Cyclosporin metabolites and neurotoxicity

Cyclosporine A alleviated matrix metalloproteinase 9 associated blood-brain barrier disruption after subarachnoid hemorrhage in mice

The aim of this study was to investigate whether Cyclosporine A (CsA) attenuates early brain injury by alleviating matrix metalloproteinase 9 (MMP-9) associated blood-brain barrier (BBB) disruption after subarachnoid hemorrhage (SAH). A standard intravascular perforation model was used to produce the experimental SAH in C57B6J mice. Dosages of 5mg/kg, 10mg/kg and 15mg/kg CsA were evaluated for effects on neurological score, brain water content, Evans blue extravasation and fluorescence, P-p65, MMP-9 and BBB components' alterations after SAH. We found that CsA 15mg/kg is effective in attenuating BBB disruption, lowering edema, and improving neurological outcomes. In addition, Collagen IV, ZO-1, Occludin and Claudin 5 expressions in ipsilateral/left hemisphere were downregulated after SAH, but increased after CsA treatment. Our results suggest that CsA exert a neuroprotective role in SAH pathophysiology, possibly by alleviating MMP-9 associated BBB disruption.

Neurotoxicity of commonly used hepatic drugs

Neurologic complications are common side-effects of immunosuppressive medications used in the prevention of graft rejection after organ transplantation. The medications most commonly encountered include the calcineurin inhibitors and mycophenolate mofetil. Depression is the most commonly encountered neurotoxicity; however, severe but rare adverse neurological effects related to these therapies have been reported. Interferons, ribavirin, and protease inhibitors are therapeutic options commonly encountered in the treatment of hepatitis. Nucleoside analogs such as adefovir dipivoxil and entecavir carry significant risks for the development of lactic acidosis and hepatic dysfunction; however, most common adverse effects to these therapies in general are mild. While the mechanisms of action are poorly elucidated, they are discussed along with treatment strategies.

Cyclosporine pharmacokinetics in liver transplant recipients: evaluation of results using both polyclonal radioimmunoassay and liquid chromatographic analysis

Pharmacokinetic variables were derived from cyclosporine measurements using liquid chromatography (HPLC) and radioimmunoassay with a non-selective polyclonal antibody (PARIA) in 11 orthotopic liver transplant recipients studied in paired oral and intravenous studies both before and after permanent clamping of the biliary T-tube. After oral drug administration, mean areas under blood cyclosporine concentration versus time curves before clamping were around 5.2-fold greater by PARIA than HPLC but 2.9-fold greater after clamping and closer to comparable values after intravenous cyclosporine (2.5 and 2.3-fold, respectively). Cyclosporine clearance was smaller by PARIA than HPLC (mean 7.3 versus 3.3 ml.min-1.kg-1, respectively, before clamping). Both values decreased by 25% after clamping (to 5.5 and 2.4 ml.min-1.kg-1, respectively), although there was no significant change in distribution or elimination half-lives (around 0.5 and 8 h, respectively). The mean bioavailability of oral cyclosporine increased significantly after clamping in 9 patients (from 10.6% to 28.1% by HPLC and from 14.8 to 35.1% by PARIA) but in two patients who developed the vanishing bile duct syndrome values fell to less than 10% and the proportional overestimation of cyclosporine concentrations by PARIA increased. Clamping had no singificant effect on the mean apparent volumes of distribution but values of Vz were approximately twice those of Vss (around 2.6 and 1.31.kg-1 by PARIA and HPLC respectively). Mean half lives after clamping were shorter following oral than intravenous cyclosporine (t 1/2 lambda 2 around 15 h enterally versus 8 h parenterally).(ABSTRACT TRUNCATED AT 250 WORDS)

Laboratory monitoring of cyclosporine levels: guidelines for the dermatologist

The following guidelines are recommended for laboratory monitoring of circulating levels of cyclosporine in dermatology patients. Measurements should be determined as trough levels in whole blood, not plasma or serum. The measurements should be performed with an assay that is specific for the parent cyclosporine compound (e.g., a high-performance liquid chromatography method or a specific monoclonal immunoassay). The results of nonspecific immunoassays that detect cyclosporine as well as its metabolites are difficult to interpret and cannot readily be compared among different studies or laboratories. In psoriasis patients, the circulating concentration of cyclosporine does not correlate reliably with the therapeutic response. Some patients may achieve an excellent response with blood levels in the range of 50 ng/ml; others may show little or no response despite blood levels as high as 200 ng/ml. In patients with a poor clinical response, monitoring of cyclosporine levels may be useful to confirm that the drug has been taken and may provide an estimate of the degree of absorption and metabolism of the parent compound. Because an upper limit of safety for the circulating concentration of cyclosporine has not been clearly defined, one should attempt to achieve a therapeutic response with the lowest possible dose. Clinicians must carefully monitor patients for signs of cyclosporine toxicity, regardless of the circulating concentration of the drug. Whole blood levels exceeding 250 ng/ml should be avoided.