin C administration

The peritoneal plasma barrier (PPB) is a pharmacologic entity of importance for treatment planning in patients with malignant tumors confined to the abdominal cavity. We have examined the pharmacokinetics of the PPB by sampling abdominal fluid following intravenous mitomycin C (MMC) administration. The study included 15 cycles of treatment in seven patients with peritoneal carcinomatosis from colorectal cancer. Five patients were studied twice and one patient was studied three times for a total of 15 cycles. Patients were treated with intraperitoneal 5-fluorouracil (5-FU) at 20 mg/m2 in 11 of fluid. Between 250 and 500 ml of ascites remained after the 23 hour intraperitoneal dwell. On day 3, MMC (12 mg/m2) was administered intravenously as a 2-hour continuous infusion in 200 ml of dextrose solution. The concentration of MMC was determined in plasma, peritoneal fluid, and urine by high performance liquid chromatolography (HPLC) at frequent intervals for 8 hours. The area under the curve (AUC) for plasma as related to peritoneal fluid was three times greater for plasma in one cycle, two times greater for plasma in three cycles, 1.5 times greater for plasma in five cycles, and the same in six cycles. AUC ratios showed a correlation with the extent of peritoneal stripping at the prior surgical procedure 6 weeks to 14 weeks previously. We conclude that malignant ascites may be less exposed to chemotherapy than systemic tumor nodules when the intravenous route of drug administration is used. This inadequacy is even more pronounced in patients who have had extensive abdominal surgery.

Surgically directed chemotherapy: heated intraperitoneal lavage with mitomycin C

This chapter reported the pharmacokinetics and the toxicities of mitomycin-c (MMC) when administered as a hyperthermic intraperitoneal lavage after surgical resection of advanced primary or recurrent gastrointestinal cancer. Pharmacologic studies were performed in 10 patients and all adverse reactions were recorded in 20 patients. These 20 patients had advanced gastrointestinal malignancies with peritoneal carcinomatosis and underwent cytoreductive surgery prior to intraperitoneal lavage. Heated (42 degrees C) intraperitoneal mitomycin C was used in a lavage technique with 30 mg/3 1 of drug for 2 hours. The fluid was distributed throughout the abdominal cavity by vigorous external massage of the abdominal wall. This resulted in approximately 70 percent (21 mg) drug absorption from the perfusate. Urine output of MMC averaged 2.5 mg during the 2 hour procedure. Median peak blood levels of 0.25 micrograms/ml (range 0.11-0.41 micrograms/ml) were observed at 45-60 minutes into the procedure. Morbidity was low and was mainly related to the surgical procedures (prolonged ileus, postoperative fistulas) with mild to moderate drug-related myelosuppression. This new method of delivery of MMC and 5-FU should be explored in phase II clinical trials.

Hyperthermic intraoperative intreperitoneal chemotherapy (HIIC) with mitomycin C

Dedrick et al. published a mathematical model in 1978 that described the theoretical rationale for in- traperitoneal administration of chemotherapeutic agents.' Numerous authors have provided substantial clinical and experimental evidence supporting Dedrick's model. Lukas et al.' and Torres et al.' have de- scribed the pharmacokinetics involved in the transport of drugs from the peritoneal cavity into the portal and systemic circulation. These investigations and others gave birth to the pharmacologic concept known as the peritoneal plasma barrier (PPB). The PPB has been described as a complex diffusion barrier, consisting of the endothelium, the mesothelium, and the intervening interstitium, along with the fluid in the blood and the dialysate.t This physiologic barrier limits the resorption of hydrophilic drugs such as mitomycinC, doxoru- bicin, and cisplatin from the peritoneal cavity into the blood.

Pharmacokinetic studies of intraaortic stop-flow infusion with 14C-labeled mitomycin C

This pharmacokinetic study attempted to improve the exposure of gastrointestinal tract tissues to chemotherapy by increasing the transit time of a first pass of a drug through the vascular system. Bolus infusion of 9 mg mitomycin (MMC) mixed with 1 mg of MMC labeled by 50 microCi of 14C was performed in 18 mongrel dogs. Pharmacokinetics of MMC in peripheral, portal, and aortic blood were studied under different types of major vessel occlusion. Three dogs with intravenous infusion constituted a control group. In 15 dogs MMC was infused intraaortically with the catheter's tip at the level of the celiac and superior mesenteric artery. Vascular flow was controlled in four different ways for 30 min: Type I-Type IV. In Type IV the abdominal aorta and vena cava inferior were occluded after surgical exclusion of all nongastrointestinal branches of aorta. Blood samples were obtained during a 90-min period. After solubilizing the samples, 14C-labeled MMC activity was counted by a scintillation counter. For stop-flow infusion Type I, II, III, and IV, area under the curve (AUC) ratios for portal blood versus systemic circulation were 1.6:1, 2.9:1, 2.9:1, and 8.8:1, respectively (statistically significant for Types II, III, and IV). The highest value of AUC, peak MMC concentration, and lowest clearance in portal blood were achieved in SFI Type IV. Exposure to MMC was the greatest with SFI Type IV, making this type of aortic stop-flow infusion the most favorable mode of drug administration from a pharmacokinetic perspective.

Intraaortic stop-flow infusion: pharmacokinetic feasibility study of regional chemotherapy for unresectable gastrointestinal cancers

BACKGROUND

This study attempted to increase the exposure of gastrointestinal tract tissues to chemotherapy by prolonging the first pass of intraaortically administered drug by temporary occlusion of vascular structures.

METHODS

Bolus infusion of 14C-labeled mitomycin C (MMC) mixed with unlabeled MMC was performed in dogs. Distribution of MMC in gastrointestinal tract tissues was studied under different types of major vessel occlusion. Three dogs with intravenous infusion constituted the control group. Vascular flow was controlled in four ways for 30 min: type I--stop-flow infusion (SFI) with clamping of the abdominal aorta above the celiac and below inferior mesenteric artery; type II--with additional clamping of the inferior vena cava above the diaphragm; type III with additional clamping of the portal vein in the hepatoduodenal ligament; and type IV--with surgical exclusion of nongastrointestinal branches of the aorta in addition to type II clamping.

RESULTS

Type II and IV produced a 3-10-fold increase in exposure to MMC of major gastrointestinal tissues as compared with intravenous infusion. Area under the curve ratios with type IV were most prominent in the following tissues: stomach, pancreas, liver, and mesenteric lymph node.

CONCLUSION

Access of MMC to several gastrointestinal tissues was increased through SFI. Type IV infusion was the most effective. Tissue exposure to MMC was especially advantageous for stomach, pancreas, liver, and mesenteric lymph node.

Synthesis and properties of some peptide analogues of actinomycin D

Analogues of actinomycin D (AMD) were synthesized in which amino acid replacements were made at various sites in the peptide moieties. These include (i) replacement of both N-methylvalines by N-methylleucine, (ii) replacement of both sarcosines by N-[2-(methoxycarbonyl)ethyl]glycine, and (iii) replacement of one or both D-valines by D-threonine. The purpose of replacements ii and iii was to ascertain the effect upon biological activity of introducing a new side chain which could be functionalized to allow the attachment of carrier molecules such as antibodies. NMR data indicated that none of the analogues had solution conformations significantly different from that of AMD. Difference spectra with DNA revealed that replacement i enhanced binding while the other analogues bound less strongly to DNA. All the analogues had lower antimicrobial activities than AMD. In contrast, 5,5'-(MeLeu)2AMD displayed in vitro antitumor activity comparable with that of AMD at approximately 100-fold lower concentrations.

Synthesis of an actinomycin-related peptide lactone from the corresponding cyclic pentapeptide by N,O-acyl shift

The N,O-acyl shift was investigated as a method for the synthesis of an O-peptide or peptide lactone from a linear or cyclic peptide respectively. Protected derivatives of glycyl-L-threonine could be converted to O-peptides by the action of HCl/dioxane at room temperature and N-acylated under conditions which precluded a reverse O,N-acyl shift. For effecting N,O-acyl shift in cyclo(Thr-D-Val-Pro-Sar-MeAla) this reagent was unsatisfactory and p-toluenesulfonic acid in dioxane at 80 degrees was used instead. The resulting crystalline peptide lactone p-toluenesulfonate salt was N-acylated with 3-benzyloxy-4-methyl-2-nitrobenzoyl chloride to afford a known intermediate in the synthesis of 5,5'-MeAla actinomycin D. This approach constitutes a novel synthetic route to actinomycins and potentially to other peptide lactone antibiotics.

Slow O,N-acyl shift in an actinomycin-related peptide lactone

The pentapeptide lactone Cbz-(Thr-D-Val-Pro-Sar-MeAla-) was synthesized in order to observe the behavior of the unprotected lactone resulting from its hydrogenolytic deprotection. Closely related peptide lactones have been reported as intermediates in total syntheses of actinomycin D and its analogues, despite the fact that unprotected and unprotonated O-peptides of serine and threonine are known to undergo rapid O,N-acyl shift. In the present study the peptide lactone was seen to undergo a slow O,N-acyl shift, in a matter of hours, to the known cyclic pentapeptide. This contrasted with the rapid rearrangement of a model O-peptide, O-hippuryl-L-threonine methyl ester. This slowness of an O,N-acyl shift in a cyclic system presumably results from higher energy barriers of conformational origin. It explains the suitability of unprotected peptide lactones for the syntheses of actinomycins and other peptide lactone antibiotics which have appeared in the literature.