Stereoselectivity of idarubicin reduction in various animal species and humans

1. The (13S)-dihydro derivative of idarubicin, (13S)-idarubicinol, is the major urinary metabolite of idarubicin in humans. Idarubicinol epimers were quantified by h.p.l.c. in urine from rats, mice, rabbits, dogs and man after i.v. administration of idarubicin, and in man after oral dosing. The (13R)- and (13S)-epimers of idarubicinol were determined in rat bile. 2. After i.v. injection of idarubicin. (13R)-idarubicinol was not detectable in mice and rabbit urine and no more than 0.5% of the dose was present in the urine of other species. In man, the proportion of (13R)-idarubicinol in total idarubicinol was similar after i.v. (4.1%) and oral (3.8-5.0%) administration of idarubicin; the same applies to rat bile and urine. 3. Reduction of idarubicin in vivo is dependent upon ketone reductases, and proceeds more stereoselectively than that of most ketones giving rise to the (13S)-epimer almost exclusively. The high stereospecificity in idarubicin reduction might result from chiral induction due to the presence of asymmetric centres near to the carbonyl group in idarubicin.     

Lower urinary tract symptoms and sexual dysfunction in women

This article assesses the effects of lower urinary tract symptoms (LUTS), not including urinary incontinence, on the overall sexual health of women, using literature that includes peer-reviewed articles. This article analyzes a number of studies that provide data on the prevalence and the predictors of sexual function impairment in women with LUTS, such as urinary urgency and frequency, overactive bladder syndrome, and interstitial cystitis. Because case studies provide substantial heterogeneity of outcome measures, this article does not apply meta-analytic techniques to the data. Most of the studies showed that LUTS can have a negative impact on the sexual health of women, sexual pain disorder being the more frequent complaint among patients with bladder dysfunctions.     

Pharmacokinetic and pharmacodynamic modelling of metoprolol in rabbits with liver failure

The pharmacokinetic and pharmacodynamic profiles of metoprolol were studied in adult male rabbits given 3.2 mg/kg i.v. before and during liver failure. The partition of metoprolol between blood cells and plasma averaged 1.14 in both conditions. Plasma protein binding, concentration-independent, was 32% and 17% in normal and pathological status, respectively. With normal liver function the terminal elimination half-life for the drug was 0.54-0.96 h, rising to 1.0-2.1 h in liver failure. Differences of the same order were observed for total plasma drug clearance (average 3.7 vs 1.5 1/h/kg), MRT (0.77 vs 1.92 h), AUC (0.9 vs 2.2 mg h/l) and k10 (3.17 vs 1.80 h-1). Liver impairment did not affect the volume of distribution of the central compartment, the steady-state volume of distribution and the other intercompartmental rate constants. Although metoprolol was eliminated in the urine, the amount excreted was low (1.5% of the administered dose) in both conditions. The pharmacokinetic model was extended by an 'effect compartment', which has no influence on the predetermined mass of drug in the body, to analyse the relationship between heart rate fall and changes in metoprolol plasma concentrations. After drug administration, heart rate fell rapidly about 90 beats in both states. The mean unbound plasma concentration producing 50% of this reduction was double during liver failure compared to normal condition (0.03 vs 0.07 mg/l), but the temporal aspects of drug equilibration with site of action were similar.     

Endovascular repair for concomitant multilevel aortic disease.

OBJECTIVE: Patients with multilevel aortic disease represent a small subgroup with the need for extensive surgical treatment at considerable risk. We present our experience of endovascular exclusion for simultaneous thoracic and abdominal aortic disease in four patients. METHODS: Between January 2002 and January 2005, four patients underwent endovascular repair for simultaneous thoracic and abdominal aortic disease. Mean age was 69+/-10 years (range, 60-81). Thoracic lesions included penetrating aortic ulcer (n=2, ruptured=1), atherosclerotic aneurysm (n=1), and chronic type B dissection (n=1). Abdominal aortic disease included atherosclerotic infrarenal (n=3) and juxtarenal (n=1) aortic aneurysms. Thoracic aortic stent-grafts had been the following: Excluder/TAG (n=3) or Talent (n=1) straight tube devices. Abdominal aortic stent-grafts used were as following: Excluder (n=3) or Zenith (n=1). All patients were followed-up with CT-angiography and chest X-rays 1, 4, 12 months after the procedure, and once per year thereafter. RESULTS: Stent-graft deployment was technically successful in all cases. Intraoperative mortality was not observed. Mean procedure time was 94+/-34 min (range, 70-145). Early postoperative complications occurred in one patient that developed acute renal failure but dialysis was not required. Mean hospitalisation was 8+/-5 days (range, 4-15). Late death occurred in one patient for an undetected ruptured thoracic type 1 endoleak. All three survivors are currently well 16.5 months (range, 3-36) after surgery. No neurological complications developed. CONCLUSION: Simultaneous abdominal and thoracic endovascular repair for multilevel aortic disease is feasible and could be a viable alternative in high-risk patients, who otherwise may not be suitable candidates for conventional repair.     

Pharmacokinetics of reboxetine in healthy volunteers. Single oral doses,linearity and plasma protein binding

The pharmacokinetics of reboxetine, a new antidepressant agent, were found to be close to linear in a crossover study comparing administration of single 2, 3, 4 and 5 mg capsule doses in 15 healthy male volunteers, and in the same study the capsules were bioequivalent to the proposed therapeutic tablet formulation (4mg). Kinetic analysis was based on HPLC assay of reboxetine in plasma and urine collected up to 72 h after each administration. Plasma levels indicated a rapid absorption (t_max?2h) and an elimination half-life of about 13 h. Clearance and volume of distribution were modest (ratios to bioavailability: CL/F?29 mL min^?1; V_z/F?32L); urinary excretion was ～9% of dose, corresponding to a renal clearance of only 3 mL min^?1 (a value consistent with the rate of glomerular filtration of unbound drug). In vitro, binding to plasma proteins, estimated from radioactivity levels following dialysis of ¹⁴C-labelled reboxetine, appeared to be dominated by α₁-acid glycoprotein without marked saturation up to plasma concentrations of over 500 ng mL^?1 (2.8–3.1% unbound with human plasma from three additional volunteers; 1.8–2.0% for 2gL^?1 orosomucoid α₁-acid glycoprotein, and 46.4–47.4% for 40 gL^?1 albumin), whilst the mean C_max in the current study was much lower (164 ng mL^?1 after a 5 mg dose).