A pharmacokinetic study of high-dose metoclopramide suppositories.

The pharmacokinetics of high-dose rectal metoclopramide have been studied in nine patients after administration of 150-mg suppositories. The results have been compared to the pharmacokinetics of the drug in five patients who received the same dose of metoclopramide intravenously. Administration of a metoclopramide suppository achieved plasma drug concentrations that are associated with the effective treatment of cytotoxic drug-induced nausea and vomiting. In three patients who received the drug by both routes the systemic availability of the suppository appeared to be complete. High-dose metoclopramide suppositories are convenient and may be advantageous in the treatment of medical oncology out-patients.

Pharmacokinetics of tauromustine in cancer patients. Phase I studies.

The pharmacokinetic properties of tauromustine (TCNU) were studied in 31 cancer patients who participated in phase I trials. The patients received single oral doses of tauromustine in the range of 20-170 mg/m2. Plasma samples were taken over 24 h after administration and analysed for tauromustine by reversed-phase liquid chromatography. Parent TCNU could be demonstrated in the plasma of all patients. Its absorption was rapid (tmax = 38 +/- 22 min), the half-life was 57 +/- 22 min (mean +/- SD), and maximal concentration (Cmax) and AUC values were linearly related to the dose level. Thus, our study does not indicate dose-dependent pharmacokinetics for the drug in the range of 20-170 mg/m2. Thrombocytopenia was the dose-limiting toxicity of TCNU; the reduction of platelet counts appeared to be linearly related to the log dose and Cmax and AUC values. TCNU appears to exhibit pharmacokinetic properties that are different from those of other nitrosoureas, which might be important for the clinical effect of the drug.

Phase I study of TCNU, a novel nitrosourea.

TCNU is a chloroethyl nitrosourea based on the endogenous amino acid taurine. This paper reports its first evaluation in man. Eighty-four patients with refractory cancer received 12 dose escalations from 10-150 mg/m2 TCNU administered orally every 6 weeks. Clinical side-effects were predominantly gastro-intestinal but dose-limiting toxicity was thrombocytopenia. Pharmacokinetic monitoring with an HPLC assay sensitive to the nanogram range demonstrated unchanged TCNU in plasma for up to 8 h following administration. The mean half-life was 60 min. Clinical responses were seen in melanoma (four patients), lung cancer (two squamous, one small cell) and one patient each with renal and stomach cancer. These responses, together with the unusual pharmacokinetic profile of TCNU, warrant exploration in disease-orientated phase II studies at a recommended dose of 130 mg/m2 p.o. q 5 weeks.

Optimising antiemesis in cancer chemotherapy: efficacy of continuous versus intermittent infusion of high dose metoclopramide in emesis induced by cisplatin.

Thirty three untreated patients being given cisplatin received metoclopramide (7 mg/kg) for antiemesis by either continuous or intermittent infusion in a random order. Each patient received intravenous dexamethasone in addition. High pressure liquid chromatography was used to measure plasma concentrations of metoclopramide. The two regimens were evaluated for antiemetic efficacy and the incidence of side effects. The intermittent metoclopramide regimen resulted in peak and trough plasma concentrations of metoclopramide with accumulation at eight hours, while the loading dose and continuous infusion resulted in mean plasma concentrations greater than 0.85 micrograms/ml (2.8 mumol/l) throughout the eight hour period. The continuous infusion was associated with a significant improvement in nausea and vomiting and reduction in diarrhoea. Major control of emesis (two episodes or fewer) was achieved in 27 patients receiving continuous metoclopramide compared with 18 receiving intermittent metoclopramide.

The clinical pharmacology of mitozantrone.

The pharmacological disposition of the anthracenedione mitozantrone has been measured in 11 patients with six different tumour types. Administered at 14 mg/m2 as a 30-min infusion, the drug was assayed by a high-pressure liquid chromatographic technique sensitive to 1 ng mitozantrone/ml plasma. The mean half-lives for mitozantrone in plasma were as follows: alpha, 9.4 min; beta, 1.6 h; gamma, 23 h. The mean volume of distribution (Vd) was 1565 l. For two patients with impaired liver function the T1/2 gamma and Vd were 63.1 h and 4853 l, respectively. Less than 5% of the administered drug was excreted in urine, but two urinary metabolites were identified. These were not influenced by pre incubation of urine samples with beta-glucuronidase or sulphatase, suggesting that neither metabolite is a glucuronide or a sulphate conjugate of mitozantrone. Hepatic metabolism is the major route of elimination of mitozantrone, and caution should be exercised when using this drug for patients with hepatic dysfunction.

Emesis due to cancer chemotherapy: results of a prospective, randomised, double-blind trial of varying doses of metoclopramide in the management of cis-platinum-induced vomiting.

A randomised, double-blind prospective trial was conducted to determine the relative anti-emetic efficacy of three dose levels of metoclopramide in cancer patients receiving combination chemotherapy including cis-platinum. With consecutive courses of chemotherapy, 60 patients received doses of either 3,5 or 10 mg/kg metoclopramide (50, 54 or 55 courses respectively) in a randomly assigned sequence. Major control of emesis (less than or equal to 2 vomits) was achieved in 38% of 159 patient treatments. There were no significant differences in either anti-emetic efficacy or the incidence of side-effects between the three doses used. It is concluded that while metoclopramide is an effective anti-emetic for patients receiving cisplatinum therapy, no advantage accrues to the use of doses in excess of 3 mg/kg (total dose).