Suppression of Inflammatory and Fibrotic Signals by Cinnamon (Cinnamomum cassia) and Cinnamaldehyde in Cyclophosphamide-Induced Overactive Bladder in Mice

Cinnamon (Cinnamomum cassia) is a well-known traditional Chinese medicine used to treat nocturia by tonifying and warming the kidney. Our recent clinical study found that overactive bladder (OAB) patients treated with cinnamon powder (CNP) patches exhibited significantly ameliorated OAB symptoms without significant side effects, but the mechanism of action is unclear. To explore the beneficial effects and action mechanisms of CNP and its major active component cinnamaldehyde (CNA) in an OAB-related murine model, cyclophosphamide- (CYP-) induced OAB injury was performed on male ICR mice in the presence or absence of CNP and CNA, as well as solifenacin, a clinical drug for OAB as a reference. Twenty-four-hour micturition patterns (frequency of urination and volume of urine per time), as well as histopathological examination, immunohistochemistry (IHC), and Western blotting of the bladder, were analyzed for mechanism elucidation. Administration of CYP (300 mg/kg, i.p.) induced typical OAB pathophysiological changes, including increased frequency of urination and reduced volume of urine. CYP-induced mice displayed strong edema of the bladder and hemorrhagic cystitis, accompanied by loss of normal corrugated folds and decreased muscarinic receptors (M2/M3) in the urothelium, and disordered/broken structures of the lamina propria and detrusor. These changes were correlated with increased leukocyte (CD11b) infiltration colocalized with inflammatory (pp65 NFκB, macrophage migration inhibitory factor (MIF)/Toll-like receptor 4 (TLR4)) and fibrotic (stem cell factor (SCF)/c-Kit, α-smooth muscle actin (α-SMA)/β-catenin) signals. Treatment with CNP (600 mg/kg, p.o.) and CNA (10–50 mg/kg, p.o.), but not solifenacin (50 mg/kg), 30 min after CYP induction significantly ameliorated CYP-induced dysfunction in micturition patterns and pathophysiological changes. CNP and CNA further suppressed MIF/TLR4-associated inflammatory and SCF/c-Kit-related fibrotic signaling pathways. Our findings indicate that suppression of inflammatory and fibrotic signals contributes to the crucial mechanism in the improvement of CYP-induced OAB by CNP and CNA.

Clarithromycin–rifampin-based treatment for nontuberculous mycobacteria infections in immunocompromised patients who require concomitant CYP-metabolized medications

Clarithromycin (CYP inhibitor) can be used instead of azithromycin for nontuberculous mycobacteria therapy in patients requiring CYP-substrates, to mitigate rifampin’s CYP induction. We found no differences in adverse events (10/13 vs. 14/17; p=0.73), drug intolerability (1/5 vs. 4/11; p=1), or 90-day mortality (0/13 vs. 1/17; p=1) in patients receiving clarithromycin vs. azithromycin

1399. Clarithromycin–Rifampin-based Treatment for Non-tuberculous Mycobacterial Infections in Immunocompromised Patients Who Require Concomitant CYP-Metabolized Medications

Background Non-tuberculous mycobacteria (NTM) are causes of pulmonary and extrapulmonary disease that frequently affect immunocompromised hosts (ICH). Current treatment guidelines recommend a macrolide-based, multi-drug regimen that includes rifampin. Rifampin is a potent cytochrome P450 (CYP) 3A inducer, which often results in drug-drug interactions in ICH receiving multiple CYP substrates. One way to mitigate rifampin’s CYP induction is to utilize clarithromycin, a CYP inhibitor, as the accompanying macrolide. We evaluated the incidence of NTM treatment-related adverse events (AEs) in patients who received a clarithromycin-based regimen compared to patients who received an azithromycin-based regimen. Methods We conducted a retrospective review of NTM infection in 30 immunocompromised adults. All participants had a positive culture for a NTM and had received a rifamycin (rifampin or rifabutin) with a macrolide (azithromycin or clarithromycin) for treatment at Brigham and Women’s Hospital between 01/01/2011-10/18/2020 or Dana-Farber Cancer Institute between 06/03/2015-07/01/2020. The primary outcome was the incidence of NTM treatment-related AEs in patients who received a clarithromycin-based regimen compared to those who received an azithromycin-based regimen. Results There were no significant differences in the reasons for discontinuation of NTM treatment or 90-day mortality between groups. The number of AEs possibly related to NTM treatment were similar in patients who received a clarithromycin-based regimen and those who received an azithromycin-based one (10/13 vs. 14/17; p=0.73). The most common AE was liver function test abnormalities (Table 1). Additionally, the proportion of patients requiring dose adjustments for interacting medications and patients with out-of-range tacrolimus levels were similar between the two groups (23.1% vs. 29.4%; p=0.76 and 8.0% vs. 6.0%; p=1.00, respectively). Table 1: Adverse events Conclusion A clarithromycin-based regimen for NTM treatment was safe and well tolerated in our patient population. This combination provides a good alternative for patients requiring medications that are CYP substrates, or those who cannot tolerate azithromycin. Disclosures Matthew Cheng, MD, GEn1E Lifesciences (Advisor or Review Panel member)Kanvas Biosciences (Board Member, Shareholder)nplex biosciences (Advisor or Review Panel member)

Pharmacokinetic Estimation Models-based Approach to Predict Clinical Implications for CYP Induction by Calcitriol in Human Cryopreserved Hepatocytes and HepaRG Cells

Calcitriol, a vitamin D3 metabolite, is approved for various indications because it is the bioactive form of vitamin D in the body. The purpose of this study was to predict the clinical significance of cytochrome P450 (CYP) induction by calcitriol using in vitro human cryopreserved hepatocytes, HepaRG experimental systems, and various pharmacokinetic estimation models. CYP2B6, 3A4, 2C8, and 2C9 mRNA levels increased in a concentration-dependent manner in the presence of calcitriol in human cryopreserved hepatocytes and HepaRG cells. Using the half maximal effective concentration (EC50) and maximum induction effect (Emax) obtained from the in vitro study, a basic kinetic model was applied, suggesting clinical relevance. In addition, a static mechanistic model showed the improbability of a clinically significant effect; however, the calculated area under the plasma concentration–time curve ratio (AUCR) was marginal for CYP3A4 in HepaRG cells. To clarify the effect of CYP3A4 in vivo, physiologically based pharmacokinetic (PBPK) modeling was applied as a dynamic mechanistic model, revealing a low clinically significant effect of CYP3A4 induction by calcitriol. Therefore, we conclude that CYP induction by calcitriol treatment would not be clinically significant under typical clinical conditions.

Inhibition and induction of CYP enzymes in humans: an update

The cytochrome P450 (CYP) enzyme family is the most important enzyme system catalyzing the phase 1 metabolism of pharmaceuticals and other xenobiotics such as herbal remedies and toxic compounds in the environment. The inhibition and induction of CYPs are major mechanisms causing pharmacokinetic drug–drug interactions. This review presents a comprehensive update on the inhibitors and inducers of the specific CYP enzymes in humans. The focus is on the more recent human in vitro and in vivo findings since the publication of our previous review on this topic in 2008. In addition to the general presentation of inhibitory drugs and inducers of human CYP enzymes by drugs, herbal remedies, and toxic compounds, an in-depth view on tyrosine-kinase inhibitors and antiretroviral HIV medications as victims and perpetrators of drug–drug interactions is provided as examples of the current trends in the field. Also, a concise overview of the mechanisms of CYP induction is presented to aid the understanding of the induction phenomena.

ERRATUM

Testing drugs in isogenic rodent strains to satisfy regulatory requirements is insufficient for derisking organ toxicity in genetically diverse human populations; in contrast, advances in mouse genetics can help mitigate these limitations. Compared to the expensive and slower in vivo testing, in vitro cultures enable the testing of large compound libraries toward prioritizing lead compounds and selecting an animal model with human-like response to a compound. In the case of the liver, a leading cause of drug attrition, isolated primary mouse hepatocytes (PMHs) rapidly decline in function within current culture platforms, which restricts their use for assessing the effects of longer-term compound exposure. Here we addressed this challenge by fabricating mouse micropatterned cocultures (mMPCC) containing PMHs and 3T3-J2 murine embryonic fibroblasts that displayed 4 weeks of functions; mMPCCs created from either C57Bl/6J or CD-1 PMHs outperformed collagen/Matrigel™ sandwich-cultured hepatocyte monocultures by ∼143-fold, 413-fold, and 10-fold for albumin secretion, urea synthesis, and cytochrome P450 activities, respectively. Such functional longevity of mMPCCs enabled in vivo relevant comparisons across strains for CYP induction and hepatotoxicity following exposure to 14 compounds with subsequent comparison to responses in primary human hepatocytes (PHHs). In conclusion, mMPCCs display high levels of major liver functions for several weeks and can be used to assess strain- and species-specific compound effects when used in conjunction with responses in PHHs. Ultimately, mMPCCs can be used to leverage the power of mouse genetics for characterizing subpopulations sensitive to compounds, characterizing the degree of interindividual variability, and elucidating genetic determinants of severe hepatotoxicity in humans.