Biomedical subjects
Publications and source records attributed to M J Lind.
We report three patients who had serious disturbance of anticoagulant control while receiving ifosfamide/mesna-containing cytotoxic chemotherapy in association with warfarin. In view of the likely biological potentiation of warfarin by ifosfamide/mesna, close monitoring of anticoagulant control should be performed during the co-administration of these drugs.
The effect of ifosfamide and its metabolites on intracellular levels of glutathione in P388 cells in vitro has been studied. It is demonstrated that glutathione depletion occurs only in the presence of 4-hydroperoxyifosfamide and chloroacetaldehyde. In contrast isophosphoramide mustard had no effect on glutathione levels in intact cells. The concentration of 4-hydroperoxyifosfamide required to reduce glutathione levels by 50% was approximately 1 mM and this represents a concentration far in excess of that achievable in patients receiving the drug. However the concentration of chloroacetaldehyde (approximately 100 microM) required to reduce intracellular levels of glutathione to a similar extent is attained in patients receiving ifosfamide. The glutathione levels in lymphocytes isolated from a patient undergoing an eight hour infusion of ifosfamide showed a marked decrease to about 30% of their original value. We conclude that ifosfamide causes glutathione depletion in vivo and the majority of this can be accounted for by the production of chloroacetaldehyde.
20 patients with advanced non-small cell lung cancer were treated with ifosfamide and mesna 1.5 g/m2 daily for 5 days; 10 received the drug by mouth and 10 i.v. Both schedules resulted in a reduction in the elimination half-life with an increased total and nonrenal clearance of ifosfamide over the 5-day period. Oral administration resulted in an unacceptably high incidence of encephalopathy(5/10) which was not seen in the i.v. group. In two patients this encephalopathy manifested itself as coma which lasted for 24 to 48 h but was fully reversible and in the other three cases as somnolence occurring for more than 50% of the patients' waking hours. Nadir blood counts and response rates were similar in both arms. The encephalopathy suggests that there are metabolic differences between the i.v. and oral routes and that a metabolite rather than the parent drug is responsible for this syndrome. In addition it was shown that the total and nonrenal clearance of the drug was significantly less when the drug was administered orally. None of the pharmacokinetic parameters either singly or in combination predicted for ifosfamide toxicity. No correlation between the creatinine clearance and ifosfamide renal clearance was demonstrated suggesting tubular reabsorption of the drug. In conclusion, ifosfamide cannot be given orally at the conventionally employed i.v. doses.
The pharmacokinetics of intravenous ifosfamide were determined in 16 patients with carcinoma of the bronchus. In all 25% (4) of these patients were obese (i.e. greater than 20% over their ideal body weight). The terminal elimination half-life (t1/2 beta) was found to be higher in the obese group than in the control group (6.36 h, range 5.77-7.45 h) vs 4.95 h, range 1.82-6.48 h) (P less than 0.05). This prolongation of the elimination half-life was due to an increased volume of distribution (Vd beta) in the obese group (42.81 1, range 35.49-51.90 l) vs 33.70 l range (17.76-50.62 l) (P less than 0.05). There was therefore no significant difference in total plasma clearance between the obese and normal groups. No correlation of ifosfamide plasma half-life was observed with total body weight (TBW) or ideal body weight (IBW). However, a significant positive correlation was observed between the percentage of IBW and plasma half-life. A strong positive correlation was observed between IBW and the plasma clearance of ifosfamide. The Vd beta correlated with both TBW and the percentage of IBW, but not with IBW itself. When Vd beta was normalised for IBW, there was a strong positive correlation with the percentage of IBW, suggesting that ifosfamide distribution into the TBW is higher than that into the IBW.
Forty-six patients with early (Stage I and II) ovarian cancer referred as free of residual disease after primary surgery, selected for high-risk features, were treated with adjuvant single-agent alkylating therapy comprising either intravenous cyclophosphamide (1 g/m2) in 36 patients, or oral melphalan (0.2 mg/kg daily for 5 days) in eight. Cyclophosphamide was repeated every 3 weeks for 10 cycles and melphalan every 6 weeks for 12 cycles. With a median follow-up of 36+ months, 18 patients have relapsed. The actuarial 5-year relapse-free survival was 48% and the overall 5-year survival was 54%; median survival was 84 months. Pretreatment FIGO stage was the single most important predictor of relapse-free and overall survival duration. For patients with Stage IA and IB tumours the 5-year actuarial relapse-free survival was 89%; for patients with stage IC and II (all substages), the 5-year relapse-free survival was 24% (P = 0.001). For this latter group adjuvant single alkylating agent therapy was not adequate and alternative therapeutic regimens are required. The problem of suboptimal primary surgical staging is also addressed.
Forty-five patients with advanced non-small cell lung cancer (NSCLC), with progressive inoperable tumors were treated. Twenty-three patients were of "limited" stage. Six patients had received previous thoracic radiotherapy. Patients with central nervous system (CNS) metastases, Karnofsky scores of less than 30 or more than 70, and patients over 70 years of age were excluded from the study. Cyclophosphamide (2.5 g/m2) was infused intravenously over 3 hours with the same Mesna dose. At the midpoint of the infusion, 3.5 g/m2 infosfamide was delivered as a bolus. Additional Mesna was administered over the next 8 hours. A maximum of four courses were given at three weekly intervals. One-hundred-thirty-eight courses were administered and 53% of patients completed all four treatments. The response rate was 38%, with three (7%) complete responses. Seven additional patients (15%) with stable disease symptomatically improved by two steps or more on the Karnofsky scale at the end of treatment. Median survival for all 45 patients was 7 months, range less than 1 to 25 months. Sixteen courses were complicated by Grade 3 thrombocytopaenia and/or leukopenia (Grade 4 on six occasions, Grade 3 on seven occasions) on the blood count taken immediately before chemotherapy. Intravenous antibiotics were required on 14% of the total number of courses; and three patients died of probable treatment related causes. Two episodes of severe ifosfamide encephalopathy occurred but recovery was complete, and four episodes of frank hematuria also occurred. The Karnofsky score was more than 70 in 33% of patients one month after the end of chemotherapy compared with 0% before treatment. Unlike many chemotherapeutic regimens for NSCLC, double alkylating agent treatment with ifosfamide and cyclophosphamide improved the performance status without major toxicity in a selected patient population. The overall survival, however, remains short and further alkylating agent combinations need to be considered in the future.
Sixty patients with FIGO stage IIb, IIc, III and IV ovarian cancer were entered into a randomized Phase III study of cyclophosphamide 600 mg/m2 with cisplatin 100 mg/m2, iproplatin 240 mg/m2 or carboplatin 300 mg/m2. Dose modifications were made according to renal function and myelotoxicity. The arms containing carboplatin (CBDCA) and iproplatin (CHIP) were not shown to be significantly different from the cisplatin containing arm with regard to response rate, duration of response and survival. Subjective toxicity showed that cisplatin and cyclophosphamide therapy was associated with more nausea and vomiting (P = 0.0005). The duration of vomiting showed a significant increase with successive courses of chemotherapy for the cisplatin containing arm only (P less than 0.003). The cyclophosphamide/CHIP combination caused significantly more diarrhoea (P less than 0.0006). Alopecia was more severe (P less than 0.02), and neurotoxicity was more common, in patients who received cyclophosphamide and cisplatin (paraesthesiae P = 0.0007, tinnitus P less than 0.00005, deafness P = 0.0018). All three combinations caused cumulative toxicity on haemoglobin (Hb) (P less than 0.001 for each treatment), leukocyte count (WCC) (P less than 0.0005 for each treatment), and platelet count (P less than 0.0005 for each treatment). The degree of fall in Hb for each course of therapy was greater in the cisplatin containing arm compared with the CHIP and CBDCA arms which were not significantly different from each other (P = 0.0005). For WCC the cisplatin/cyclophosphamide regimen was significantly less toxic than CHIP/cyclophosphamide, with CBDCA/cyclophosphamide falling between the two and not being significantly different from either (P = 0.0005). The CHIP containing arm caused more thrombocytopenia than the other arms which were of equal toxicity (P less than 0.0005). Serum creatinine showed a gradual significant overall rise with each course of cisplatin/cyclophosphamide therapy (P less than 0.0005), whereas the CBDCA arm showed no change and the CHIP arm showed a small fall in serum creatinine after most courses of therapy. This study showed that CHIP or CBDCA in combination with cyclophosphamide was less toxic than cisplatin/cyclophosphamide therapy with regard to alopecia, degree and duration of nausea and vomiting, renal toxicity, neurotoxicity and anaemia. The CHIP/cyclophosphamide regimen caused more thrombocytopenia and diarrhoea. The CHIP and CBDCA containing arms caused more leukopenia than the cisplatin containing regimen. Either iproplatin or carboplatin would be an acceptable alternative to cisplatin in chemotherapy regimens, and would result in reduced toxicity.
Methylene dimethane sulphonate (MDMS), the first member of the homologous series of dimethane sulphonic acid esters, was administered to 19 patients with advanced epithelial ovarian cancer. All patients had received prior chemotherapy and in addition 3 had received prior radiotherapy. MDMS was given as an i.v. bolus injection at a dose of 125mg m-2 and repeated in a q35 day schedule. Ten patients received only one course, six two courses, two three courses and one four courses. The major toxicity was thrombocytopenia which was cumulative. Serious neutropenia did not occur and no infective episodes requiring i.v. antibiotics were seen. Seven patients experience hair loss and four nausea and vomiting. Sixteen patients were evaluable for response but no objective remissions were seen although three patients had stable disease lasting at least 8 weeks. MDMS is therefore not recommended for further trial in epithelial ovarian carcinoma.
Plasma and salivary caffeine concentrations were measured by gas-liquid chromatography in 6 healthy caffeine-free volunteers following oral administration of 50, 300, 500 and 750 mg caffeine. Caffeine was also given to a single subject intravenously in doses of 300, 500 and 750 mg. Caffeine was rapidly absorbed and was completely available at all doses. The apparent first-order elimination rate constant decreased linearly with dose and was 0.163 +/- 0.081 h-1 for 50 mg and 0.098 +/- 0.027 h-1 for 750 mg. The total body clearance was unaffected by dose and was 0.98 +/- 0.38 ml/min/kg. There was a trend towards increasing apparent volume of distribution with increasing dose. A linear relationship existed between the area under the plasma concentration, time curve and dose and dose-normalised plasma concentration, time plots were superimposable. These findings suggest that caffeine obeys linear pharmacokinetics over the dose range investigated. Despite significant inter-individual differences in pharmacokinetic parameters there was good reproducibility within 5 subjects given 300 mg caffeine orally on 3 occasions. Salivary caffeine levels probably reflect the unbound plasma caffeine concentration and can be used to estimate the pharmacokinetic parameters of the drug. Overall the saliva/plasma concentration ratio was 0.74 +/- 0.08 but within subjects some time-dependence of the ratio was found with higher ratios initially (even after intravenous administration) and lower ratios at longer time intervals after the dose. Urinary elimination of caffeine was low and independent of dose: 1.83% of the dose was eliminated unchanged.
Neurological complications associated with cyclosporin administration are well documented. However their histopathological basis are ill-understood. We describe below a case of demyelination following cyclosporin administration to a patient following allogeneic bone marrow transplantation.