Journal of pharmacological sciences
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Cav3.2 T-type Ca(2+) channels targeted by H2S, a gasotransmitter, participate in cyclophosphamide-induced cystitis and bladder pain. Given that zinc selectively inhibits Cav3.2 among T-channel isoforms and also exhibits antioxidant activity, we examined whether polaprezinc (zinc-l-carnosine), a medicine for peptic ulcer treatment and zinc supplementation, reveals preventive or therapeutic effects on bladder inflammation and/or pain in the mouse with cyclophosphamide-induced cystitis, a model for interstitial cystitis. Systemic administration of cyclophosphamide caused cystitis-related symptoms including increased bladder weight and vascular permeability, and histological signs of bladder edema, accompanied by bladder pain-like nociceptive behavior/referred hyperalgesia. ⋯ The same dose of polaprezinc also prevented the increased malondialdehyde level, an indicator of lipid peroxidation, and protein upregulation of cystathionine-γ-lyase, an H2S-generating enzyme, but not occludin, a tight junction-related membrane protein, in the bladder tissue of cyclophosphamide-treated mice. Oral posttreatment with polaprezinc at 30-100 mg/kg reversed the nociceptive behavior/referred hyperalgesia in a dose-dependent manner without affecting the increased bladder weight. Together, our data show that zinc supplementation with polaprezinc prevents the cyclophosphamide-induced cystitis probably through the antioxidant activity, and, like T-channel blockers, reverses the established cystitis-related bladder pain in mice, suggesting novel therapeutic usefulness of polaprezinc.
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A hybrid pharmacokinetic/pharmacodynamic (PK/PD) model with extended-release (ER) process and target mediated drug disposition (TMDD) was developed for exenatide ER to account for its complex absorption process and glucagon-like peptide 1 receptor (GLP-1R)-mediated non-linear PK behaviors along with its influences to fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c). Using hybrid PK/PD model, simulations were done to explore the potential dosing regimens which could achieve likelihood of more pharmacodynamic exposure with respect to FPG and HbA1c over a much shorter period compared with the currently used treatment protocol. ⋯ Monte Carlo simulation was applied to mimic the PK profiles when higher loading dose 7.5 and 5.0 mg exenatide ER were subcutaneously administrated with different dosing intervals at the first 3 weeks of 30-week treatment. Two potentially optimizing schedules could improve the likelihood of achieving much more FPG and HbA1c exposures than currently used clinical treatment protocol.