Hypotensive mechanisms of amifostine

A novel approach for the prevention of ionizing radiation-induced bone loss using a designer multifunctional cerium oxide nanozyme

The disability, mortality and costs due to ionizing radiation (IR)-induced osteoporotic bone fractures are substantial and no effective therapy exists. Ionizing radiation increases cellular oxidative damage, causing an imbalance in bone turnover that is primarily driven via heightened activity of the bone-resorbing osteoclast. We demonstrate that rats exposed to sublethal levels of IR develop fragile, osteoporotic bone. At reactive surface sites, cerium ions have the ability to easily undergo redox cycling: drastically adjusting their electronic configurations and versatile catalytic activities. These properties make cerium oxide nanomaterials fascinating. We show that an engineered artificial nanozyme composed of cerium oxide, and designed to possess a higher fraction of trivalent (Ce³⁺) surface sites, mitigates the IR-induced loss in bone area, bone architecture, and strength. These investigations also demonstrate that our nanozyme furnishes several mechanistic avenues of protection and selectively targets highly damaging reactive oxygen species, protecting the rats against IR-induced DNA damage, cellular senescence, and elevated osteoclastic activity in vitro and in vivo. Further, we reveal that our nanozyme is a previously unreported key regulator of osteoclast formation derived from macrophages while also directly targeting bone progenitor cells, favoring new bone formation despite its exposure to harmful levels of IR in vitro. These findings open a new approach for the specific prevention of IR-induced bone loss using synthesis-mediated designer multifunctional nanomaterials.

Alterations in Tissue Metabolite Profiles with Amifostine-Prophylaxed Mice Exposed to Gamma Radiation

Acute exposure to high-dose ionizing irradiation has the potential to severely injure the hematopoietic system and its capacity to produce vital blood cells that innately serve to ward off infections and excessive bleeding. Developing a medical radiation countermeasure that can protect individuals from the damaging effects of irradiation remains a significant, unmet need and an area of great public health interest and concern. Despite significant advancements in the field of radiation countermeasure development to find a nontoxic and effective prophylactic agent for acute radiation syndrome, no such drug has yet been approved by the Food and Drug Administration. This study focuses on examining the metabolic corrections elicited by amifostine, a potent radioprotector, on tissues of vital body organs, such as the heart, spleen, and kidney. Our findings indicate that prophylaxis with this drug offers significant protection against potentially lethal radiation injury, in part, by correction of radiation-induced metabolic pathway perturbations.

The efficacy and safety of amifostine for the acute radiation syndrome

Introduction: A radiation countermeasure that can be used prior to radiation exposure to protect the population from the harmful effects of radiation exposure remains a major unmet medical need and is recognized as an important area for research. Despite substantial advances in the research and development for finding nontoxic, safe, and effective prophylactic countermeasures for the acute radiation syndrome (ARS), no such agent has been approved by the United States Food and Drug Administration (FDA). Area covered: Despite the progress made to improve the effectiveness of amifostine as a radioprotector for ARS, none of the strategies have resolved the issue of its toxicity/side effects. Thus, the FDA has approved amifostine for limited clinical indications, but not for non-clinical uses. This article reviews recent strategies and progress that have been made to move forward this potentially useful countermeasure for ARS. Expert opinion: Although the recent investigations have been promising for fielding safe and effective radiation countermeasures, additional work is needed to improve and advance drug design and delivery strategies to get FDA approval for broadened, non-clinical use of amifostine during a radiological/nuclear scenario.

Design and synthesis a mitochondria-targeted dihydronicotinamide as radioprotector

Radiation-induced damage to the mitochondrial macromolecules and electron transfer chain (ETC), causing the generation of primary and secondary reactive oxygen (ROS) species. The continuous ROS production after radiation will trigger cell oxidative stress and ROS-mediated nucleus apoptosis and autophagy signaling pathways. Scavenging radiation-induced ROS effectively can help mitochondria to maintain their physiological function and relief cells from oxidative stress. Nicotinamide is a critical endogenous antioxidant helping to neutralize ROS in vivo. In this study, we designed and synthetized a novel mitochondrial-targeted dihydronicotinamide (Mito-N) with the help of mitochondrial membrane potential to enter the mitochondria and scavenge ROS. According to experiment results, Mito-N significantly increased cell viability by 30.75% by neutralizing the accumulated ROS and resisting DNA strands breaks after irradiation. Furthermore, the mice survival rate also improved with the treatment of Mito-N, by effectively ameliorating the hematopoietic system infliction under lethal dose irradiation.

Localized Delivery of Amifostine Enhances Salivary Gland Radioprotection

Radiotherapy for head and neck cancers commonly causes damage to salivary gland tissue, resulting in xerostomia (dry mouth) and numerous adverse medical and quality-of-life issues. Amifostine is the only Food and Drug Administration-approved radioprotective drug used clinically to prevent xerostomia. However, systemic administration of amifostine is limited by severe side effects, including rapid decrease in blood pressure (hypotension), nausea, and a narrow therapeutic window. In this study, we demonstrate that retroductal delivery of amifostine and its active metabolite, WR-1065, to murine submandibular glands prior to a single radiation dose of 15 Gy maintained gland function and significantly increased acinar cell survival. Furthermore, in vivo stimulated saliva secretion was maintained in retrograde-treated groups at levels significantly higher than irradiated-only and systemically treated groups. In contrast to intravenous injections, retroductal delivery of WR-1065 or amifostine significantly attenuated hypotension. We conclude that localized delivery to salivary glands markedly improves radioprotection at the cellular level, as well as mitigates the adverse side effects associated with systemic administration. These results support the further development of a localized delivery system that would be compatible with the fractionated dose regimen used clinically.

Novel Formulation Strategy to Improve the Feasibility of Amifostine Administration

PURPOSE

Amifostine (AMF), a radioprotectant, is FDA-approved for intravenous administration in cancer patients receiving radiation therapy (XRT). Unfortunately, it remains clinically underutilized due to adverse side effects. The purpose of this study is to define the pharmacokinetic profile of an oral AMF formulation potentially capable of reducing side effects and increasing clinical feasibility.

METHODS

Calvarial osteoblasts were radiated under three conditions: no drug, AMF, and WR-1065 (active metabolite). Osteogenic potential of cells was measured using alkaline phosphatase staining. Next, rats were given AMF intravenously or directly into the jejunum, and pharmacokinetic profiles were evaluated. Finally, rats were given AMF orally or subcutaneously, and blood samples were analyzed for pharmacokinetics.

RESULTS

WR-1065 preserved osteogenic potential of calvarial osteoblasts after XRT to a greater degree than AMF. Direct jejunal AMF administration incurred a systemic bioavailability of 61.5%. Subcutaneously administrated AMF yielded higher systemic levels, a more rapid peak exposure (0.438 vs. 0.875 h), and greater total systemic exposure of WR-1065 (116,756 vs. 16,874 ng*hr/ml) compared to orally administered AMF.

CONCLUSIONS

Orally administered AMF achieves a similar systemic bioavailability and decreased peak plasma level of WR-1065 compared to intravenously administered AMF, suggesting oral AMF formulations maintain radioprotective efficacy without causing onerous side effects, and are clinically feasible.

Evaluation of a method for measuring the radioprotective metabolite WR-1065 in plasma using chemical derivatization combined with UHPLC-MS/MS

Hypotension is the dose-limiting side effect of the radio-protective drug Amifostine and results from relaxation of the vascular smooth muscle, which is directly mediated by the active metabolite, WR-1065, of Amifostine. The route of administration (currently FDA-approved only for intravenous administration) and the rapid metabolic conversion of Amifostine combine to yield high systemic levels of WR-1065 and facilitate the onset of hypotension. Research efforts aiming to optimize the delivery of WR-1065 to maintain efficacy while reducing its peak, systemic concentration below levels that induce hypotension are underway. To fully characterize the effect of reduced dose levels and alternative routes of administration of Amifostine on systemic WR-1065 concentrations, improved analytical techniques are needed. We have developed and evaluated a highly sensitive method for measuring WR-1065 in rat plasma that employs chemical derivatization, protein precipitation and UPLC-MS/MS analysis. The method exhibits a limit of quantification (LOQ) of 7.4 nM in plasma, which is a significant improvement over conventional approaches that utilize LC-electrochemical detection (ECD) (LOQ 150 nM or higher). The method was assessed in a pharmacokinetics study in rats administered Amifostine intravenously and via direct jejunal injection (10 mg/kg each route). The bioavailability of WR-1065 was 61.5% after direct jejunal injection indicating rapid conversion and absorption of the metabolite in the intestinal tract. This demonstrates that an oral formulation of Amifostine designed for site-specific release of the drug in the upper GI tract can deliver systemic absorption/conversion to WR-1065, provided that the formulation protects the therapeutic from gastric decomposition in the stomach.

Synthesis and Radioprotective Activity of Mitochondria Targeted Dihydropyridines In Vitro

The radiation-induced damage to mitochondrial oxidative respiratory chain could lead to generating of superoxide anions (O²⁻) and secondary reactive oxygen species (ROS), which are the major resources of continuous ROS production after radiation. Scavenging radiation-induced ROS effectively can help mitochondria to maintain their physiological function and relief cells from oxidative stress. Dihydropyridines (DHPs) are biomimetic hydrogen sources that could protect cells against radiation damage. In this study, we designed and synthetized three novel mitochondrial-targeted dihydropyridines (Mito-DHPs) that utilize the mitochondrial membrane potential to enter the organelle and scavenge ROS. MitoTracker confirmed Mito-DHPs accumulation in mitochondria, and the DCFH-DA assay demonstrated effective ROS scavenging activity. In addition, the γ-H2AX and comet assay demonstrated the ability of Mito-DHPs to protect against both radiation and ROS-induced DNA strand breaks. Furthermore, Mito-DHP1 proved to be non-toxic and displayed significant radioprotection activity (p < 0.05) in vitro. Mito-DHPs are therefore promising antioxidants that could penetrate the membrane of mitochondria, scavenge excessive ROS, and protect cells against radiation-induced oxidative damage.

Effect of amifostine, a radiation-protecting drug, on oxygen concentration in tissue measured by EPR oximetry and imaging

Effect of amifostine, a radiation-protecting drug, on muscle tissue partial pressure of oxygen was investigated by electron paramagnetic resonance spectroscopy and imaging. When amifostine was administered intraperitoneally or intravenously to mice, the linewidth of the electron paramagnetic resonance spectra of the lithium octa-n-butoxy-substituted naphthalocyanine implanted in the mouse leg muscle decreased. Electron paramagnetic resonance oximetry using a lithium octa-n-butoxy-substituted naphthalocyanine probe and electron paramagnetic resonance oxygen mapping using a triarylmethyl radical paramagnetic probe was useful to quantify pressure of oxygen in the tissues of living mice. The result of electron paramagnetic resonance oximetric imaging showed that administration of amifostine could decrease pressure of oxygen in the muscle and also tumor tissues. This finding suggests that lowering pressure of oxygen in tissues might contribute in part to the radioprotection of amifostine.

Sustained-release microspheres of amifostine for improved radio-protection, patient compliance, and reduced side effects

A biweekly administration of sustained-release microsphere dosage form of amifostine, a radioprotective drug used in radiotherapy, was performed to examine the feasibility to minimize injection frequency and blood concentration-associated side effects. Model animal trials indicated that this subcutaneously injecting microspheres, 50-100 μm in diameter, achieved bi-weekly prolonged radio-protective efficacy and, at the same time, significantly reduced skin irritation than the solution form of amifostine given by the same administration route. In addition, the hypertension associated with blood concentration of amifostine was not observed in the drug-treated rats. The animals given the amifostine microspheres and amifostine showed significantly differences in white blood cell, red blood cell, hematocrit, hemoglobin and spleen tissue histopathology after exposed under a cobalt-60 γ-radiation at a dose rate of 1.0 Gy/min for 6 min. The in vitro release profile of amifostine from the micropsheres showed a minor initial burst (less than 20% of total drug loading in the first day of administration), consisting with the side effects observations. The results suggest that amifostine encapsulated in sustained-release microspheres may be an ideal dosage form for prolonged radio-protective efficacy and improved patient compliance.

Fruit Extract of Aegle marmelos Protects Mice Against Radiation-Induced Lethality

The radioprotective effect of a hydroalcoholic extracted material from the fruit of Aegle marmelos (AME) was studied in mice exposed to different doses of γ radiation. The optimum dose for radioprotection was determined by administering 0, 5, 10, 20, 40, or 80 mg/kg body weight of AME intraperitoneally (ip) once daily, consecutively for 5 days before exposure to 10 Gy of γ radiation. A total of 20 mg/kg of AME for 5 consecutive days before irradiation was found to afford maximum protection as evidenced by the highest number of survivors after 30 days postirradiation. Animals from all groups were monitored for 30 days postirradiation for development of symptoms of radiation sickness and mortality. Treatment of mice with AME before exposure to different doses of γ radiation reduced the severity of symptoms of radiation sickness and mortality with all exposure doses. This was accompanied by an increase in number of survivors in the AME + irradiation group when compared with the concurrent sterile physiological saline (SPS) + irradiation group. AME pretreatment protected mice against the gastrointestinal as well as bone marrow deaths, as evidenced by the greater number of survivors on day 10 or 30, respectively. LD50/30 was found to be 8.2 Gy for the SPS + irradiation group, while it was 8.8 Gy for AME + irradiation. The dose-reduction factor (DRF) was found to be 1.1 for AME + irradiation group. The acute toxicity study of AME showed that it was nontoxic up to a dose of 6 g/kg body weight, the highest drug dose that could be administered. Irradiation of animals resulted in a dose-dependent elevation in lipid peroxidation in liver, kidney, stomach, and intestine of mice. Conversely, GSH concentration declined in a dose-dependent manner. Treatment of animals with AME before irradiation caused a significant decrease in the lipid peroxidation accompanied by a significant elevation in the GSH concentration in liver, kidney, stomach, and intestine of mice determined at 31 days postirradiation.

Role of glutamate and serotonin on the hypoxic ventilatory response in high-altitude-adapted plateau Pika

The highland "plateau Pika" is considered to be adapted to chronic hypoxia. We hypothesized that glutamate N-methyl-D-aspartate (NMDA) and non-NMDA receptors, nitric oxide (NO) synthase, and serotonin are involved in hypoxic ventilatory response (HVR) in Pikas. We tested the effects of NMDA (memantine) and non-NMDA receptors (DNQX) antagonists, NO synthase inhibitor (L-NAME), and selective serotonin reuptake inhibitors (fluoxetine) on ventilation and HVR in Pikas. Ventilatory parameters were measured before and after drug (or vehicle) injections in conscious Pikas at their natural living altitude (PIO2 86 mmHg) and after a hypoxic challenge (PIO2 57 mmHg, 3 min) to assess the influence of peripheral chemoreceptor on HVR. Minute ventilation (VI) and tidal volume (Vt) increased during hypoxic challenge after vehicle injection, whereas the Ti/Ttot ratio remained unchanged. The increase in VI and Vt observed with vehicle at PIO2-57, when compared with PIO2-86, was inhibited after memantine and fluoxetine injection, whereas the DNQX injection increased HVR. At PIO2-57, L-NAME induced an increase in the Ti/Ttot ratio when compared with vehicle. Therefore, the glutamate through NMDA-R/AMPA receptor bindings and serotonin pathway are implicated at the peripheral chemoreceptor level in HVR in Pikas. However, NO influences the ventilatory pattern of Pikas at their habitual living altitude.

Efficacy and tolerability of amifostine in elderly cancer patients

BACKGROUND

Amifostine is a cytoprotective agent used to prevent cisplatin nephrotoxicity. It is associated with dose-limiting acute toxicities of emetic symptoms (nausea and vomiting) and transient hypotension.

OBJECTIVE

The aim of this study was to analyze the efficacy and tolerability of amifostine in elderly cancer patients.

METHODS

This 18-month, prospective, comparative study was conducted at the Department of Internal Medicine, Adnan Menderes University Hospital (Aydin, Turkey). Adult (aged 40-<85 years) hospitalized patients with advanced-stage cancer without comorbid diseases were enrolled. Patients were divided into 2 groups: age <70 years (group 1) and ≥70 years (group 2). All patients were treated with amifostine + cisplatin-based chemotherapy (CT). Amifostine 910 mg/m(2) (maximum, 1500 mg) was administered as a 15-minute IV infusion. Clinical systolic and diastolic blood pressures (SBP and DBP, respectively) were measured at 0 minute (baseline), at 8 and 15 minutes of amifostine infusion, and at 30 minutes after the start of amifostine infusion. In addition to physical examination, chest radiography, electrocardiography, blood chemistry (including serum electrolytes and renal function tests), complete blood count, and complete urinalyses were performed before each CT administration and at the post-CT day of toxicity assessment.

RESULTS

Thirty-five consecutive patients were enrolled (22 men, 13 women; mean [SD] age, 61 [12] years; group 1, n = 22; group 2, n = 13). Patients received a total of 153 CT cycles (median, 4 cycles/patient; group 1, 96 cycles; group 2, 57 cycles). Amifostine caused significant SBP and DBP reductions at 8 minutes of infusion compared with baseline in groups 1 (both P < 0.001) and 2 (P = 0.002 and P = 0.006, respectively). Overall, 20 patients (57.1%) experienced ≥ 1 symptomatic hypotensive episode; these rates were not significantly different between groups 1 (11 cases, 50.0%) and 2 (9 cases, 69.2%). Amifostine infusion was interrupted a similar number of times (6 times in group 1 and 4 times in group 2 [6.3% and 7.0% of administrations, respectively]) due to hypotension, but could be restarted in all. At 15 minutes, mean SBP and DBP values were not significantly different from baseline in either group. The mean baseline SBP values were similar between groups at baseline, and, overall, the differences in mean SBP and DBP values were not significant between groups at any time point. All other toxicities were comparable, and serum creatinine concentrations did not change significantly from baseline with CT in either group.

CONCLUSIONS

In this study of the efficacy and tolerability of amifostine in elderly patients with advanced-stage cancer without comorbid diseases, amifostine was effective in reducing cisplatin-induced nephrotoxicity, with transient systolic and diastolic hypotension being the most prominent adverse effect. All other toxicities were either low grade or preventable. No significant differences in amifostine tolerability or toxicities were observed between the study groups.

Amifostine (Wr-2721) prevents indomethacin-induced gastric damage in rats: role of non-protein sulfhydryl groups and leukocyte adherence

This study was designed to evaluate the protective effect of amifostine on indomethacin-induced gastric damage, and the role of increased gastric non-protein sulfhydryl groups (NP-SH) and decreased leukocyte adherence in this event. Wistar rats were pretreated with amifostine (10, 30, or 90 mg/kg intraperitoneal (i.p.) or subcutaneous (s.c.)) or saline. After 30 min, the rats received indomethacin (20 mg/kg, by gavage) and were then killed 3 hr later. Macroscopic and microscopic gastric damage, concentration of gastric NP-SH, prostaglandin E2 (PGE2), and mesenteric leukocyte adherence (intravital microscopy) were assessed. Amifostine prevented significantly (P < 0.05), macroscopic or microscopic, indomethacin-induced gastric damage, and increased gastric NP-SH, in a dose-dependent manner, with a maximal effect at a dose of 90 mg/kg. Subcutaneous, but not i.p., amifostine administration decreased (P < 0.05) the indomethacin-induced increase in leukocyte adherence. Indomethacin-induced PGE2 depletion was not reversed by amifostine. Amifostine has a protective effect against indomethacin-induced gastropathy by increasing gastric NP-SH and decreasing leukocyte adherence.

Effects of Amifostine on Glycerol-Pretreated Rabbit Kidneys

Glycerol-induced acute renal failure is an experimental model for myoglobinuric nephropathy. Amifostine is a cytoprotective agent which scavenges the free radicals. Since there is enhanced production of reactive oxygen metabolites in glycerol-induced acute renal failure, we wanted to examine whether amifostine has a protective role against vascular reactivity and histological changes in kidneys isolated from glycerol-pretreated rabbits. Perfusion pressure was recorded from kidneys obtained from rabbits injected with glycerol 3 hr before the experiments and from glycerol-pretreated and non-pretreated rabbits injected with amifostine 30 min. before the experiments. Acetylcholine-induced (10(-8)-10(-5) M) vasodilatation was tested following the construction of submaximal vasoconstriction by phenylephrine. Histological investigation was performed using light microscope. Acetylcholine-induced vasodilatation was found to be significantly decreased in glycerol, glycerol+amifostine and amifostine groups compared to controls at all concentrations. Reduction in acetylcholine-induced vasodilation was more prominent in amifostine group compared to amifostine+glycerol group. There was histological renal damage in all experimental groups and this damage was more pronounced in glycerol+amifostine group. In conclusion, contrary to expectation, amifostine per se led to histological damage and potentiated the histological damage caused by glycerol and produced a decrease in acetylcholine-induced vasodilatation. The mechanisms by which amifostine exerts its effects are not known.

Oxidative study of patients with total body irradiation: effects of amifostine treatment

In patients undergoing bone marrow transplant (BMT), reactive oxygen species (ROS) are released as a consequence of the events related to the preparative regimen. Total body irradiation (TBI), which is known to generate ROS, is a routine preconditioning procedure prior to BMT. Several studies have demonstrated that amifostine protects normal tissues. In the present report, we investigated the oxidative state of plasma and erythrocytes in 21 patients with hematological malignancies undergoing TBI. The dose fraction was 160 cGy, twice daily (eight sessions). For ROS detection, we used electron spin resonance spectroscopy and spin-trapping technique. In all, 15 patients received amifostine prior to the irradiation and six did not. No free radical signal was detected in the plasma samples spectrum of 15 amifostine-treated patients, and five of six samples of nontreated patients showed ROS signal. Only two of 15 treated patients had mucositis degree higher than 2, whereas five of six nontreated patients suffered this complication. The average hospitalization days in treated and nontreated patients were 23.5 and 29.7, respectively. This work represents an original observation; we found by direct measurements of free radicals that ROS are released during TBI, and confirmed the amifostine radical scavenger activity.

The genetic pathogenesis of colorectal cancer

Research over the past decade has established that the progression from normal colonic epithelium to colon cancer is in every case a step-wise process in which specific pathologic and molecular markers can be identified for study and clinical therapy. Genetic and epigenetic instability appears fundamentally important to this process. We have now determined that this neoplastic progression occurs along a limited set of pathways, in which specific tumor suppressors are inactivated or oncogenes activated in a defined order. Although incomplete, our new understanding of the process of carcinogenesis in the colon has already significantly impacted patient care and will continue to do so for the foreseeable future. Increasingly rapid research developments and technologic advances will transform the way we prevent, diagnose, and treat this common and deadly form of cancer.

Amifostine in clinical oncology: current use and future applications

Amifostine (Ethyol), an inorganic thiophosphate, is a selective broad-spectrum cytoprotector of normal tissues that provides cytoprotection against ionizing radiation and chemotherapeutic agents, thus preserving the efficacy of radiotherapy and chemotherapy. This review summarizes the preclinical data and clinical experience with amifostine, and provides insight into future clinical directions. Amifostine, an inactive pro-drug, is transformed to an active thiol after dephosphorylation by alkaline phosphatase found in the normal endothelium. The absence of alkaline phosphatase in the tumoral endothelium and stromal components, and the hypovascularity and acidity of the tumor environment, may explain its cytoprotective selectivity. The cytoprotective mechanism of amifostine is complicated, involving free radical scavenging, DNA protection and repair acceleration, and induction of cellular hypoxia. Intravenous administration of amifostine 740-900 mg/m(2) before chemotherapy and 250-350 mg/m(2) before each radiotherapy fraction are widely used regimens. The US Food and Drug Administration has approved the use of amifostine as a cytoprotector for cisplatin chemotherapy and for radiation-induced xerostomia. Ongoing trials are being conducted to determine the efficacy of amifostine in reducing radiation-induced mucositis and other toxicities. Novel schedules and routes of administration are under investigation, and may further simplify the use of amifostine and considerably broaden its applications.

Radioprotective and locomotor responses of mice treated with nimodipine alone and in combination with WR-151327

The effect of combining a radiation-protective phosphorothioate with another agent was investigated in an attempt to increase radioprotection and reduce toxicity. The calcium channel blocker nimodipine (NIMO) was administered alone (1 or 10 mg kg-1) or in combination with 200 mg kg-1 of the phosphorothioate radioprotector WR-151327 (WR) (S-3-(3-methylaminopropylamino)propylphosphorothioic acid). Radioprotection as measured (30-day survival) of mice treated i.p. 30 min before (60)Co irradiation at a dose rate of 1 Gy min-1 was evaluated in CD2F1 male mice. The effects of nimodipine and WR-151327 on locomotor activity were investigated also in a separate group of non-irradiated mice. The LD(50/30) for the Emulphor vehicle control group was 8.56. For nimodipine alone (1 or 10 mg kg-1) the LD(50/30)was 8.39 and 10.21 Gy, respectively, yielding dose modification factors (DMFs) of 0.98 and 1.19, respectively. When WR-151327 was given alone, the <LD(50/30) was 12.48 Gy (DMF = 1.46; P < 0.05 from vehicle). WR-151327 combined with 1 or 10 mg kg-1 nimodipine resulted in an LD(50/30) of 12.73 Gy (DMF 1.49, P < 0.05 from vehicle), and when WR-151327 was combined with 10 mg kg-1 nimodipine the LD(50/30) was 14.29 Gy (DMF = 1.67, P < 0.001 from WR-151327). For either dose of nimodipine, locomotor activity did not differ from vehicle. WR-151327 and WR-151327 + 1 mg kg-1 nimodipine resulted in locomotor decrements for up to 4 h post-administration (P < 0.05 from vehicle), and WR-151327 + 10 mg kg-1 nimodipine for up to 6 h (P < 0.05 from WR-151327). Therefore, although there was an additive radioprotective effect when the higher dose of nimodipine was combined with WR-151327, the locomotor decrement was also enhanced. These results demonstrate that a combination of nimodipine and a phosphorothioate such as WR-151327 may be useful as a clinical setting where behavioral and physiological side-effects can be monitored. Published in 2001 by John Wiley & Sons, Ltd.

The potential role of amifostine in the treatment of non small cell lung cancer

Amifostine protects healthy tissues but not tumor cells from the damage induced by cytotoxic treatments, particularly ionizing radiations, alkylating and platinating agents. The clinical effectiveness of amifostine has been demonstrated by randomized trials in ovarian and head-and-neck cancer patients treated with chemotherapy with or without radiation therapy. The available pharmacoeconomic data confirm a favorable cost/utility ratio. The majority of non small cell lung cancer (NSCLC) patients receive radio and/or chemotherapy. A role for amifostine in these patients has been hypothesized, and some experiences performed. The aim of this paper is to outline the present role of amifostine in the treatment of NSCLC.

Pharmacokinetics of amifostine and its metabolites in patients

The pharmacokinetics of the cytoprotective agent amifostine (EthyolR; WR 2721) and its main metabolites (WR 1065 and the disulphides) were studied in patients participating in two phase I trials concerning carboplatin or cisplatin in combination with amifostine. Patients were treated with a single dose or three doses of amifostine (740 or 910 mg/m2). The single or first dose was given as a 15 min i.v. infusion just before administration of the chemotherapeutic agent. The additional two infusions were administered 2 and 4 h thereafter. Amifostine was rapidly cleared from the plasma, due to, at least in part, the fast conversion into WR 1065. A biphasic decrease with a final half-life of 0.8 h was observed. The active metabolite WR 1065 was cleared from the plasma with a final half-life of 7.3 +/- 3.6 h. The short initial half-life of WR 1065 can be explained by its fast uptake in tissues and the formation of disulphides. The disulphides were cleared with a final half-life of 8.4-13.4 h and were detectable for at least 24 h after treatment. They may serve as an exchangeable pool of WR 1065. The amifostine peak values at the end of each 15 min infusion did not accumulate in the multiple dosing schedule. For WR 1065 a trend towards an increase in the peak levels was observed [C1,max: 47.5 +/- 11.9 microM, C2,max: 79.0 +/- 13.2 microM, C3,max: 84.8 +/- 15.1 microM, (n = 6)], whereas a trend towards a small decrease was observed for the peak levels of the disulphides [C1,max: 184.2 +/- 12.6 microM, C2,max: 175.0 +/- 23.7 microM, C3,max: 166.0 +/- 17.2 microM, (n = 6)]. This latter finding might suggest a saturation of the disulphide formation or a change in the uptake or elimination of WR 1065, which would result in higher WR 1065 levels in plasma and tissues, after multiple doses of amifostine.