Pharmacokinetics and toxicity of two schedules of high dose epirubicin.

Epirubicin, a stereoisomer of doxorubicin, is reported to have equal antitumor activity with lower cardiac and systemic toxicity. Recently the maximum tolerated dose of this drug has been revised upwards with reported increased response rates. However, the pharmacokinetics of epirubicin at high doses have never been reported. Accordingly, this study was designed to evaluate the pharmacokinetics of epirubicin when administered as either a 15-min i.v. bolus or a 6-h i.v. infusion in a phase I study at high doses. Nineteen patients with a variety of malignancies were given a total of 52 cycles of epirubicin at doses of 90 to 150 mg/m2 given once every 3 weeks. The maximum tolerated dose was 150 mg/m2 epirubicin given either as a bolus or as an infusion. The major dose-limiting toxicity was neutropenia. Interpatient variation occurred in the pharmacokinetics at each dose level but overall there were dose-dependent pharmacokinetics. This was manifested as a disproportionate increase in plasma levels and areas under the curve as the epirubicin dose was increased from 90 to 150 mg/m2. The pharmacokinetics of epirubicin could best be described by an open two-compartment model. Peak plasma concentrations were attained at a median of 12 min following the bolus injection and concentrations approached the steady state within a median of 55 min following the start of the 6-h infusion. Administration of the 150 mg/m2 dose over the 6 h compared to the bolus administration was associated with a 92% decrease in peak concentration from 3088 +/- 1503 to 234 +/- 126 ng/ml. This was not associated with an appreciable change in hematological or nonhematological toxicities. The median distribution half-life was 10 min and the median elimination half-life was 42.0 h. The cumulative renal excretion of the parent compound accounted for less than 2% of the administered dose. The major metabolites in both plasma and urine samples were 4'-O-beta-D-glucuronyl-4'-epidoxorubicin, 13-S-dihydro-4'-epidoxorubicin, and 4'-O-beta-D-glucuronyl-13-S-dihydro-4'-epidoxorubicin. This study demonstrates that a 135 mg/m2 bolus infusion given on a 3-weekly schedule is an appropriate initial dose for further clinical studies.

Hereditary protein C deficiency associated with mutations in exon IX of the protein C gene.

This report describes five families with symptomatic hereditary protein C deficiency. Using a polymerase chain reaction (PCR)-based method, the entire coding sequence and intron-exon boundaries of the protein C gene was amplified from genomic DNA. In each family a single point mutation in the protein C gene was identified. Two unrelated families were found to share the same mutation, while the other three had different mutations. In the first two families with type I protein C deficiency the normal cytosine residue at nucleotide position 8551 in the protein C gene was replaced by thymidine leading to substitution of the normal proline residue at amino acid position 279 by leucine. In the third family with type I deficiency a previously undescribed mutation was identified. In this family the guanosine residue at position 8559 was replaced by adenosine (glycine 282 substituted by serine). In the fourth family, also with type I deficiency, guanosine 8589 was replaced by adenosine (glycine 292 substituted by serine). The fifth family had type II deficiency and in affected members cytosine 8769 was replaced by thymidine (arginine 352 substituted by tryptophan). All these mutations lead to amino acid substitutions in the serine protease domain of the mature protein. All were able to be confirmed by restriction enzyme analysis of PCR-derived DNA. In addition the novel mutation at nucleotide position 8559 was also demonstrable using single strand conformation polymorphism (SSCP) analysis of PCR-derived DNA. These mutations were likely examples of deamination of methylated cytosine occurring in cytosine-phosphate-guanosine (CpG) dinucleotide sequences. These findings confirm the genetic heterogeneity of hereditary protein C deficiency in these families.

An evaluation of 200 consecutive patients with spontaneous or recurrent thrombosis for primary hypercoagulable states.

Two hundred consecutive patients who were referred for evaluation of spontaneous or recurrent thrombosis were investigated for possible hypercoagulable states to determine the relative frequencies of these conditions in the Australian population and to identify features that would indicate which patients should be investigated with the expensive battery of tests for hypercoagulable states. Thirty-two percent were found to have prolongation of the postvenous occlusion euglobulin clot lysis time (PVO-ELT), 32% were found to have elevated levels of plasminogen activator inhibitor-1 (PAI) and 66% were found to have reduced release of tissue plasminogen activator (tPA). Antiphospholipid antibodies were found in 12%. Hereditary antithrombin III deficiency was found in 2%. Hereditary deficiency of the naturally-occurring anti-coagulant factors protein C and protein S was found in 2%. Age, sex, site of thrombosis (venous or arterial), or presence of a family history was not helpful in predicting a group more likely to have abnormal investigation results. Reduced fibrinolytic activity and the presence of antiphospholipid antibodies are the most common findings in patients with thromboembolic disease. Further prospective studies are required to assess the natural history and appropriate management of patients with these abnormalities.

Symptomatic choroidal metastases in breast cancer.

A series of 21 consecutive patients with carcinoma of the breast and symptomatic choroidal metastases was reviewed. All patients were symptomatic of choroidal metastases at presentation. Most patients had disease progression at other sites at the time of diagnosis. The incidence of cerebral metastases was not increased in this group compared to that in patients with metastatic breast cancer at other sites. Radiotherapy using a direct anterior field proved effective palliation for this disease site. Of the 32 eyes treated, serial visual acuity was documented in 23. Seventeen showed objective improvement and six showed stabilisation. The median duration of improvement was 11.5 months.