Oral absorption of propiverine solution and of the immediate and extended release dosage forms: influence of regioselective intestinal elimination

Establishment of human intestinal organoids derived from commercially available cryopreserved intestinal epithelium and evaluation for pharmacokinetic study

Human intestinal organoids (HIOs) have been reported to exert their functions in a way that mimics living organs, and HIOs-derived monolayers are expected to be applied to in vitro intestinal pharmacokinetic studies. However, HIOs are established from human tissue, which raises issues of availability and ethics. In the present study, to solve these problems, we have established intestinal organoids using commercially available cryopreserved human intestinal epithelial cells (C-IOs), and compared their functions with biopsy-derived human intestinal organoids (B-IOs) from a pharmacokinetic point of view. Both C-IOs and B-IOs reproduced the morphological features of the intestinal tract and were shown to be composed of epithelial cells. Monolayers generated from C-IOs and B-IOs (C-IO-2D, B-IO-2D, respectively) structurally mimic the small intestine. The C-IOs showed gene expression levels comparable to those of the B-IOs, which were close to those of adult human small intestine. Importantly, the C-IOs-2D showed levels of pharmacokinetics-related protein expression and activity-including cytochrome P450 3A4 (CYP3A4) and carboxylesterase 2 (CES2) enzymatic activities and P-glycoprotein (P-gp) transporter activities -similar to those of B-IOs-2D. This study addresses the difficulties associated with B-IOs and provides fundamental characteristics for the application of C-IOs in pharmacokinetic studies.

Dependence of Bioavailability on Mean Absorption Time: What Does It Tell Us?

The extent and rate of bioavailability are fundamental measures to characterize the pharmacokinetics of drugs after oral administration. Together with bioavailability (F), the mean absorption time (MAT) can be used to define the rate of bioavailability, i.e., the rate of drug absorption. Previous results suggest that F may depend on MAT. Estimates of F and MAT were obtained from the input function (sum of two inverse Gaussian functions) used to model the oral absorption process. The estimation was performed by population analysis (nonlinear mixed-effects modeling) based on data from bioavailability studies in healthy volunteers. For trospium and ketamine, F decreased significantly with increasing MAT, while for propiverine, a significant increase was observed. Thus, the interindividual variability in F could be largely attributed to the interindividual variability in MAT. For trospium and propiverine, the relative dispersion (normalized variance) of the absorption time distribution increased significantly with MAT. For trospium and propiverine, the plot of F versus MAT provides information about the effect of gastrointestinal transit on drug absorption. In contrast, an increase in hepatic extraction with increasing MAT is responsible for the dependence of F on MAT. The F versus MAT plot is suggested as a simple diagnostic tool in evaluating the results of bioavailability studies.

Expression of clinically relevant drug-metabolizing enzymes along the human intestine and their correlation to drug transporters and nuclear receptors: An intra-subject analysis

The oral bioavailability of many drugs is highly influenced not only by hepatic but also by intestinal biotransformation. To estimate the impact of intestinal phase I and II metabolism on oral drug absorption, knowledge on the expression levels of the respective enzymes is an essential prerequisite. In addition, the potential interplay of metabolism and transport contributes to drug disposition. Both mechanisms may be subjected to coordinative regulation by nuclear receptors, leading to unwanted drug-drug interactions due to induction of intestinal metabolism and transport. Thus, it was the aim of this study to comprehensively analyse the regional expression of clinically relevant phase I and II enzymes along the entire human intestine and to correlate these data to expression data of drug transporters and nuclear receptors of pharmacokinetic relevance. Gene expression of 11 drug-metabolizing enzymes (CYP2B6, 2C8, 2C9, 2C19, 2D6, 3A4, 3A5, SULT1A, UGT1A, UGT2B7, UGT2B15) was studied in duodenum, jejunum, ileum and colon from six organ donors by real-time RT-PCR. Enzyme expression was correlated with expression data of the nuclear receptors PXR, CAR and FXR as well as drug transporters observed in the same cohort. Intestinal expression of all studied metabolizing enzymes was significantly higher in the small intestine compared to colonic tissue. CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP3A4/5, SULT1A, UGT1A and UGT2B7 expression increased from the duodenum to jejunum but was markedly lower in the ileum. In the small intestine, that is, the predominant site of drug absorption, the highest expression has been observed for CYP3A4, CYP2C9, SULT1A and UGT1A. In addition, significant correlations were found between several enzymes and PXR as well as ABC transporters in the small intestine. In conclusion, the observed substantial site-dependent intestinal expression of several enzymes may explain regional differences in intestinal drug absorption. The detected correlations between intestinal enzymes, transporters and nuclear receptors provide indirect evidence for their coordinative expression, regulation and function in the human small intestine.

Identification of d-amino acid oxidase and propiverine interaction partners and their potential role in the propiverine-mediated nephropathy

Propiverine, a frequently-prescribed pharmaceutical for the treatment of symptoms associated with overactive bladder syndrome, provoked massive intranuclear and cytosolic protein inclusions in rat proximal tubule epithelium, primarily consisting of the peroxisomal targeting signal 1 (PTS1) containing protein d-amino acid oxidase (DAAO). As this type of nephropathy was also observed for other drugs, the aim was to determine whether propiverine interferes with trafficking and/or import of peroxisomal proteins. To elucidate this, DAAO- and propiverine-specific interaction partners from human HEK293 and rat WKPT cell lines and rat kidney and liver homogenate were determined using co-immunoprecipitation with subsequent nano-ESI-LC-MS/MS analyses. Corroboration of the role of DAAO- and/or propiverine-specific interaction partners in the drug-induced DAAO accumulation was sought via specific immunofluorescence staining of rat kidney sections from control and propiverine-treated rats. Above analyses demonstrated the interaction of propiverine with several protein classes, foremost peroxisomal proteins (DAAO, MFE2, HAOX2) and proteins of the protein quality control system, i.e. chaperones (HSP70 and DnaJ co-chaperones), proteases and proteasomal proteins (regulatory subunits of the 26S proteasome; Rpn1/2). The immunofluorescence analysis revealed mislocalization of many PTS1-proteins (DAAO, CAT, MFE2, ACOX1, EHHADH) in rat renal sections, strongly suggesting that propiverine primarily binds to PTS1 proteins resulting in the formation of PTS1 but not PTS2 or peroxisomal membrane protein (PMP) accumulations. Moreover, chaperones involved in peroxisomal trafficking (HSC70, DnaJB1) and peroxisomal biogenesis factor proteins (PEX3, PEX5, PEX7), also presented with distinct mislocalization patterns. Concomitantly, an increased number of peroxisomes was observed, suggestive of a compensatory mechanism for the presumably suboptimally functioning peroxisomes. Overall, the data presented suggested that propiverine interacts exclusively with DAAO or with a selected number of PTS1 proteins. The consequence of this interaction is the abrogated trafficking and peroxisomal import of PTS1 proteins concomitant with their nuclear and cytosolic accumulation due to inhibited degradation and imbalanced protein homeostasis.

Assessment of inhibitory effects on major human cytochrome P450 enzymes by spasmolytics used in the treatment of overactive bladder syndrome

BACKGROUND

The objective of this study was to examine the inhibitory potential of darifenacin, fesoterodine, oxybutynin, propiverine, solifenacin, tolterodine and trospium chloride on the seven major human cytochrome P450 enzymes (CYP) by using a standardized and validated seven-in-one cytochrome P450 cocktail inhibition assay.

METHODS

An in vitro cocktail of seven highly selective probe substrates was incubated with human liver microsomes and varying concentrations of the seven test compounds. The major metabolites of the probe substrates were simultaneously analysed using a validated liquid chromatography tandem mass spectrometry (LC-MS/MS) method. Enzyme kinetics were estimated by determining IC50 and Ki values via nonlinear regression. Obtained Ki values were used for predictions of potential clinical impact of the inhibition using a static mechanistic prediction model.

RESULTS

In this study, 49 IC50 experiments were conducted. In six cases, IC50 values lower than the calculated threshold for drug-drug interactions (DDIs) in the gut wall were observed. In these cases, no increase in inhibition was determined after a 30 min preincubation. Considering a typical dosing regimen and applying the obtained Ki values of 0.72 µM (darifenacin, 15 mg daily) and 7.2 µM [propiverine, 30 mg daily, immediate release (IR)] for the inhibition of CYP2D6 yielded a predicted 1.9-fold and 1.4-fold increase in the area under the curve (AUC) of debrisoquine (CYP2D6 substrate), respectively. Due to the inhibition of the particular intestinal CYP3A4, the obtained Ki values of 14 µM of propiverine (30 mg daily, IR) resulted in a predicted doubling of the AUC for midazolam (CYP3A4 substrate).

CONCLUSIONS

In vitro/in vivo extrapolation based on pharmacokinetic data and the conducted screening experiments yielded similar effects of darifenacin on CYP2D6 and propiverine on CYP3A4 as obtained in separately conducted in vivo DDI studies. As a novel finding, propiverine was identified to potentially inhibit CYP2D6 at clinically occurring concentrations.

Results of a randomized, double-blind, active-controlled clinical trial with propiverine extended release 30 mg in patients with overactive bladder

OBJECTIVE

To compare the efficacy and safety of the 30 mg extended release (ER) formulation of propiverine hydrochloride with the 4 mg ER formulation of tolterodine tartrate in patients with overactive bladder (OAB) in a non-inferiority trial.

PATIENTS AND METHODS

Eligible patients, aged 18-75 years and with symptoms of OAB, were enrolled in this multicentre, randomized, double-blind, parallel-group, active-controlled study. After a 2-week screening period, patients were randomized at a 1:1 ratio to receive either propiverine ER 30 mg or tolterodine ER 4 mg daily during the 8-week treatment period. Efficacy was assessed using a 3-day voiding diary and patient's self-reported assessment of treatment effect. Safety assessment included recording of adverse events, laboratory test results, measurement of post-void residual urine and electrocardiograms.

RESULTS

A total of 324 patients (244 female and 80 male) were included in the study. Both active treatments improved the variables included in the voiding diary and in the patient's self-reported assessment. The change from baseline in the number of voidings per 24 h was significantly greater in the propiverine ER 30 mg group compared with the tolterodine ER 4 mg group after 8 weeks of treatment (full analysis set [FAS] -4.6 ± 4.1 vs -3.8 ± 5.1; P = 0.005). Significant improvements were also observed for the change of urgency incontinence episodes after 2 weeks (P = 0.026) and 8 weeks (P = 0.028) of treatment when comparing propiverine ER 30 mg with tolterodine ER 4 mg. Both treatments were well tolerated, with a similar frequency of adverse drug reactions in both the propiverine ER 30 mg and tolterodine ER 4 mg groups (FAS 40.7 vs 39.5%; P = 0.8). More patients treated with tolterodine ER 4 mg discontinued the treatment because of adverse drug reactions compared with propiverine ER 30 mg (7.4 vs 3.1%).

CONCLUSIONS

Propiverine ER 30 mg was confirmed to be an effective and well-tolerated treatment option for patients with OAB symptoms. This first head-to-head study showed non-inferiority of propiverine ER 30 mg compared with tolterodine ER 4 mg.

Propiverine: a review of its use in the treatment of adults and children with overactive bladder associated with idiopathic or neurogenic detrusor overactivity, and in men with lower urinary tract symptoms

Propiverine is a well established antimuscarinic agent with a mixed mode of action in the treatment of symptoms associated with overactive bladder (OAB). As well as blocking muscarinic receptors in the detrusor muscle, the drug also inhibits cellular calcium influx, thereby diminishing muscle spasm. In patients with symptoms of OAB resulting from idiopathic detrusor overactivity (IDO) or neurogenic detrusor overactivity (NDO), propiverine demonstrated dose-dependent efficacy and tolerability, with adverse events consistent with those associated with all antimuscarinic agents. In adults with IDO, propiverine demonstrated similar efficacy to that of other antimuscarinic agents (including solifenacin, tolterodine, oxybutynin and imidafenacin) and, in adults with NDO, propiverine and oxybutynin demonstrated similar efficacy. Propiverine was generally well tolerated in these patient populations, with a lower incidence of dry mouth than that associated with oxybutynin. In men with lower urinary tract symptoms (LUTS), and in whom the presence of benign prostatic enlargement (BPE) was implicated, propiverine administered as add-on therapy to an α(1)-adrenoceptor antagonist demonstrated similar or superior efficacy to that achieved with an α(1)-adrenoceptor antagonist alone, and combination therapy was particularly effective in patients with urinary storage symptoms. Combination therapy was generally well tolerated, but was associated with a higher incidence of adverse events than an α(1)-adrenoceptor antagonist alone. In children and adolescents with IDO/OAB or NDO, propiverine was generally more effective and better tolerated than oxybutynin. In conclusion, propiverine provides a valuable option for the treatment of adults and children with OAB associated with IDO or NDO, and in men with storage LUTS.

Pharmacokinetics and toxicity of antimuscarinic drugs for overactive bladder treatment in females

INTRODUCTION

Antimuscarinics (AMs) are the mainstay of pharmacological treatment of overactive bladder (OAB), a symptom complex defined by the presence of urinary urgency, usually associated with frequency and nocturia, with or without urgency urinary incontinence. The AMs used to treat OAB differ in their pharmacological profiles, which may affect their potential for causing adverse effects (AEs).

AREAS COVERED

The present article aims to review the literature about pharmacokinetics (PK) of the different AMs used in the treatment of OAB. Furthermore, the AEs related to the use of these drugs and their incidence are presented. This systematic review is based on material searched and obtained via Medline, Pubmed and EMBASE up to March 2012 using the search terms "adverse events, pharmacokinetics, tolerability" in combination with "darifenacin, fesoterodine, imidafenacin, oxybutynin, propiverine, solifenacin, tolterodine, and trospium."

EXPERT OPINION

Antimuscarinics are the first-line pharmacological treatment for OAB. Despite the development of new molecules that improve their efficacy/safety profile, there are some drugs that are pharmacokinetically more appropriate to be prescribed in specific populations such as patients with neurological disease or the elderly. Moreover, research should be encouraged in evaluating antimuscarinics in conjunction with other drugs such as estrogens or beta-agonists. The identification of prognostic criteria for pharmacological therapy would be helpful.

Propiverine-induced accumulation of nuclear and cytosolic protein in F344 rat kidneys: isolation and identification of the accumulating protein

Male and female F344 rats but not B6C3F1 mice exposed for 104 weeks to propiverine hydrochloride (1-methylpiperid-4-yl 2,2-diphenyl-2-(1-propoxy)acetate hydrochloride), used for treatment of patients with neurogenic detrusor overactivity (NDO) and overactive bladder (OAB), presented with an accumulation of proteins in the cytosol and nuclei of renal proximal tubule epithelial cells, yet despite this, no increased renal tumor incidence was observed. In order to provide an improved interpretation of these findings and a better basis for human health risk assessment, male and female F344 rats were exposed for 16 weeks to 1000 ppm propiverine in the diet, the accumulating protein was isolated from the kidneys via cytosolic and nuclear preparations or laser-capture microdissection and analyzed using molecular weight determination and mass spectrometry. The accumulating protein was found to be d-amino acid oxidase (DAAO), an enzyme involved in amino and fatty acid metabolism. Subsequent reanalysis of kidney homogenate and nuclear samples as well as tissue sections using western blot and DAAO-immunohistochemistry, confirmed the presence and localization of DAAO in propiverine-treated male and female F344 rats. The accumulation of DAAO only in rats, and the limited similarity of rat DAAO with other species, including humans, suggests a rat-specific mechanism underlying the drug-induced renal DAAO accumulation with little relevance for patients chronically treated with propiverine.