Metabolism and disposition of the anticancer quinolone derivative vosaroxin, a novel inhibitor of topoisomerase II.

Background Vosaroxin is a first-in-class anticancer quinolone derivative that is being investigated for patients with relapsed or refractory acute myeloid leukemia (AML). The primary objective of this study was to quantitatively determine the pharmacokinetics of vosaroxin and its metabolites in patients with advanced solid tumors. Methods This mass balance study investigated the pharmacokinetics (distribution, metabolism, and excretion) of vosaroxin in cancer patients after a single dose of 60 mg/m2 14C-vosaroxin, administered as short intravenous injection. Blood, urine and feces were collected over 168 h after injection or until recovered radioactivity over 24 h was less than 1% of the administered dose (whichever was earlier). Total radioactivity (TRA), vosaroxin and metabolites were studied in all matrices. Results Unchanged vosaroxin was the major species identified in plasma, urine, and feces. N-desmethylvosaroxin was the only circulating metabolite detected in plasma, accounting for <3% of the administered dose. However, in plasma, the combined vosaroxin + N-desmethylvosaroxin AUC0-∞ was 21% lower than the TRA AUC0-∞ , suggesting the possible formation of protein bound metabolites after 48 h when the concentration-time profiles diverged. The mean recovery of TRA in excreta was 81.3% of the total administered dose; 53.1% was excreted through feces and 28.2% through urine. Conclusions Unchanged vosaroxin was the major compound found in the excreta, although 10 minor metabolites were detected. The biotransformation reactions were demethylation, hydrogenation, decarboxylation and phase II conjugation including glucuronidation.

A phase I, dose escalation, pharmacodynamic, pharmacokinetic, and food-effect study of α2 integrin inhibitor E7820 in patients with advanced solid tumors.

UNLABELLED: Introduction E7820 is an orally administered sulfonamide that inhibits alfa-2-integrin mRNA expression. Pre-clinically E7820 showed tumor anti-angiogenic effects in various tumor cell lines and xenograft mouse models. Human daily dosing of 100 mg QD had previously been shown to be safe and tolerable. Methods The study consisted of two parts: Part A (food effect) and Part B (determination of maximum tolerated dose (MTD) for bi-daily (BID) dosing). E7820 dosing started at 50 mg BID with planned escalation to 60, 80 and 100 mg BID every 28 days. Results Fifteen patients were enrolled in Part A and 26 in Part B. The most frequent adverse events of all grades were constipation, diarrhea, nausea, and fatigue while anemia, neutropenia, and fatigue were most frequent grade ≥3 toxicities. At dose-level 60 mg BID, two patients experienced dose-limiting toxicities (grade 3 neutropenic sepsis and grade 4 neutropenia). Therefore the recommended dose (RD) was 50 mg BID. Food had no effect on E7820 exposure. E7820 exposure following twice daily administration was dose-proportional. Expression of platelet integrin-α2 measured as a response biomarker in Part B, generally decreased by a median 7.7 % from baseline following treatment with 50 mg BID E7820. Reduction was most pronounced within 1-week post treatment. The median duration of treatment was median 54, range 20-111 days. The best overall response in any treatment group was stable disease (SD): 23.1 % in Part A (100 mg QD); at the RD 66.7 % (12 of 18 patients) and 40 % in the 60 mg BID group in Part B. CONCLUSIONS: Food had no effect on E7820 exposure. A dose of 50 mg BID was considered the MTD. Treatment with E7820 is safe and tolerable with 2/3 of patients (66.7 %) at MTD having SD as their best response.

Phase I and pharmacological study of pazopanib in combination with oral topotecan in patients with advanced solid tumours.

BACKGROUND: This phase I study evaluated the safety, tolerability, maximum tolerated dose (MTD) and pharmacokinetics of two dosing schedules of oral topotecan in combination with pazopanib in patients with advanced solid tumours. METHODS: Stage I of this study was to determine whether there was an impact of pazopanib on topotecan exposure. In stage II, the MTD and safety profile of oral topotecan given weekly on days 1, 8 and 15 in a 28-day cycle; or daily-times-five on days 1-5 in a 21-day cycle, both in combination with daily pazopanib, were explored. RESULTS: In total, 67 patients were enroled. Pazopanib co-administration caused a substantial increase in exposure to total topotecan (1.7-fold) compared with topotecan alone, which is considered clinically relevant. Topotecan had no effect on pazopanib concentrations. Safety findings were consistent with the known profile of both agents. There were three drug-related deaths, liver failure, tumour haemorrhage and myelosuppression. Two patients experienced dose-limiting toxicities (DLTs; hand-foot syndrome, myelosuppression and diarrhoea) on the weekly topotecan schedule and four patients experienced DLTs (myelosuppression) on the daily-times-five topotecan schedule. When combined with pazopanib, 800 mg daily, the recommended doses for oral topotecan are: 8 mg weekly and 2.5 mg daily-times-five. Seven of eight patients with partial response had platinum-resistant ovarian cancer. In addition, 54% of patients had stable disease with 22% stable for 6 months. CONCLUSIONS: Total topotecan exposure is 1.7-fold higher when co-administered with pazopanib. Both schedules of administration were tolerated and would permit further evaluation, especially the weekly schedule.

Eribulin mesylate pharmacokinetics in patients with solid tumors receiving repeated oral ketoconazole.

Purpose To study the influence of repeated oral administration of ketoconazole, a potent CYP3A4 inhibitor, on the plasma pharmacokinetics of eribulin mesylate administered by single-dose intravenous infusion. Eribulin mesylate is a non-taxane microtubule dynamics inhibitor that is currently under development in phase I-III trials for the treatment of solid tumors. Experimental design A randomized, open-label, two treatments, two sequences, crossover phase I study was performed in patients with advanced solid tumors. Treatments were given on day 1 and day 15 and consisted of 1.4 mg/m(2) eribulin mesylate alone or 0.7 mg/m(2) eribulin mesylate plus 200 mg ketoconazole on the day of eribulin mesylate administration and the following day. Pharmacokinetic sampling for determination of eribulin plasma concentration was performed up to 144 h following administration of eribulin mesylate. Also safety and anti-tumor activity were determined. Results Pharmacokinetic sampling and analysis was completed in ten patients. Statistical analysis of dose-normalized log-transformed AUC0-∞ and Cmax indicated that single-dose exposure of eribulin was not statistically different when co-administered with ketoconazole (ratio of geometric least square means: 0.95 (90%CI: 0.80-1.12) and 0.97 (90%CI: 0.83-1.12), respectively) in patients with solid tumors. Ketoconazole had no effect on eribulin clearance and elimination half-life. The most frequently reported treatment related adverse events were fatigue and nausea, each reported in 8/12 patients. Seven patients (58.3 %) achieved stable disease as best overall response. Conclusions The results indicate that eribulin mesylate can be safely co-administered with ketoconazole. Drug-drug interactions are not expected with other CYP3A4 inhibitors.

Pharmacokinetics of eribulin mesylate in patients with solid tumors and hepatic impairment.

PURPOSE: The aim of this study was to determine the plasma pharmacokinetics of eribulin mesylate in patients with solid tumors with mild and moderate hepatic impairment. PATIENTS AND METHODS: A phase I, pharmacokinetic study was performed in patients with advanced solid tumors and normal hepatic function or Child-Pugh A (mild) or Child-Pugh B (moderate) hepatic impairment. Treatments were given on day 1 and 8 of a 21-day cycle and consisted of 1.4, 1.1 and 0.7 mg/m(2) eribulin mesylate, for normal hepatic function, Child-Pugh A and B hepatic impairment, respectively. Also safety and anti-tumor activity were determined. RESULTS: Hepatic impairment increased exposure to eribulin. In patients with Child-Pugh A (N = 7) and Child-Pugh B (N = 5), mean dose-normalized AUC(0-∞) was 1.75-fold (90 % confidence intervals (CI): 1.16-2.65) and 2.48-fold (90 % CI: 1.57-3.92) increased, respectively, compared with patients who have normal function (N = 6). The most frequently reported treatment-related events were alopecia (12/18) and fatigue (7/18) and these were observed across all groups. Nine patients (50 %) had stable disease as best response. CONCLUSIONS: A reduced dose of 1.1 and 0.7 mg/m(2) of eribulin mesylate is recommended for patients with Child-Pugh A or B hepatic impairment, respectively.

Phase I evaluation of telatinib, a VEGF receptor tyrosine kinase inhibitor, in combination with bevacizumab in subjects with advanced solid tumors.

BACKGROUND: Blocking both receptor and ligand of the vascular endothelial growth factor (receptor) VEGF(R) pathway might be feasible and increase antitumor activity. This phase I study investigated telatinib, an oral tyrosine kinase inhibitor targeting VEGFR-2, combined with bevacizumab, in adults with solid tumors. PATIENTS AND METHODS: Twenty-six patients were treated in successive cohorts with telatinib (twice-daily continuously, 450-900 mg) or bevacizumab (bi-weekly, starting dose 5 mg/kg). Safety, pharmacokinetics, endothelial (progenitor) cell (E(P)C)/growth factor kinetics and efficacy were assessed. RESULTS: Most frequent adverse events were pain, nausea, voice changes and fatigue. Five dose-limiting toxicities (DLTs) occurred: hypertension (cohort I and II), bowel perforation, lipase increase and atrial flutter (cohort III). Cumulative toxicity resulted in a bevacizumab dose reduction to 1 mg/kg (cohort III). Due to three DLTs (n = 14), this cohort represented the best-tolerated dose level. Bevacizumab effectively neutralized plasma VEGF even at 1 mg/kg. Twelve patients had stable disease (clinical benefit 46%). EPC and SDF-1α levels increased during monotherapy telatinib. CONCLUSIONS: Telatinib (450 mg b.i.d.) combined with bevacizumab (1 mg/kg bi-weekly) shows antitumor activity, but accumulating constitutional toxicity impedes long-term treatment of patients. Therefore, this combination will not be pursued in a phase II setting.

Effect of age on the pharmacokinetics of solifenacin in men and women.

OBJECTIVE: The pharmacokinetics of solifenacin succinate (YM905; Vesicare), a new, bladder-selective, muscarinic receptor antagonist for the treatment of overactive bladder in young/middle-aged and elderly subjects were compared. MATERIAL: Solifenacin. METHODS: 47 healthy adults (24 young/middle-aged: mean age 35; and 23 elderly: mean age 68; 12 males in each age group) were enrolled in a single-center, multi-dose, open-label, crossover trial. Solifenacin, 5 or 10 mg, was administered once daily during two 14-day study periods separated by a washout period. Subjects were randomized to one dose in the first period and the other dose in the second period. Primary outcome variables were maximum plasma concentration (C(max)) and area under the curve from time 0 - 24 hours (AUC(0-24)). Secondary parameters included terminal elimination half-life (t1/2), time to C(max) (t(max)), fraction unbound, renal clearance, amount/percent of dose excreted in urine as solifenacin and its metabolites, and trough plasma metabolite concentrations. Adverse events and other safety parameters were also evaluated. RESULTS: Mean C(max) and AUC(0-24) were 16% (90% confidence interval 0.973 - 1.373) and 20% (1.003 - 1.435) higher, respectively, in elderly subjects. Mean t(max) and t1/2 were higher in elderly subjects. In both elderly and younger subjects, increasing the dose from 5 to 10 mg dose proportionally increased C(max), AUC(0- 24), and the amount excreted in urine. As expected, t(max) and t1/2 were not affected. Plasma concentrations and amounts of metabolites excreted in urine also increased dose proportionally. Solifenacin was highly bound to plasma proteins (fraction of the drug unbound in plasma was approximately 0.02), but there was no clear effect of gender or age. Solifenacin 5 or 10 mg once daily for 14 days was well tolerated by all subjects. CONCLUSION: Although C(max) and AUC(0-24) were higher in elderly subjects than in younger subjects and there was a tendency toward longer t(max) and t1/2, these differences were small and not considered clinically relevant. In this study, no consistent safety/tolerability issues were associated with these pharmacokinetic differences and the administration of solifenacin 5 or 10 mg once daily was well tolerated. The number of adverse events in elderly subjects was similar to that in younger subjects, indicating that no age-related dose adjustments are needed with this agent.

Phase I study of MEN-10755, a new anthracycline in patients with solid tumours: a report from the European Organization for Research and Treatment of Cancer, Early Clinical Studies Group.

A phase I study was performed with MEN-10755, a novel anthracycline with promising preclinical antitumour activity, in patients with solid tumours to determine the maximum tolerated dose (MTD); the dose-limiting toxicities (DLTs); to document antitumour activity; and to propose a safe dose for phase II evaluation. MEN-10755 at a starting dose of 15 mg/m2/week was given by short intravenous infusion weekly for 3 weeks and cycles were repeated every 28 days. Twenty-four patients received 55 cycles. Doses of MEN-10755 were 15, 30, 40 and 45 mg/m2. At a dose of MEN-10755 45 mg/m2, treatment could not be given as planned due to neutropenia and one patient developed a decrease in cardiac function. This dose level was considered to be the MTD. Chemotherapy-naive patients could be treated with 40 mg/m2/week, and only one DLT (grade 4 neutropenia) was observed. At that dose, three of six chemotherapy pretreated patients developed a DLT during their first treatment cycle: one patient developed a grade 4 thrombocytopenia, one patient a grade 4 neutropenia and one patient developed a grade 3 acute hypersensitivity reaction resulting in discontinuation of treatment. At this dose level, one other patient did not receive treatment on day 15 as planned due to grade 3 neutropenia. No responses were observed. MEN-107555 at a dose of 30 mg/m2/week in pretreated patients and 40 mg/m2/week in chemotherapy-naive patients for three consecutive weeks followed by 1 week rest is recommended for phase II testing.

Population pharmacokinetic and dynamic analysis of the topoisomerase I inhibitor lurtotecan in phase II studies.

Population pharmacokinetic-dynamic analysis was prospectively integrated in a broad phase II program of lurtotecan (GI147211), a novel camptothecin derived topoisomerase I inhibitor, to determine the population pharmacokinetic profile in a larger population, to estimate individual pharmacokinetic parameters and to investigate relationships with clinical outcome. A sparse sampling method was applied during course one, which involved two sampling time-points. A Bayesian algorithm was used to estimate individual pharmacokinetic parameters, in particular total plasma clearance (CL) and volume of distribution. In total, samples were collected of 109 (63%) of 173 patients. Pharmacokinetic-dynamic evaluation could be carried out successfully in 85 (78%) of the sampled patients. CL of lurtotecan showed substantial variability (mean 87 +/- 28 L/h) and was of the same magnitude as in the phase I studies where full pharmacokinetic curves were used. Residual variability in the population estimate of CL was 9.9%. No significant relationships were observed between exposure parameters and toxicity nor likelihood of tumor response, however the latter relationship may well have been obscured by the heterogeneity of the studied population. Prospective implementation of large scale population pharmacokinetic-dynamic analysis is feasible and important to establish whether interpatient variability in drug exposure is a major determinant of toxicity or activity.

Phase II trial with ISIS 5132 in patients with small-cell (SCLC) and non-small cell (NSCLC) lung cancer. A European Organization for Research and Treatment of Cancer (EORTC) Early Clinical Studies Group report.

Two multicentre phase II trials were designed to determine if tumour responses can be achieved in progressive small-cell lung cancer (SCLC) or non-small cell lung cancer (NSCLC) patients treated with ISIS 5132, an inhibitor of C-raf kinase mRNA expression (CGP 69846A; ISIS Pharmaceuticals Inc, Carlsbad, CA), and to further characterise the safety of the compound. Between August 1998 and November 1999, 26 patients (18 NSCLC, 8 SCLC) were entered. Out of these, 23 were eligible, 22 (18 NSCLC, 4 SCLC) were treated with ISIS 5132 (2 mg/kg/day, 21 days continuous intravenous (i.v.) infusion every 4 weeks) and were evaluable for toxicity and 18 (15 NSCLC, 3 SCLC) were evaluable for efficacy. For the whole group haematological toxicity did not exceed grade 2. One patient experienced a grade 4 increased prothrombin time. Non-haematological toxicity was mild to moderate, with the observation of asthenia and nausea and vomiting. Progressive disease (PD) was diagnosed in 10 patients (8 NSCLC and 2 SCLC). 8 more patients (7 NSCLC, 1 SCLC) were considered as treatment failures. In conclusion, this study using ISIS 5132 with this dose and schedule of administration excludes a 20% response rate with 95% confidence intervals for NSCLC and cannot draw any conclusions for SCLC patients as only a few were involved in the study.

Pharmacokinetics of MEN-10755, a novel anthracycline disaccharide analogue, in two phase I studies in adults with advanced solid tumours.

The doxorubicin analogue MEN-10755 has been identified as a compound with promising antitumour activity based on structure-activity studies of a new series of anthracycline disaccharides. The high antitumour activity of MEN-10755 in human tumour xenografts, including doxorubicin-resistant xenografts, and its unique pharmacological and biological properties made this novel disaccharide analogue an interesting candidate for clinical evaluation. Two pharmacokinetic phase I studies with different dosing schedules were performed in adults with solid refractory malignancies. The pharmacokinetics of MEN-10755 were studied after a 15-min i.v. infusion given once every 3 weeks or once every week for 3 weeks followed by 1 week rest. Plasma and urine levels of MEN-10755 were measured by HPLC with fluorescent detection. It was possible to combine the pharmacokinetic results of the two studies because there was no accumulation of MEN-10755 before the next infusion of MEN-10755 in the weekly study with 1 week rest. The administered dose levels on day 1 in this study were all in the lower range from the 3-weekly study. The postinfusion plasma kinetics of MEN-10755 were best described by a triexponential model. The plasma peak levels (Cmax) of MEN-10755 showed a linear relationship with the administered dose. Peak plasma MEN-10755 levels ranged between 474 and 21,587 microg/l. The mean elimination half-life (T(1/2gamma)) was 20.7+/-9.0 h. The AUC(0-infinity) was proportional to the administered dose. The mean plasma clearance of MEN-10755 was 6.0+/-2.2 l/h per m2 with a mean volume of distribution (Vss) of 95.6+/-43.4 l/m2. The mean renal excretion of unchanged drug within 24 h was 4.3+/-1.8%. Compared to epirubicin and doxorubicin, the pharmacokinetics of MEN-10755 were characterized by an approximately twofold shorter terminal half-life, a much lower total plasma clearance and a much smaller volume of distribution.

Activity and toxicity of GI147211 in breast, colorectal and non-small-cell lung cancer patients: an EORTC-ECSG phase II clinical study.

BACKGROUND: GI147211 is a water-soluble synthetic analogue of camptothecin showing promising in vivo and in vitro antitumor activity and an acceptable toxicity profile. PATIENTS AND METHODS: Between April 1995 and November 1996, 67 eligible patients with pretreated breast cancer (25 patients) and chemo-naïve colorectal (19 patients) and non-small-cell lung cancer (23 patients) were entered into three multicentric, non-randomized phase II trials. Treatment schedule consisted of intravenous GI1147211 administered at a dose of 1.2 mg/m2/day for five consecutive days every three weeks. RESULTS: Hematological toxicity was common with grade 3-4 neutropenia in 54% of patients and neutropenic fever together or not associated with infection in 14.5% of patients. Grade 3-4 thrombocytopenia and grade 2-4 anemia were observed in 20% and in 68% of patients, respectively. Non-hematological toxicity was generally mild to moderate and consisted mainly of gastrointestinal toxicity, asthenia and alopecia. A dose-escalation to 1.5 mg/m2/d was feasible in 17 (25%) patients. The antitumor activity of GI1147211 was moderate in breast cancer patients (3 partial responses (PRs), response rate (RR) 13%) and minimal in non-small cell lung cancer patients (2 PRs, RR 9%). No objective responses were obtained in colorectal patients. CONCLUSIONS: GI147211, at the dose and schedule employed in this study, showed an acceptable safety profile but a modest antitumor activity in the examined tumor types.

Second-line treatment of small-cell lung cancer with the camptothecin-derivative GI147211: a study of the EORTC Early Clinical Studies Group (ECSG).

BACKGROUND: GI147211, a 10,11-ethylenedioxy substituted analogue of camptothecin (CPT), was brought into clinical development because of its higher water solubility and greater potency as compared to topotecan (TPT). The antitumor activity of GI147211 as second-line therapy in small-cell lung cancer (SCLC) was assessed after stratification of patients in refractory (no response to initial treatment or relapse within three months from last cycle) and chemosensitive (relapse more than three months from last cycle). PATIENTS AND METHODS: Sixty-seven patients were entered in the study and sixty-two were evaluable for response, twenty-eight in the refractory and thirty-four in the chemosensitive group. All patients had received 1 line of chemotherapy; radiation had also been given in 29 cases, 6 in the refractory and 23 in the chemosensitive group. GI147211 was administered at 1.2 mg/m2/day as 30-min infusion for five consecutive days every three weeks. RESULTS: The overall response rate was 16.6% (11 of 66 patients; 95% confidence interval (95% CI): 8.5%-27.5%), 10.3% (3 of 29 patients; 95% CI: 2.2%-27%) in the refractory and 21.1% (8 of 37 patients; 95% CI: 9.5%-37%) in the chemosensitive group. Only partial responses (PR) were observed with a median duration of PR of 4.8 months (5.7 months in the refractory and 5.2 in the chemosensitive group). Hematological toxicity consisted mainly of neutropenia (grades 3-4 in 25% of cycles) and thrombocytopenia (grades 3-4 in 23% of cycles); non-hematological toxicity was mild to moderate and consisted of nausea (22% of cycles), vomiting (11%), malaise (34%). CONCLUSIONS: At the dose and schedule tested GI147211 is an active new agent for second-line treatment of SCLC; the antitumor activity and toxicity profile are comparable to those observed with TPT which remains the leading CPT analogue for salvage treatment. Interest has been renewed in the clinical development of GI147211 by preclinical data with the liposomal formulation showing an increased therapeutic index.

Effect of anti-neutrophil cytoplasmic antibodies on proteinase 3-induced apoptosis of human endothelial cells.

Wegener's granulomatosis is characterized by crescentic necrotizing glomerulonephritis and systemic vasculitis. Both proteinase 3 (PR3) and anti-neutrophil cytoplasmic antibodies (ANCA), directed against this enzyme, are thought to play a pathogenic role. PR3 has been shown to cause detachment and cytolysis of human umbilical vein endothelial cells (HUVEC) in vitro and to induce apoptosis of bovine pulmonary artery endothelial cells. In the present study we investigated the effect of PR3 and ANCA on the induction of apoptosis of human endothelial cells in vitro. HUVEC were cultured in the absence or presence of varying concentrations of PR3 for different time periods and apoptosis was assessed by three different methods. Staining of the cells with Hoechst 33258 and assessment of nuclear morphology by ultraviolet (UV) light microscopy revealed a dose-dependent induction of apoptosis, as determined by cell counts. A concentration of 8 microg/ml PR3 was found to induce 16% apoptosis after 16 h incubation. Analysis of apoptosis by flow cytometry using the terminal deoxynucleotidyl transferase-mediated dUTP-fluorescein nick-end labelling (TUNEL) method also demonstrated a dose-dependent induction of apoptosis by PR3. DNA fragmentation was confirmed by agarose gel electrophoresis. To investigate the effect of ANCA on PR3-mediated apoptosis, HUVEC were exposed to immunoglobulin G (IgG) from patients with Wegener's granulomatosis or systemic vasculitis, and from normal controls, in the presence or absence of PR3. Enhancement of PR3-mediated apoptosis was found in two of 10 IgG samples with anti-PR3 activity, whereas a reduction in apoptosis was observed in two others. Anti-MPO (myeloperoxidase)-positive IgG, six additional anti-PR3 positive IgG samples and control IgG samples did not have any detectable effect on apoptosis. These studies suggest that ANCA may modulate the relative degree of injury in some cases of Wegener's granulomatosis.

Phase II trial of the oral platinum complex JM216 in non-small-cell lung cancer: an EORTC early clinical studies group investigation.

BACKGROUND: JM216 is a new oral platinum complex with dose-limiting toxicity myelosuppression, now undergoing phase II evaluation. PATIENTS AND METHODS: JM216 was evaluated as first line therapy in non-small-cell lung cancer. Seventeen patients received 120 mg/m2/day for five days repeated every three weeks. RESULTS: Toxicity was manageable, the commonest side-effects being nausea, vomiting, diarrhoea, constipation and asthenia. Myelososuppression was generally grade < 2 and there were no cases of neutropenic sepsis or bleeding. Thirteen patients were fully evaluable for response. No sustained objective responses were reported. One patient was reported as stable disease had a partial response after three courses but was progressing again after four. An additional five patients had stable disease (46.2%). CONCLUSIONS: Although some patients may have had useful palliation, JM216 did not appear to have significant antitumour activity in non-small-cell lung cancer.

Analgesic and spasmolytic effects of dipyrone, hyoscine-N-butylbromide and a combination of the two in ponies.

The analgesic and spasmolytic effects of dipyrone (Novalgin) (2500 mg/100 kg bodyweight) hyoscine-N-butylbromide (Buscopan) (20 mg/100 kg bodyweight) and a combination of both drugs were evaluated in a balloon-induced model of colic, using five ponies with caecal fistulae. The drugs were given intravenously and 0.9 per cent sodium chloride solution (5 ml/100 kg bodyweight) was used as a control. The physiological saline solution and dipyrone had no effect on caecal contractions. After the injection of hyoscine-N-butylbromide and the drug combination caecal contractions ceased within 30 seconds and for 20 and 24 minutes, respectively (P less than 0.05). The results on pain relief were not statistically significant for any of the drugs. Dipyrone had a good analgesic effect in only two of the ponies, starting after eight to 10 minutes and lasting for 50 minutes. The drug combination relieved pain within 30 seconds after injection and the relief lasted for 50 minutes in three of the ponies and for 20 minutes in the other two. Hyoscine-N-butylbromide alone produced an analgesic effect within 30 seconds after injection which lasted for 20 minutes.

Aujeszky's disease in horses fulfils Koch's postulates.

Aujeszky's disease virus was isolated from the brain of a horse which had shown severe neurological signs, including excessive sweating, muscle tremors and periods of mania. Pathological examination revealed a non-suppurative meningoencephalitis. The virus was propagated in cell culture and inoculated into the conjunctiva and nostrils of two ponies. The ponies developed fever seven days after inoculation and subsequently started to behave abnormally, showing severe neurological signs on the ninth day after inoculation. One pony became excited and the other was depressed. One pony died on the ninth day after inoculation and the other was euthanased on the 10th day. Both ponies had a significant increase in serum antibody titre against the virus. The virus was recovered from several parts of the brains and the eyes of the ponies. Aujeszky's disease in horses therefore fulfils Koch's postulates. Although horses do not appear to be very susceptible to the virus, Aujeszky's disease should be included in the differential diagnosis of horses with fatal or transient neurological signs of disease in areas where the virus is endemic.