Quality by Design (QbD) Approach for a Nanoparticulate Imiquimod Formulation as an Investigational Medicinal Product.

The present article exemplifies the application of the concept of quality by design (QbD) for the systematic development of a nanoparticulate imiquimod (IMQ) emulsion gel formulation as an investigational medicinal product (IMP) for evaluation in an academic phase-I/II clinical trial for the treatment of actinic keratosis (AK) against the comparator Aldara (EudraCT: 2015-002203-28). The design of the QbD elements of a quality target product profile (QTPP) enables the identification of the critical quality attributes (CQAs) of the drug product as the content of IMQ, the particle-size distribution, the pH, the rheological properties, the permeation rate and the chemical, physical and microbiological stability. Critical material attributes (CMAs) and critical process parameters (CPPs) are identified by using a risk-based approach in an Ishikawa diagram and in a risk-estimation matrix.

UHPLC Enantiomer Resolution for the ɑ/β-Adrenoceptor Antagonist -Carvedilol and Its Major Active Metabolites on Chiralpak IB N-5.

Carvedilol (CAR), a racemic lipophilic aryloxy propanolamine, acts as a selective α-adrenoreceptor antagonist and a nonselective β-adrenoreceptor antagonist. CAR metabolism mainly produces three active metabolites: desmethyl carvedilol (DMC), 4'-hydroxy carvedilol (4'OHC) and 5'-hydroxy carvedilol (5'OHC). The oxidative -(-)-metabolites contribute to the β-antagonistic effect, yet not to the α-antagonistic effect to be observed after drug dosage.

Therapy-relevant aberrant expression of MRP3 and BCRP mRNA in TCC-/SCC-bladder cancer tissue of untreated patients.

Multidrug resistance (MDR) is a critical factor, which results in suboptimal outcomes in cancer chemotherapy. One principal mechanism of MDR is the increased expression of ATP-binding cassette (ABC) transporters. Of these, multidrug resistance-associated protein 3 (MRP3) and breast cancer resistance protein (BCRP) confer MDR when overexpressed in cancer cell lines.

Circadian variations in exsorptive transport: in situ intestinal perfusion data and in vivo relevance.

The circadian timing system (CTS) governs the 24-h rhythm of the organism and, hence, also main pathways responsible for drug pharmacokinetics. P-glycoprotein (P-gp) is a drug transporter that plays a pivotal role in drug absorption, distribution, and elimination, and temporal changes in its activity may affect input, output, activity, and toxicity profile of drugs. In the current study, the influence of different circadian stages on the overall intestinal permeability (P(eff)) of the P-gp substrates talinolol and losartan was evaluated in in situ intestinal perfusion studies in rats.

Baclofen ester and carbamate prodrug candidates: a simultaneous chromatographic assay, resolution optimized with DryLab.

Baclofen exhibits insufficient CNS-availability when dosed systemically. Hence, prodrug candidates (methyl, ethyl, 1-propyl, 2-propyl and butyl 4-(tert-butoxycarbonyl amino)-3-(4-chlorophenyl) butanoate) were synthesized aiming at CNS-levels appropriate for the treatment of spastic disorders. The characterization of some biopharmaceutically highly relevant physicochemical properties (LogP and aqueous solubility) and the evaluation of biophase levels represent one important component of the project.

Expression of RFC/SLC19A1 is associated with tumor type in bladder cancer patients.

Urinary bladder cancer (UBC) ranks ninth in worldwide cancer. In Egypt, the pattern of bladder cancer is unique in that both the transitional and squamous cell types prevail. Despite much research on the topic, it is still difficult to predict tumor progression, optimal therapy and clinical outcome.

Species difference in the effect of grapefruit juice on intestinal absorption of talinolol between human and rat.

Bioavailability of talinolol, a beta(1)-adrenergic receptor antagonist, was enhanced by coadministration with grapefruit juice (GFJ) in rats, whereas GFJ ingestion markedly reduced the absorption of talinolol in humans. Because our recent study indicated that the inhibitory effect of GFJ on organic anion-transporting polypeptide (Oatp)- and P-gp-mediated talinolol absorption depends on the concentration of naringin in ingested GFJ, the apparent inconsistent findings may be explained by the species difference in the affinity of naringin for OATP/Oatp and P-gp multidrug resistance 1 (MDR1/Mdr1) between humans and rats. Although human MDR1-mediated talinolol transport was not inhibited by 2000 microM naringin, naringin inhibited human OATP1A2-, rat Oatp1a5-, and rat Mdr1a-mediated talinolol transport with IC(50) values of 343, 12.

Concentration-dependent effect of naringin on intestinal absorption of beta(1)-adrenoceptor antagonist talinolol mediated by p-glycoprotein and organic anion transporting polypeptide (Oatp).

Purpose: The purpose of this study is to clarify the impact of P-gp and Oatp on intestinal absorption of the beta(1)-adrenoceptor antagonist talinolol.

Methods: P-gp-mediated transport was measured in LLC-PK1/MDR1 cells. Oatp-mediated uptake was evaluated with Xenopus oocytes expressing Oatp1a5.

Influence of green and black tea on folic acid pharmacokinetics in healthy volunteers: potential risk of diminished folic acid bioavailability.

Previous in vitro studies using Caco-2 cell monolayers suggested a possible interaction between green and black tea and folic acid at the level of intestinal absorption. The main purpose of the present study was to investigate a possible pharmacokinetic interaction between tea and folic acid in healthy volunteers. In an open-labeled randomized cross-over study, the pharmacokinetic interaction between tea and folic acid (0.

Pharmacokinetic evaluation of oral fenofibrate nanosuspensions and SLN in comparison to conventional suspensions of micronized drug.

An increasing number of newly developed drugs show bioavailability problems due to poor water solubility. Formulating the drugs as nanosuspensions may help to overcome these problems by increasing saturation solubility and dissolution velocity. In the present study the bioavailability of the poorly soluble fenofibrate following oral administration was investigated in rats.

Inhibition of folic acid uptake by catechins and tea extracts in Caco-2 cells.

In this present study it was aimed to determine whether the catechins contained in green tea and the whole extracts of Camellia sinensis (Theaceae) inhibit the uptake of folic acid by Caco-2 cell monolayers. Our results indicate that (-)-epigallocatechin 3-gallate (EGCG) and (-)-epicatechin 3-gallate (ECG) inhibit cellular folic acid uptake with IC50 values of 34.8 micromol/L and 30.

Bidirectional membrane transport: simulations of transport inhibition in uptake studies explain data obtained with flavonoids.

The purpose of the simulations was to obtain an estimate of concentration-dependent uptake curves when two counteracting transporters are present. On the basis of this experimental data obtained with a pair of ovarian carcinoma cell lines, one of which was not expressing the exsorptive transporter P-glycoprotein and one of which was an MDR1-transfected, P-glycoprotein expressing variant, the kinetics of cellular uptake of the radiolabel (3)H-talinolol were calculated and the inhibitory constants at P-gp were determined for different flavonoids. With respect to the inhibition of P-gp function, among others, naringenin and isoquercitrin were identified as inhibitors, yet estimation of the inhibitory constant was only possible for uptake values corrected for non-P-glycoprotein-mediated processes.

In silico modeling of non-linear drug absorption for the P-gp substrate talinolol and of consequences for the resulting pharmacodynamic effect.

Purpose: The aim of the present work was to demonstrate P-glycoprotein's involvement in the non-linear talinolol pharmacokinetics using an advanced compartment and transit model (ACAT) and to compare the results predicted from the model to the finding of a phase I dose escalation study with oral talinolol doses increasing from 25 to 400 mg.

Materials And Methods: Besides minimum input parameters for the compound (pKa(s), solubility at one or more pH's, Peff, doses, formulation, diffusivity), physiological and pharmacokinetic properties, transporter data are included in these predictions. The simulations assumed higher expression levels in lower gastrointestinal regions, in particular in the colon, which is in accordance with the results of intestinal rat perfusion studies and intestinal distribution data from rats, catfishes, micropigs and humans reported in the literature.

Effects of controlled-release on the pharmacokinetics and absorption characteristics of a compound undergoing intestinal efflux in humans.

Objective: The number of active pharmaceutical ingredients (API) undergoing inhibitable and saturable intestinal efflux is considerable. As a consequence, absorption and bioavailability may depend on the intestinal concentration profile of the drug and may vary as a function of dose and release rate of the drug from the dosage form. The impact of controlled versus immediate-release on the absorption of P-glycoprotein substrates is currently unknown.

In vivo non-linear intestinal permeability of celiprolol and propranolol in conscious dogs: evidence for intestinal secretion.

The objective of this study was to investigate the absorption mechanism of celiprolol as a potential source of the drug's non-linear oral pharmacokinetics by determining its intestinal permeability as a function of concentration in vivo in dogs. Solutions of different celiprolol concentrations containing propranolol as an internal absorption marker were perfused through an isolated jejunal segment and samples were analyzed by an enantioselective HPLC method (Hartmann et al., J.

Rate-limiting biotransformation of triamterene is mediated by CYP1A2.

Objective: Triamterene (TA), a potassium-sparing diuretic, is extensively metabolized by hydroxylation in 4'-position and subsequent conjugation by cytosolic sulfotransferases. To identify the cytochrome P450 enzyme(s) catalyzing hydroxylation of triamterene (the rate-limiting step in the formation of the sulfate ester (STA)), in vitro incubation studies were performed with human liver microsomes.

Methods: Initial rates of TA hydroxylation (0 - 300 microM) were determined during a ten-minute-incubation period with liver microsomes of two donors.

Modulation of drug transport by selected flavonoids: Involvement of P-gp and OCT?

Flavonoids, as a common component of daily nutrition, are a possible source of interference with absorption processes, due to modulation of transporting proteins. In this study, the influence of selected flavonoids (quercetin, isoquercitrin, spiraeoside, rutin, kaempferol, naringenin, naringin, and kaempferol) on the transport of the P-gp substrate [3H]talinolol across Caco-2 cell monolayers was investigated. To elucidate the mechanism behind the interaction observed in this system the potency of the flavonoids to replace [3H]talinolol from its P-gp binding site as well as their activity to inhibit OCT2-mediated [14C]TEA uptake into LLC-PK(1) cells were measured, as P-gp and OCT have been shown to be present in Caco-2 cells.

Nanosuspension formulations for low-soluble drugs: pharmacokinetic evaluation using spironolactone as model compound.

Various particle sizes of spironolactone as a model low solubility drug were formulated to yield micro-and nanosuspensions of the type solid lipid nanoparticles and DissoCubes. Seven oral and one i.v.

Selective downregulation of the MDR1 gene product in Caco-2 cells by stable transfection to prove its relevance in secretory drug transport.

Considerable interest is focused on overcoming multidrug resistance (MDR) in cancer chemotherapy. The in vitro experiments to characterize P-glycoprotein's (P-gp) function and to decrease its effects have led to a variety of strategies such as addition of competitors or supplementation of the medium with oligonucleotides complementary to the 5'-end of the MDR1-mRNA. For the Caco-2 cell line, an in vitro model for absorption screening, expressing multiple transporters including P-gp, which pumps substances back into the apical solution, P-gp activity might mask other relevant transport proteins' activity.

Identification of P-glycoprotein substrates and inhibitors among psychoactive compounds--implications for pharmacokinetics of selected substrates.

The pharmacokinetics of antipsychotic drugs has become an integral part in understanding their pharmacodynamic activity and clinical effects. In addition to metabolism aspects, carrier-mediated transport, particularly secretion by ABC transporters, has been discussed as potentially relevant for this group of therapeutics. In this study, the psychoactive compounds perphenazine, flupentixol, domperidone, desmethyl clozapine, haloperidol, fluphenazine, fluvoxamine, olanzapine, levomepromazine, perazine, desmethyl perazine, clozapine, quetiapine and amisulpride were characterized in terms of P-glycoprotein (P-gp) affinity and transport.

Lipophilicities of baclofen ester prodrugs correlate with affinities to the ATP-dependent efflux pump P-glycoprotein: relevance for their permeation across the blood-brain barrier?

Purpose: Distribution to the effect site is a prerequisite for the therapeutic effect and determined by physicochemical properties and affinities to inside- and outside-directed membrane transporters. Based on the hypothesis that lipophilic esters of the GABA-derivative baclofen have a higher affinity to brain tissue, baclofen esters (methyl, ethyl, 1-propyl, 2-propyl, butyl) were studied regarding their penetration through the blood-brain barrier and their affinities to P-glycoprotein (P-gp).

Methods: Octanol-water distribution coefficients (D) served as lipophilicity parameters.

Determination of triamterene and its main metabolite hydroxytriamterene sulfate in human urine by capillary electrophoresis using ultraviolet absorbance and laser-induced fluorescence detection.

Two capillary electrophoresis methods have been developed for the direct determination of triamterene and its main metabolite hydroxytriamterene sulfate in human urine. Analytes were detected using conventional UV detection as well as laser-induced fluorescence (LIF) detection with an HeCd-laser operating at a wavelength of 325 nm. The results of both detection techniques were compared.

Intestinal drug efflux: formulation and food effects.

The intestine, primarily regarded as an absorptive organ, is also prepared for the elimination of certain organic acids, bases and neutral compounds depending on their affinity to intestinal carrier systems. Several of the transport systems known to mediate efflux in the major clearing organs--liver and kidney--are also expressed in the intestine. Examples of secretory transporters in the intestine are P-glycoprotein, members of the multidrug resistance associated protein family, breast cancer resistance protein, organic cation transporters and members of the organic anion polypeptide family.

The influence of age on the pharmacokinetics and pharmacodynamics of bemetizide and triamterene: a single and multiple dose study.

Diuretics are a frequent cause of adverse drug effects in the elderly, many times involving drug-drug interactions. In addition, multiple chronic diseases, age-dependent pharmacokinetic and pharmacodynamic changes, and a decreased homeostatic capacity often complicate diuretic therapy in the elderly. The pharmacokinetics (area under the plasma concentration-time curve: AUC; peak concentration in plasma: c(max); time to reach peak concentration: t(max); terminal half-life: t(1/2)) and pharmacodynamics (urine flow rates and renal excretion rates of Na(+) at 1, 3, and 6 h after oral administration) of a fixed combination of 25 mg bemetizide and 50 mg triamterene were investigated in 15 elderly patients (age 70-84 years) and 10 young volunteers (age 18-30 years) after a single dose (day 1) and after multiple doses (at steady state, day 8).

Screening of beta-2 agonists and confirmation of fenoterol, orciprenaline, reproterol and terbutaline with gas chromatography-mass spectrometry as tetrahydroisoquinoline derivatives.

A new method for a comprehensive screening and confirmation of beta-2 agonists in human urine is presented based on gas chromatography-low-resolution mass spectrometry (GC-MS) using electron impact ionisation (EI). After hydrolysis of the conjugates with beta-glucuronidase/arylsulfatase a derivatisation step with formaldehyde converts fenoterol, orciprenaline, reproterol and terbutaline to one derivative, a tetrahydroisoquinoline, while the other beta-2 agonists remain unchanged. Liquid-liquid extraction and trimethylsilylation follow.