Activated T cells also induce apoptosis in hematopoietic stem cells.Aplastic anemia is associated with increased levels of Th17 cells—which produce pro-inflammatory cytokine IL-17—and interferon-γ-producing cells in the peripheral blood and bone marrow. Th17 cell populations also negatively correlate with regulatory T-cell populations, suppressing auto-reactivity to normal tissues, including the bone marrow. Deep phenotyping of regulatory T-cells showed two subpopulations with specific phenotypes, gene expression signatures, and functions.Studies in patients who responded to immunosuppressive therapy found dominant subpopulations characterized by higher expression of HLA‐DR2 and HLA‐DR15 (mean age of two groups: 34 and 21 years), FOXP3, CD95, and CCR4; lower expression of CD45RA (mean age: 45 years); and expression of the IL‐2/STAT5 pathway. Higher frequency of HLA‐DR2 and HLA‐DR15 may cause augmented presentation of antigens to CD4+ T-cells, resulting in immune‐mediated destruction of the stem cells. In addition, HLA‐DR2-expressing cells augment the release of tumor necrosis factor-α, which plays a role in disease pathology.The hypothesis of aberrant, disordered T‐cell populations as the initiators of aplastic anemia is supported by findings that immunosuppressive therapy for T-cells (for example, anti-thymocyte globulin and ciclosporin) results in a response in up to 80% of severe aplastic anemia patients. CD34+ progenitor cells and lymphocytes in the bone marrow over-express the Fas receptor, the main element in apoptotic signaling. A significant increase in the proportion of apoptotic cells in the bone marrow of aplastic anemia patients has been demonstrated.
The major metabolic pathway is hypothesized as ester hydrolysis with subsequent conjugation of benzylic acid to form azoniaspironortropanol with glucuronic acid. Cytochrome P450 is not expected to contribute significantly to the elimination of trospium. Data taken from in vitro human liver microsomes investigating the inhibitory effect of trospium on seven cytochrome P450 isoenzyme substrates (CYP1A2, 2A6, 2C9, 2C19, 2D6, 2E1, and 3A4) suggest a lack of inhibition at clinically relevant concentrations.The plasma half-life for trospium chloride following oral administration is approximately 20 hours. After oral administration of an immediate-release formulation of 14C-trospium chloride, the majority of the dose (85.2%) was recovered in feces and a smaller amount (5.8% of the dose) was recovered in urine; 60% of the radioactivity excreted in urine was unchanged trospium. The mean renal clearance for trospium (29 L/hour) is 4-fold higher than average glomerular filtration rate, indicating that active tubular secretion is a major route of elimination for trospium. There may be competition for elimination with other compounds that are also renally eliminated. Chemical properties
Anticholinergic drugs used to treat overactive bladder were all amines as of 2003. Quaternary ammonium cations in general are more hydrophilic than other amines and dont cross membranes well, so they tend to be poorly absorbed from the digestive system, and to not cross the blood-brain barrier. Oxybutynin, tolterodine, darifenacin, and solifenacin are tertiary amines while trospium chloride and propantheline are quaternary amines.