Mitochondrial-Targeted CS@KET/P780 Nanoplatform for Site-Specific Delivery and High-Efficiency Cancer Immunotherapy in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a form of malignancy with limited curative options available. To improve therapeutic outcomes, it is imperative to develop novel, potent therapeutic modalities. Ketoconazole (KET) has shown excellent therapeutic efficacy against HCC by eliciting apoptosis. However, its limited water solubility hampers its application in clinical treatment. Herein, a mitochondria-targeted chemo-photodynamic nanoplatform, CS@KET/P780 NPs, is designed using a nanoprecipitation strategy by integrating a newly synthesized mitochondria-targeted photosensitizer (P780) and chemotherapeutic agent KET coated with chondroitin sulfate (CS) to amplify HCC therapy. In this nanoplatform, CS confers tumor-targeted and subsequently pH-responsive drug delivery behavior by binding to glycoprotein CD44, leading to the release of P780 and KET. Mechanistically, following laser irradiation, P780 targets and destroys mitochondrial integrity, thus inducing apoptosis through the enhancement of reactive oxygen species (ROS) buildup. Meanwhile, KET-induced apoptosis synergistically enhances the anticancer effect of P780. In addition, tumor cells undergoing apoptosis can trigger immunogenic cell death (ICD) and a longer-term antitumor response by releasing tumor-associated antigens (TAAs) and damage-associated molecular patterns (DAMPs), which together contribute to improved therapeutic outcomes in HCC. Taken together, CS@KET/P780 NPs improve the bioavailability of KET and exhibit excellent therapeutic efficacy against HCC by exerting chemophototherapy and antitumor immunity.

Comparison of two different multiple dual-mode counter-current chromatograph for separation of ketoconazole enantiomers

In this work, two different multiple dual-mode (MDM) counter-current chromatography methods, conventional MDM and modified MDM elution modes, were compared for the chiral separation of the ketoconazole enantiomers. The biphasic solvent system which consisted of n-hexane: isobutyl acetate: 0.1 mol/L phosphate buffer (2:4:6, v/v) (pH = 8.5) was employed as stationary phase and mobile phase. And the hydroxypropyl-β-cyclodextrin (HP-β-CD) with a concentration of 100 mmol/L was dissolved in the phosphate buffer, as the chiral selector. Under two different methods, dual-mode (DM) elution was performed to determine the time of the transformed phase roles and multiple cycles were performed to isolate ketoconazole, respectively. The result indicated that the modified MDM elution had a significant improvement on the separation, increasing the resolution from 0.51 to 1.19, while the resolution was increased from 0.40 to 0.79 by the conventional MDM elution. Ultimately, baseline separation of ketoconazole enantiomers was essentially achieved by high-speed counter-current chromatography under optimized modified MDM separation conditions. The final recoveries of the two enantiomers, R-(K) and S-(K), were 92.5 % and 83.3 %, respectively, corresponding to enantiomeric excess values of 99.0 % and 97.0 %, as determined by HPLC.

Traditional Herb (Moxa) Modified Zinc Oxide Nanosheets for Quick, Efficient and High Tissue Penetration Therapy of Fungal Infection

Fungal infection possesses the characteristics of high invasion depth and easy formation of a biofilm under the skin, which greatly hinders the treatment process. Here, traditional Chinese medicine moxa is carbonized and modified with zinc oxide (ZnO) nanosheets to synthesize carbonized moxa@ZnO (CMZ) with the dual response properties of yellow light (YL) and ultrasound (US) for synergistic antifungal therapy. CMZ with narrow bandgap can respond to long-wavelength YL that is highly safe and helpful for skin repair. Simultaneously, CMZ with a piezoelectric effect can further enhance the photocatalytic efficiency under the stimulation of US with high tissue penetration. Gene mechanism investigation indicates that when exposed to US and YL irradiation, CMZ-based therapy can adjust the expression of genes associated with fungal virulence, metabolic activity, mycelial growth and biofilm development, thus efficaciously eradicating planktonic Candida albicans (C. albicans) and mature biofilm. Importantly, despite the 1.00 cm thick tissue barrier, CMZ can rapidly eliminate 99.9% of C. albicans within 4 min, showing a satisfactory deep fungicidal efficacy. The in vivo therapeutic effect of this strategy is demonstrated in both open wound and deep cutaneous infection tests, speaking of dramatically better efficacy than the traditional fungicide ketoconazole (KTZ).

Novel anti-dandruff shampoo incorporated with ketoconazole-coated zinc oxide nanoparticles using green tea extract

BACKGROUND

Dandruff caused by Malassezia furfur is a prevailing fungal infection. Although ketoconazole (KTZ) is widely intended for anti-dandruff treatment, poor solubility, and epidermal permeability limits its use and the marketed KTZ shampoo adversely effects scalp and hair.

OBJECTIVE

To prepare a novel shampoo loaded with KTZ-coated zinc oxide nanoparticles using green tea extract and evaluate its antifungal activity.

METHODS

The KTZ-coated zinc oxide nanoparticles was prepared by green synthesis and was characterized by UV, FTIR, XRD, and the drug entrapment efficiency was investigated. The antifungal activity of the nanoparticles with respect to standard drug, KTZ was tested against Malassezia furfur. Further, a novel antidandruff shampoo was developed by incorporating the prepared nanoparticles into the shampoo base.

RESULTS

The formation of KTZ-coated ZnO nanoparticles was confirmed by UV and FTIR analysis. XRD analysis confirmed the amorphous phase of KTZ in nanoparticles. The drug entrapment efficiency was found to be 91.84%. The prepared nanoparticles showed enhanced activity against Malassezia furfur compared to drug of choice, KTZ (1%). The evaluation of shampoo showed an ideal result.

CONCLUSION

KTZ-coated ZnO nanoparticles loaded novel shampoo in comparison to marketed anti-dandruff shampoo could be an effective alternate for the treatment of dandruff.

Potential interactions between triazole antifungal agents and lorlatinib based on ultra-performance liquid chromatography-tandem mass spectrometry in rat plasma

AIM

Our study is to investigate the effects of triazole antifungal drugs on the pharmacokinetics of lorlatinib in rats.

METHODS

The samples were precipitated with methanol. Chromatographic separation was performed on a ultra-performance liquid chromatography (UPLC) system using a BEH C18 column. The mobile phase consisted of 0.1% formic acid water and methanol. Lorlatinib and crizotinib (internal standard) were detected in multiple reaction monitoring mode. The fragment ions were 407.3-228.07 for lorlatinib and m/z 450.3-260.0 for crizotinib. Lorlatinib and different triazole antifungal drugs were given to Sprague Dawley rats by gavage, and blood was collected from the tail vein at a certain time point. The validated UPLC-MS/MS method was applied to a drug interaction study of ketoconazole, voriconazole, itraconazole, and posaconazole with lorlatinib in rats.

RESULTS

Ketoconazole and voriconazole significantly inhibited lorlatinib metabolism. When administration with ketoconazole and voriconazole, the area under the curve from time zero to infinity of lorlatinib increased by 49.0% and 104.3%, respectively; the clearance decreased by 40.0% and 40.0%, respectively. While itraconazole and posaconazole did not affect lorlatinib pharmacokinetics.

CONCLUSION

The UPLC-MS/MS-based assay is helpful to further understand the pharmacokinetics of lorlatinib in rats, and confirmed the findings that the combination of lorlatinib with CYP3A inhibitors should be avoided as predicted by our pre-clinical studies.

Analysis of stabilization mechanisms in β-lactoglobulin-based amorphous solid dispersions by experimental and computational approaches

Our previous work shows that β-lactoglobulin-stabilized amorphous solid dispersion (ASD) loaded with 70 % indomethacin remains stable for more than 12 months. The stability is probably due to hydrogen bond networks spread throughout the ASD, facilitated by the indomethacin which has both hydrogen donors and acceptors. To investigate the stabilization mechanisms further, here we tested five other drug molecules, including two without any hydrogen bond donors. A combination of experimental techniques (differential scanning calorimetry, X-ray power diffraction) and molecular dynamics simulations was used to find the maximum drug loadings for ASDs with furosemide, griseofulvin, ibuprofen, ketoconazole and rifaximin. This approach revealed the underlying stabilization factors and the capacity of computer simulations to predict ASD stability. We searched the ASD models for crystalline patterns, and analyzed diffusivity of the drug molecules and hydrogen bond formation. ASDs loaded with rifaximin and ketoconazole remained stable for at least 12 months, even at 90 % drug loading, whereas stable drug loadings for furosemide, griseofulvin and ibuprofen were at a maximum of 70, 50 and 40 %, respectively. Steric confinement and hydrogen bonding to the proteins were the most important stabilization mechanisms at low drug loadings (≤ 40 %). Inter-drug hydrogen bond networks (including those with induced donors), ionic interactions, and a high Tg of the drug molecule were additional factors stabilizing the ASDs at drug loading greater than 40 %.

An integrated One Health framework for holistic evaluation of risks from antifungal agents in a large-scale multi-city study

A new framework for retrospective mass spectral data mining for antifungal agents (AFs) and Wastewater-Based Epidemiology (WBE) was developed as part of One Health framework to tackle risks from AFs. A large scale, multi-city study was undertaken in South-West England. Key drivers of AFs in the catchment were identified with communal wastewater discharges being the main driver for human AFs (fluconazole, ketoconazole) and agricultural runoff being the main driver for pesticide AFs (prochloraz, prothioconazole and tebuconazole). Average WBE-estimated human used fluconazole and ketoconazole PNDIs (population normalised daily intake) exceeded 300 mg day-1 1000 inh-1 and 2000 mg day-1 1000 inh-1. This is much higher than PNDPs (population normalised daily prescriptions <40 mg day-1 1000 inh-1 and <80 mg day-1 1000 inh-1 for fluconazole and ketoconazole respectively). This was expected due to both prescription and over-the-counter usage, and both oral and topical applications. Pesticide AF, prothioconazole had PNDIs <40,000 mg day-1 1000 inh -1, which gave intake: 0.43, 0.26, 0.07 mg kg-1 in City A, B, and C, likely due to accounting for external/non-human sources. This is higher than the acceptable daily intake (ADI) of 0.01 mg kg-1bw day-1, which warrants further study. Intake per kg of body weight estimated using tebuconazole was 0.86, 1.39, 0.12, 0.13, and 2.7 mg kg-1 in City A-E respectively and is likely due to external/non-human sources. Intake calculated using its metabolite was 0.02 and 0.01 mg kg-1 in City B and C respectively, which aligned with ADI (0.03 mg kg-1bw day-1). The environmental risk assessment of AFs indicated low/medium risk from fluconazole, prochloraz, and tebuconazole, medium risk from epoxiconazole, prothioconazole's metabolite, and tebuconazole, and high risk for prothioconazole in river water. High risk was estimated from fluconazole, epoxiconazole, prothioconazole and its metabolite, tebuconazole, ketoconazole in wastewater samples, which is important during raw sewage discharge events via sewer overflows.

CYP11A1 silencing suppresses HMGCR expression via cholesterol accumulation and sensitizes CRPC cell line DU-145 to atorvastatin

Statins, which are cholesterol synthesis inhibitors, are well-known therapeutics for dyslipidemia; however, some studies have anticipated their use as anticancer agents. However, epithelial cancer cells show strong resistance to statins through an increased expression of HMG-CoA reductase (HMGCR), an inhibitory target of statins. Castration-resistant prostate cancer (CRPC) cells synthesize androgens from cholesterol on their own. We performed suppression of CYP11A1, a rate-limiting enzyme in androgen synthesis from cholesterol, using siRNA or inhibitors, to examine the effect of steroidogenesis inhibition on statin sensitivity in CRPC cells. Here, we suggested that CYP11A1 silencing sensitized the statin-resistant CRPC cell line DU-145 to atorvastatin via HMGCR downregulation by an increase in intracellular free cholesterol. We further demonstrated that CYP11A1 silencing induced epithelial-mesenchymal transition, which converted DU-145 cells into a statin-sensitive phenotype. This suggests that concomitant use of CYP11A1 inhibitors could be an effective approach for overcoming statin resistance in CRPC. Moreover, we showed that ketoconazole, a CYP11A1 inhibitor, sensitized DU-145 cells to atorvastatin, although not all the molecular events observed in CYP11A1 silencing were reproducible. Although further studies are necessary to clarify the detailed mechanisms, ketoconazole may be effective as a concomitant drug that potentiates the anticancer effect of atorvastatin.

Synthesis, crystal structure and molecular docking study of novel isoxazole derivatives as CYP450 inhibitors in search of anticancer agents

Synthesis of some novel isoxazole derivatives and their molecular docking with enzymes from CYP450 family carried out using erlotinib, gemcitabine and ketoconazole as reference drugs are reported in this work. Eight isoxazole derivatives of 3,4-substituted phenyl 3-chloroacrylaldehyde and one isoxazole derivative of cinnamaldehyde were synthesized. A molecular docking study of all nine compounds shows good docking score compared to standard drugs erlotinib, gemcitabine and ketoconazole. 4-OH and 4-F derivatives were found to have strong affinity for all six CYP450 proteins under study in the present work. 4-F and 3-NO2 derivatives could be a suitable lead compound inhibitor to CYP1A2 followed by 4-OH derivatives. 4-OH derivative with significant binding affinity showed encouraging inhibition of CYP1A2, CYP2C9, CYP2C8, CYP2C19 and CYP2D6. The current predictions over these nine isoxazole derivatives of 3,4-substituted phenyl 3-chloroacrylaldehyde will be needed to be further investigated in vivo and in vitro conditions to identify the optimum therapeutic efficacy. Synthesis of the isoxazole derivatives is the first known report of the Knoevenagal condensation of acrylaldehyde derivatives to form isoxazole derivatives as per the literature survey. A detailed crystal structure study of five analogues gives insight into the solid-state structural features of this new framework with isoxazole moieties.Communicated by Ramaswamy H. Sarma.

Comparative Drug Solubility Studies Using Shake-Flask Versus a Laser-Based Robotic Method

Drug solubility is of central importance to the pharmaceutical sciences, but reported values often show discrepancies. Various factors have been discussed in the literature to account for such differences, but the influence of manual testing in comparison to a robotic system has not been studied adequately before. In this study, four expert researchers were asked to measure the solubility of four drugs with various solubility behaviors (i.e., paracetamol, mesalazine, lamotrigine, and ketoconazole) in the same laboratory with the same instruments, method, and material sources and repeated their measurements after a time interval. In addition, the same solubility data were determined using an automated laser-based setup. The results suggest that manual testing leads to a handling influence on measured solubility values, and the results were discussed in more detail as compared to the automated laser-based system. Within the framework of unavoidable uncertainties of solubility testing, it is a possibility to combine minimal experimental testing that is preferably automated with mathematical modeling. That is a practical suggestion to support future pharmaceutical development in a more efficient way.

Allosteric modulation of cytochrome P450 enzymes by the NADPH cytochrome P450 reductase FMN-containing domain

NADPH-cytochrome P450 reductase delivers electrons required by heme oxygenase, squalene monooxygenase, fatty acid desaturase, and 48 human cytochrome P450 enzymes. While conformational changes supporting reductase intramolecular electron transfer are well defined, intermolecular interactions with these targets are poorly understood, in part because of their transient association. Herein the reductase FMN domain responsible for interacting with targets was fused to the N-terminus of three drug-metabolizing and two steroidogenic cytochrome P450 enzymes to increase the probability of interaction. These artificial fusion enzymes were profiled for their ability to bind their respective substrates and inhibitors and to perform catalysis supported by cumene hydroperoxide. Comparisons with the isolated P450 enzymes revealed that even the oxidized FMN domain causes substantial and diverse effects on P450 function. The FMN domain could increase, decrease, or not affect total ligand binding and/or dissociation constants depending on both P450 enzyme and ligand. As examples, FMN domain fusion has no effect on inhibitor ketoconazole binding to CYP17A1 but substantially altered CYP21A2 binding of the same compound. FMN domain fusion to CYP21A2 resulted in differential effects dependent on whether the ligand was 17α-hydroxyprogesterone versus ketoconazole. Similar enzyme-specific effects were observed on steady-state kinetics. These observations are most consistent with FMN domain interacting with the proximal P450 surface to allosterically impact P450 ligand binding and metabolism separate from electron delivery. The variety of effects on different P450 enzymes and on the same P450 with different ligands suggests intricate and differential allosteric communication between the P450 active site and its proximal reductase-binding surface.

Silver(I) complexes containing N-heterocyclic carbene azole drugs: Synthesis, characterization, cytotoxic activity, and their BSA interactions

Cancer is one of the main public health problems globally, there is a public demand for better drugs. Rational strategies or approaches are used to improve the success of drug discovery. Our strategy was to the repurposing of well-known antifungal agents as potential anticancer drugs, such as Clotrimazole (CTZ) and Ketoconazole (KTZ). We prepared the respective iodide imidazolium salt L1: (CTZ-Me)I and L2: (KTZ-Me)I to be the intermediates toward the synthesis of its respective NHC ligand and achieve the respective silver(I)-monoNHC and silver(I)-bisNHC derivatives: [Ag(L1)I] (1), [AgI(L2)] (2) [Ag(L1)2]I. (3), [Ag(L2)2]I. (4), as well as their corresponding coordination compounds [Ag(CTZ)2]NO3 (5) and [Ag(KTZ)2]NO3 (6) where these ligands (CTZ and KTZ) coordinate to silver through the N-imidazole atom. These compounds (L1, L2 and complexes 1-6) exhibited significant activity against the tested cancer cell lines (B16-F1, murine melanoma strains and CT26WT, murine colon carcinoma). The silver(I) complexes were more active than the free ligands, complexes 2 and 4 being the most selective in B16-F1 cancer cell line. Two possibles biological targets such as DNA and albumin were examined for the observed anticancer activity. Results show that DNA is not the main target, however, the interactions with albumin suggest it can transport/delivery the metal complexes.

In Silico Screening as a Tool to Prepare Drug-Drug Cocrystals of Ibrutinib-Ketoconazole: a Strategy to Enhance Their Solubility Profiles and Oral Bioavailability

Ibrutinib (IBR) is a biopharmaceutical classification system (BCS) class II drug and an irreversible Bruton's tyrosine kinase (BTK) inhibitor. IBR has an extremely low oral bioavailability due to the activity of the CYP3A4 enzyme. The current intention of the research was to enhance solubility followed by oral bioavailability of IBR using the hot melt extrusion (HME) technique by formulating drug-drug cocrystals (DDCs). Ketoconazole (KET) is an active CYP3A4 inhibitor and was selected based on computational studies and solubility parameter prediction. Differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), proton nuclear magnetic resonance (1H NMR), and scanning electron microscopy (SEM) evaluations were employed for estimating the formation of IBR-KET DDCs. The IBR-KET DDC system was discovered to have a hydrogen bond (H-bond) and π-π-stacking interactions, in accordance with the computational results. Further, IBR-KET DDCs showed enhanced solubility, stability, powder dissolution, in vitro release, and flow properties. Furthermore, IBR-KET-DDCs were associated with enhanced cytotoxic activity in K562-CCL-243 cancer cell lines when compared with IBR and KET alone. In vivo pharmacokinetic studies have shown an enhanced oral bioavailability of up to 4.30 folds of IBR and 2.31 folds of KET through IBR-KET-DDCs compared to that of the IBR and KET suspension alone. Thus, the prepared IBR-KET-DDCs using the HME technique stand as a favorable drug delivery system that augments the solubility and oral bioavailability of IBR along with KET.

In-vitro evaluation of virulence markers and antifungal resistance of clinical Candida albicans strains isolated from Karachi, Pakistan

Candidiasis is a significant fungal infection with high mortality and morbidity rates worldwide. Candida albicans is the most dominant species responsible for causing different manifestations of candidiasis. Certain virulence traits as well as its resistance to antifungal drugs contribute to the pathogenesis of this yeast. This study was designed to determine the production of some virulence factors, such as biofilm formation and extracellular hydrolytic enzymes (esterase, coagulase, gelatinase, and catalase) by this fungus, as well as its antifungal resistance profile. A total of 304 clinical C. albicans isolates obtained from different clinical specimens were identified by a conventional diagnostic protocol. The antifungal susceptibility of C. albicans strains was determined by disk diffusion technique against commercially available antifungal disks, such as nystatin 50 μg, amphotericin B 100 unit, fluconazole 25 μg, itraconazole 10 μg, ketoconazole 10 μg, and voriconazole 1 μg. The assessment of biofilm formation was determined by the tube staining assay and spectrophotometry. Gelatinase, coagulase, catalase, and esterase enzyme production was also detected using standard techniques. A total of 66.1% (201/304) and 28.9% (88/304) of C. albicans strains were susceptible-dose dependent (SDD) to nystatin and itraconazole, respectively. Among the antifungal drugs, C. albicans strains showed high resistance to ketoconazole 24.7% (75/304); however, no statistically significant relationship between the clinical origin of C. albicans isolates and antifungal drug resistance pattern was detected. For virulence factors, the majority of the C. albicans strains actively produced biofilm and all hydrolytic enzymes. Biofilm formation was demonstrated by 88% (267/304) of the strains with a quantitative mean value 0.1762 (SD ± 0.08293). However, 100% (304/304) of isolates produced catalase enzyme, 69% (211/304) produced coagulase, 66% (197/304) produced gelatinase, and 52% (157/304) produced esterase enzyme. A significant relationship between the source of specimens and biofilm formation by C. albicans was observed; nevertheless, there was no significant relationship between different sources of C. albicans strains and the production of different enzymatic virulence factors. The study found that C. albicans strains have excellent potential to produce virulence markers and resistance to antifungals, which necessitates surveillance of these opportunistic pathogens to minimize the chances of severe invasive infections.

Rapid equilibrium dialysis, ultrafiltration or ultracentrifugation? Evaluation of methods to quantify the unbound fraction of substances in plasma

In pharmacokinetics plasma protein binding (PPB) is a well-established parameter impacting drug disposition. The unbound fraction (f_u) is arguably regarded the effective concentration at the target site. Pharmacology and toxicology, increasingly use in vitro models. The translation of in vitro concentrations to in vivo doses can be supported by toxicokinetic modelling, e.g. physiologically based toxicokinetic models (PBTK). PPB of a test substance is an input parameter for PBTK. We compared three methods to quantify f_u: rapid equilibrium dialysis (RED), ultrafiltration (UF) and ultracentrifugation (UC) using twelve substances covering a wide range of Log P_ow (-0.1 to 6.8) and molecular weights (151 and 531 g/mol): Acetaminophen, Bisphenol A, Caffeine, Colchicine, Fenarimol, Flutamide, Genistein, Ketoconazole, α-Methyltestosterone, Tamoxifen, Trenbolone and Warfarin. After RED and UF separation, three polar substances (Log P_ow < 2) were largely unbound (f_u > 70%), while more lipophilic substances were largely bound (f_u < 33%). Compared to RED or UF, UC resulted in a generally higher f_u of lipophilic substances. f_u obtained after RED and UF were more consistent with published data. For half of the substances, UC resulted in f_u higher than the reference data. UF, RED and both UF and UC, resulted in lower f_u of Flutamide, Ketoconazole and Colchicine, respectively. For f_u quantifications, the separation method should be selected according to the test substance's properties. Based on our data, RED is suitable for a broader range of substances while UC and UF are suitable for polar substances.

Inclusion complex of ketoconazole and p-sulfonic acid calix[6]arene improves antileishmanial activity and selectivity against Leishmania amazonensis and Leishmania infantum

Many previous studies presented the effectiveness of ketoconazole (KTZ) against leishmaniasis. However, the bioavailability and therapeutic efficacy of free KTZ are limited due to its low aqueous solubility. In this study, an inclusion complex (IC6HKTZ) was prepared with p-sulfonic acid calix[6]arene (CX6SO₃H) to improve the solubility and efficacy of KTZ against Leishmania amazonensis and Leishmania infantum promastigotes. A linear increase in KTZ solubility as a function of CX6SO₃H concentration was verified using the phase-solubility diagram. The resulting diagram was classified as A_L-type and a 1:1 host-guest stoichiometry was assumed to prepare IC6HKTZ by freeze-drying. FTIR, TG/DSC, XRD, and solid-state ¹³C NMR spectroscopy analyses were performed to confirm the formation of IC6HKTZ. The solubility enhancement of KTZ by 120.00 μM CX6SO₃H was about 95 times. The IC₅₀ values of IC6HKTZ and free KTZ were 3.95 and 14.35 μM for Leishmania amazonensis and 6.74 and 17.47 μM for Leishmania infantum, respectively. The viability of DH82 macrophages was not affected by CX6SO₃H. These results show that CX6SO₃H is a new supramolecular carrier system that improves antileishmanial activities to KTZ for the treatment of cutaneous and visceral leishmaniasis.

Effect of CYP3A inducer/inhibitor and licorice on hepatotoxicity and in vivo metabolism of main alkaloids of Euodiae Fructus based on UPLC-Q-Exactive-MS

ETHNOPHARMACOLOGICAL RELEVANCE

As a traditional Chinese medicine, Euodiae Fructus (EF) has been used to treat stomachache, belching, and emesis for more than a thousand years. Ancient records and modern research have shown that EF has mild toxicity, which needs to be processed with licorice juice to reduce its toxicity. Research suggested that the toxicity of EF can be caused by in vivo metabolism, but whether its metabolites are related to hepatotoxicity and whether licorice can affect the metabolism of EF have not been reported, which needed an effective strategy to clarify the correlation between metabolites and toxicity and the attenuation mechanism of licorice processing.

AIM OF THE STUDY

The poisonous substances and metabolic pathways were clarified by comparing the mechanism in vivo process of the main alkaloids of EF in normal rats and rats treated with dexamethasone (DXMS), ketoconazole (KTC), and EF processed with licorice (EFP).

MATERIALS AND METHODS

Rats were given EF and EFP by oral administration, respectively. The EF + DXMS and EF + KTC groups were pretreated with DXMS and KTC, respectively, by i. p. for seven days, and their toxicity differences were compared. The comprehensive strategy based on UPLC-Q-Exactive-MS and Orthogonal Partial Least Squares Discriminant Analysis was developed to compare the types and contents of metabolites and clarify the metabolic pathways of alkaloids among EF, EFP, EF + KTC, and EF + DXMS groups.

RESULTS

EF + DXMS group significantly increased the hepatotoxicity, whereas the EF + KTC and EFP groups reduced the hepatotoxicity compared with the EF group. One hundred and thirty-five metabolites were detected, and the metabolic pathways of the main alkaloid components related to toxicity were inferred in the plasma, urine, feces, and bile of rats. KTC and licorice similarly inhibited the production of toxic metabolites, changed metabolism in vivo, and produced many new II and a few phases I metabolites, while the contents of toxic metabolites increased in the DXMS group.

CONCLUSION

Licorice and KTC could inhibit the production of metabolites of EF related to toxicity, increase the production of other metabolites and promote the excretion of alkaloids, which may be why licorice and KTC can minimize EF toxicity.

Cytochrome P450 inhibition activities of non-standardized botanical products

ETHNOPHARMACOLOGICAL RELEVANCE

R-tab, H-tab and E-cap botanical products are used for the treatment of various ailments. R-tab is traditionally prescribed for improving urination, H-tab is for relieving piles, hemorrhoids, fissures, and rectal inflammation and E-cap is for regulating menstruation.

AIMS OF THE STUDY

To extract the botanical products and determine their potential interaction with the cytochrome P450 (CYP1A2, CYP2D6 and CYP3A4) enzymes.

MATERIALS AND METHODS

R-tab, H-tab and E-cap botanical products were first extracted using solvents and analyzed using HPLC and LC-MS/MS. The effects of methanol extracts on the cytochrome induction and inhibition activities were determined using a series of in vitro assays, including multiplex RT-qPCR, CYP activity assays (P450-Glo™) and LC-MS/MS-based assays. For the CYP induction assay, omeprazole, rifampicin and dexamethasone were used as CYP1A2, CYP2D6 and CYP3A4 inducers, respectively. Ketoconazole and acetaminophen were used as positive and negative controls for the CYP3A4 inhibition assay, whereas furafylline and ketoconazole were used as positive and negative controls for the CYP1A2 inhibition assay.

RESULTS

All three botanical products did not show any significant induction in CYP1A2, CYP2D6 and CYP3A4 mRNA expression. By contrast, R-tab inhibited the mRNA expression of CYP1A2 significantly from the lowest concentration of 0.01 μg/mL, while, H-tab inhibited the mRNA expression of CYP1A2 and CYP3A4 from 0.1 μg/mL. Based on the P450 Glo assays, E-cap extract inhibited the metabolic activity of CYP1A2 with an IC₅₀ value of 37.24 μg/mL. On the other hand, R-tab, H-tab and E-cap showed inhibitory effects on the CYP3A4 enzymatic activity with IC₅₀ values of 17.42, 18.20 and 20.60 μg/mL, respectively. However, using the LC-MS/MS-based methods, the concentration-dependent effects of R-tab and H-tab extracts on the metabolism of testosterone appeared to be more prominent, with IC₅₀ values of 51.90 and 56.90 μg/mL as compared with the rest of the results, which were all above 100 μg/mL CONCLUSION: The CYP3A4 mRNA and enzymatic activity were moderately inhibited by R-tab and H-tab. Methanol extract of botanical products in solid dosage forms can be evaluated for their herb-drug interaction risks using in vitro assays and may provide the minimum data required for safety labeling.

Caffeic and 3-(3,4-dihydroxyphenyl)glyceric acid derivatives as antimicrobial agent: biological evaluation and molecular docking studies

Herein we report the evaluation of the antimicrobial activity of some previously synthesized 3-(3,4-dihydroxyphenyl)glyceric acid in benzylated and in free 3,4 hydroxy groups in catechol moiety along with some caffeic and 3-(3,4-dihydroxyphenyl)glyceric acid amides using the microdilution method. The evaluation revealed that compounds showed in general moderate to low activity with MIC in range of 0.36-4.5 mg/mL. Compounds were also studied against three resistant bacteria strains MRSA (Methicillin-resistant Staphylococcus aureus), E. coli and P. aeruginosa. Seven out of ten compounds were more potent than reference drugs ampicillin and streptomycin against MRSA, while against another two resistant strains seven compounds showed low activity and the rest were inactive. Antifungal activity of the tested compounds was much better than antibacterial, with MIC in the range of 0.019-3.0 mg/mL. Compounds #7 and 15 showed good activity against all fungi tested, being more potent than ketoconazole and in some case even better than bifonazole used as reference drugs. Docking studies revealed that the most active compound #7 binds to the haem group of the enzyme in the same way as ketoconazole.

In vitro release, ex vivo penetration, and in vivo dermatokinetics of ketoconazole-loaded solid lipid nanoparticles for topical delivery

The study focused to evaluate and investigate optimized (using QbD) and novel ketoconazole (KTZ)-loaded solid lipid nanoparticles (KTZ-SLNs; 2% w/v KTZ) for enhanced permeation across skin. KTZ-SLNs were evaluated for size, distribution, zeta potential (ZP), percent entrapment efficiency (%EE), drug release, morphology (HRTEM and FESEM), thermal behaviour (DSC), spectroscopic (FTIR), and solid-state/diffraction characterization (X-ray diffraction, XRD). Moreover, ex vivo permeation and drug deposition into rat skin were conducted using Franz diffusion cell. The same was confirmed using human dermatome skin and fluorescence, confocal Raman, and vibrational ATR-FTIR microscopic methods. An in vivo dermatokinetics study was performed in rats to assess the extent of KTZ permeation into the skin. Stability including accelerated and photostability studies were conducted at different temperatures (2-8, 30, and 40 °C) for 12 months. The spherical, optimized KTZ-SLN formulation (KOF1) showed particle size of 293 nm and high EE of 88.5%. Results of FTIR, DSC, and XRD confirmed formation of KTZ-SLNs and their amorphous nature due to presence of KTZ in a dissolved state in the lipid matrix. In vitro release was slow and sustained whereas ex vivo permeation parameters were significantly high in KTZ-SLNs as compared to free drug suspension (KTZ-SUS) and marketed product (Nizral®; 2% KTZ w/v). Drug retention was 10- and five-fold higher than KTZ-SUS and marketed product, respectively. In vivo dermatokinetics parameters improved significantly with SLN formulation (410-900% enhanced). Confocal Raman spectroscopy experiment showed that KTZ-SLNs could penetrate beyond the human stratum corneum into viable epidermis. Fluorescent microscopy also indicated improved penetration of KTZ-SLNs. KTZ-SLNs were photostable and showed long-term stability over 12 months under set conditions.

A voltammetric sensor based on a carbon black and chitosan-stabilized gold nanoparticle nanocomposite for ketoconazole determination

A modified glassy carbon electrode with carbon black (CB) and gold nanoparticles (AuNPs) within a crosslinked chitosan (CTS) film is proposed in this work. The electroanalytical performance of the modified CB-CTS-AuNPs/GCE has been evaluated towards the voltammetric sensing of ketoconazole (KTO), a widespread antifungal drug. The nanocomposite was characterized by scanning electron microscopy, X-ray diffraction spectroscopy, and electrochemistry experiments. The evaluation of the electrochemical behaviour of KTO on the proposed modified electrode shows an irreversible oxidation process at a potential of +0.65 V (vs. Ag/AgCl (3.0 mol L^-1 KCl)). This redox process was explored to carry out KTO sensing using square-wave voltammetry. The analytical curve was linear in the KTO concentration range from 0.10 to 2.9 μmol L^-1, with a limit of detection (LOD) of 4.4 nmol L^-1 and a sensitivity of 3.6 μA L μmol^-1. This modified electrode was successfully applied to the determination of KTO in pharmaceutical formulations and biological fluid samples.

Increasing the Robustness of Biopharmaceutical Precipitation Assays - Part I: Derivative UV Spectrophotometric Method Development for in-line Measurements

In vitro precipitation assays are often applied to support drug and formulation development. Current methods applied to quantify the amount of dissolved drug, in particular (U)HPLC, require time-consuming sample preparation. Furthermore, small precipitates formed during the nucleation phase may not be removed quantitatively by filtration or centrifugation of the sample. Given the drawbacks of standard (U)HPLC analyses during the application in transfer experiments, it was the aim of this work to develop a robust and simple to implement in-line UV spectrophotometric method which accurately reflects the precipitation profile obtained from in vitro transfer assays. Based on the three model compounds cinnarizine, dipyridamole, and ketoconazole, the manuscript describes the development of a design of experiments (DoE) based approach to develop derivative UV spectrophotometric methods accounting for the change in media composition over time due to the dilution of simulated intestinal with simulated gastric fluid. An R script was developed which automatically identifies suitable wavelengths for in-line measurements. As an outcome of this study, a fast, robust, accurate, and specific derivative UV spectrophotometric methodology for measuring the concentration of dissolved drugs in in vitro transfer experiments was successfully developed. This method can flexibly be applied to multi-compartmental precipitation assays.

Ketoconazole-induced transient hypoadrenocorticism in a dog

A 6-year-old, spayed female, mixed breed boxer dog was presented for decreased appetite, polyuria and polydipsia, and lethargy 9 days after treatment with ketoconazole for Malassezia pododermatitis. Ketoconazoleinduced hypoadrenocorticism was confirmed with an adrenocorticotropic hormone (ACTH) stimulation test, and ketoconazole was discontinued. Clinical signs resolved 48 hours after initiation of prednisone, and resolution of glucocorticoid insufficiency was confirmed with a repeat ACTH stimulation test 48 hours after a 10-day course of prednisone. Glucocorticoid insufficiency after administration of a commonly used dermatological dose of ketoconazole has not been previously reported in veterinary medicine but should be considered in patients with adverse effects while receiving ketoconazole. Key clinical message: Iatrogenic hypoadrenocorticism may occur in dogs treated with commonly used dermatological doses of ketoconazole. The disease is likely transient, but steroid supplementation may be required in some patients to resolve clinical signs, especially in the presence of concurrent illness or stress.

[Pharmacological treatment in adrenal Cushing's syndrome.]

ACTH-independent adrenal Cushing's syndrome is the least common form of endogenous hypercortisolism. Recently, advances in genetics have allowed the description of several forms different to pathogenetic etiology, morphostructural characteristics and evolution towards the hypercortisolism. Alongside these, the adrenocortical carcinoma is also frequently responsible of a hypercortisolism clinical picture. The availability of steroidogenesis inhibitors, such as metyrapone and ketoconazole, provides to endocrinologist a therapeutic chance against different metabolic disorders sustained by hypercortisolism. Mitotane, an adrenolitic compound, is used alone in adjuvant therapy or in combination with different chemotherapy drugs in the treatment of adrenocortical carcinoma and in the treatment of severe Cushing's syndrome.

[New drugs for small animals in 2014]

In 2014, six active pharmaceutical ingredients were released on the German market for small animals. Those are the ektoparasiticide of the isoxazoline group afoxolaner (NexGard®) and fluralaner (Bravecto®) and the neonicotinoid dinotefuran (Vectra 3D, Vectra Felis), the antidiabetic protamine zinc insulin of human origin (ProZinc®), the antifungal agent ketoconazole (Fugazid®) as well as the cytostatic drug oclacitinib (Apoquel®). Two substances were authorized for an additional species. The antiparasiticide eprinomectin and the antibiotic clindamycin were also authorized for use in cats. In addition, two active pharmaceutical ingredients, which were approved 2014 for use in human medicine and are of potential interest to veterinary medicine, are discussed. These are the antihypertensive drug riociguat and the urological substance mirabegron.

Gender determines ACTH recovery from hypercortisolemia in healthy older humans

OBJECTIVE

Available clinical data raise the possibility that stress-adaptive mechanisms differ by gender. However, this notion has not been rigorously tested in relation to cortisol-mediated negative feedback.

MATERIALS/METHODS

Degree of ACTH inhibition during and recovery from an experimental cortisol clamp was tested in 20 healthy older subjects (age 60±2.2 y). Volunteers received oral placebo or ketoconazole (KTCZ) to inhibit adrenal steroidogenesis along with i.v. infusions of saline or a low vs high physiological dose of cortisol in a prospectively randomized double-blind, placebo-controlled design. ACTH and cortisol concentrations were measured every 10 min during the feedback-clamp phase and thereafter (recovery or escape phase). Corticosteroid-binding globulin (CBG) was measured, and free cortisol concentrations were calculated.

RESULTS

Gender did not determine mean ACTH concentrations during the saline or cortisol feedback-clamp phases per se. However, women had markedly impaired ACTH recovery after stopping both low- and high-dose cortisol infusions compared with men (P=0.005, KTCZ/low-dose cortisol arm; and P=0.006, KTCZ/high-dose cortisol arm). Decreased ACTH recovery in women was accompanied by lower total and free cortisol concentrations, pointing to heightened feedback inhibition of hypothalamo-pituitary drive of ACTH secretion as the main mechanism.

CONCLUSIONS

In summary, gender or a factor related to gender, such as sex steroids or body composition, determines recovery of ACTH secretion from cortisol-enforced negative feedback. Attenuated ACTH recovery in post-menopausal women may have relevance to sex differences in stress-related adaptations.

Comparative evaluation of ketoconazole-β-cyclodextrin systems prepared by coprecipitation and kneading

Ketoconazole (KZ), an imidazole antifungal, was formulated into inclusion complexes via coprecipitation and kneading with β-cyclodextrin (β-CD) as a carrier in 1:1 and 1:2 drug to carrier ratios. The KZ-β-CD solid complexes were characterized by X-ray diffraction and differential scanning calorimetry (DSC). The diffraction pattern of the pure drug revealed the drug to be highly crystalline in nature, as indicated by numerous distinctive peaks. The lack of numerous distinctive peaks of the drug in KZ-β-CD complexes prepared by the two methods revealed that a large number of the drug molecules were dissolved in a solid-state carrier matrix with an amorphous structure. The thermograms of the KZ-β-CD complexes showed a strong reduction in the intensity and broadening of drug peaks somewhat in both kneading and coprecipitation systems, suggesting that the drug is monomolecularly dispersed in the β-CD cavity. The prepared tablets of KZ-β-CD solid complexes prepared by the two methods were evaluated for their quality control testing, and an in vitro release study and the results of quality control complied with pharmacopeial requirements and the release profiles indicated complete drug release after 30 min. The kinetic parameters obtained from release data were analyzed in order to explain the mechanism of drug release and revealed non-Fickian transport. Accelerated stability testing at 35°C, 45°C, and 55°C and at 75% relative humidity was carried out for six months and revealed somewhat stable systems as indicated by a t(90) of about 2 years for both KZ-β-CD systems. A microbiological in vitro assay of KZ from the prepared tablets was performed using Candida albicans as a model fungus, and KZ had improved microbiological activity when administered as an inclusion complex with β-CD. The results confirmed the benefit of using CDs as a useful tool to enhance the dissolution and hence bioavailability of poorly water-soluble drugs by forming solubilizing systems when exposed to gastrointestinal fluid.

Pharmacokinetic modelling of pentoxifylline and lisofylline after oral and intravenous administration in mice

The aim of this study was to develop pharmacokinetic models for pentoxifylline (PTX) and the R(-)-enantiomer of the PTX metabolite 1, lisofylline (LSF), in order to identify some factors influencing the absorption of these compounds from the intestines and to clarify mechanisms involved in their non-linear pharmacokinetics. Serum samples were collected after oral and intravenous administration of PTX and LSF to male CD-1 mice at two different doses. In addition, both compounds under investigation were coadministered with a modulator of drug transporters, verapamil, and an inhibitor of cytochrome P450 (CYP) 3A4, ketoconazole. Pharmacokinetic analysis revealed that a one-compartment model with Michaelis-Menten type absorption and elimination best described the pharmacokinetics of PTX, whereas the LSF concentration-time data were adequately fitted to a two-compartment model with a first-order absorption and Michaelis-Menten type elimination process. Both coadministered compounds significantly decreased the area under the concentration-time curve from 0 to 60 min calculated for PTX and increased the value of this parameter for LSF. The results of this study indirectly suggest that saturation of drug transport across intestinal cells and elimination from the central compartment may be responsible for the non-linear pharmacokinetics of PTX, whereas in the case of LSF, the dose dependency in the pharmacokinetics is solely related to the elimination from the central compartment. It seems that the observed changes in PTX and LSF concentrations after coadministration with verapamil and ketoconazole may be clinically significant, especially after chronic treatment, however further studies are necessary to assess the importance of these interactions in humans.

[Oral isolates of Saccharomyces in patients with oral fungal infection and their susceptibility to antifungal drugs]

OBJECTIVE

To understand whether there were any differences of sensitivity to antifungals between the species of Saccharomyces (Candidas) isolated from oral cavity in the patients with oral candidosis and healthy volunteers. Observing the effect of nystatin topically used and discussing preliminarily the relationship between MIC and clinical effect in order to offer reference for clinical treatment.

METHODS

The experiment was carried on 61 patients with candidosis in experimental group and 43 healthy volunteers in control group and isolates of Saccharomyces were obtained by the oral rinse technical method. To isolate and identify Saccharomyces in oral cavity by CHROMagar Saccharomyces culture medium and test the MIC of several antifungal agents such as nystatin, ketoconazole and fluconazole against Saccharomyces by NCCLSM27-A microdilution assay. 31 patients in experimental group were administered with nystatin, observing the clinical effect a week later and comparing the results with the MIC.

RESULTS

(1) The incidence of Saccharomyces was 78.69% and 30.23% in experimental group and control group respectively. The proportion of Saccharomyces albicans was 80.70% (experimental group) and 92.31% (control group). (2) There was no significant difference between the susceptibility of Saccharomyces albicans to fluconazole and ketoconazole (P > 0.05), but the MIC data of azole antifungals were lower than nystatin. (3) The susceptibility of Saccharomyces albicans to fluconazole, ketoconazole and nystatin was 95.65%, 80.43%, and 89.13%, and a few isolates were resistent to antifungal agents. (4) The effectiveness of nystatin was 87.10%, and there were a few cases which MIC differs from the clinical effect.

CONCLUSION

At present, the resistance of Saccharomyces in patients with oral fungal infection is not significant, most Saccharomyces albicans are sensitive to fluconazole, ketoconazole and nystatin. The MIC of fluconazole and ketoconazole are lower than nystatin, implying when the clinical effect of nystain is poor, to use an azole antifungal is optional. The MIC is relative to therapeutic effect to some degree, but it is not consistent completely.

Efficient short-term control of hypercortisolaemia by low-dose etomidate in severe paediatric Cushing's disease

BACKGROUND

Paediatric Cushing's disease (CD) is rare, but is associated with considerable morbidity and requires effective treatment. Control of hypercortisolaemia is recommended prior to definitive therapy by transsphenoidal pituitary surgery with selective adenomectomy. We describe a 6.2-year-old male with severe hypercortisolaemia and life-threatening complications of Cushing's disease. Control of cortisol with metyrapone and ketoconazole was ineffective, and due to his deteriorating condition, the decision was taken to proceed to bilateral adrenalectomy.

METHODS

Low-dose IV infusion of etomidate, with dose titration according to serum cortisol levels, was administered.

RESULTS

Etomidate infusion (3.0 mg/h i.v.) decreased serum cortisol from 1,250 to 250 nmol/l within 24 h. Combined etomidate and hydrocortisone therapy was maintained to provide stable serum cortisol levels within the desired range for 12 days prior to successful bilateral adrenalectomy.

CONCLUSION

In our experience, etomidate was effective and safe for short-term control of severe hypercortisolaemia in a severely ill child.

Antifungal agents of use in animal health--chemical, biochemical and pharmacological aspects

A limited number of antifungal agents is licensed for use in animals, however, many of those available for the treatment of mycoses in humans are used by veterinary practitioners. This review includes chemical aspects, spectra of activity, mechanisms of action and resistance, adverse reactions and drug interactions of the antifungals in current use.

Effect of raised plasma beta endorphin concentrations on peripheral pain and angina thresholds in patients with stable angina

OBJECTIVE

To determine whether changes in plasma concentrations of beta endorphins alter angina threshold and peripheral pain threshold in patients with stable angina.

DESIGN

Latin square design comparison of angina thresholds by exercise treadmill test and peripheral pain thresholds using a radiant heat source in eight patients with stable angina under control conditions, after stimulation of pituitary beta endorphin release by ketoconazole, after suppression of pituitary beta endorphin release by dexamethasone, and after blockade of opioid receptors by intravenous naloxone.

RESULTS

An approximately fivefold increase in circulating concentrations of beta endorphins was found after administration of ketoconazole (mean (SEM): 13.9 (1.2) v 73.8 (6.2) pg/ml; p < 0.05), which was associated with an increase in peripheral pain threshold to a radiant heat source (time to onset of pain perception 72 (19) v 123 (40) seconds; p < 0.05), but no significant difference in angina threshold. A reduction in circulating concentrations of beta endorphins after pretreatment with dexamethasone was statistically non-significant (13.9 (1.2) v 9.0 (1.5) pg/ml; NS) and was not associated with any change in either peripheral pain or angina thresholds. No effects were seen after blockade of opioid receptors by previous administration of intravenous naloxone.

CONCLUSIONS

Increased plasma concentrations of beta endorphins alter peripheral pain threshold but not angina threshold in patients with stable angina pectoris.

Antifungal agents. Part II. The azoles

Before 1978, amphotericin B and flucytosine were the only drugs available for the treatment of systemic fungal infections. The imidazoles, miconazole and ketoconazole, were introduced during the next 3 years. Intravenously administered miconazole served a limited therapeutic role and is no longer available. Orally administered ketoconazole, an inexpensive, effective, and convenient option for treating mucosal candidiasis, was widely used for a decade because it was the only available oral therapy for systemic fungal infections. During the 1990s, use of ketoconazole diminished because of the release of the triazoles--fluconazole and itraconazole. Fluconazole is less toxic and has several pharmacologic advantages over ketoconazole, including penetration into the cerebrospinal fluid. In addition, it has superior efficacy against systemic candidiasis, cryptococcosis, and coccidioidomycosis. Despite a myriad of drug interactions and less favorable pharmacologic and toxicity profiles in comparison with fluconazole, itraconazole has become a valuable addition to the antifungal armamentarium. It has excellent activity against sporotrichosis and seems promising in the treatment of aspergillosis. Itraconazole has replaced ketoconazole as the therapy of choice for nonmeningeal, non-life-threatening cases of histoplasmosis, blastomycosis, and paracoccidioidomycosis and is effective in patients with cryptococcosis and coccidioidomycosis, including those with meningitis. Further investigation into the development of new antifungal agents is ongoing.

Diazepam metabolism by cDNA-expressed human 2C P450s: identification of P4502C18 and P4502C19 as low K(M) diazepam N-demethylases

The present study provides a detailed kinetic analysis of diazepam metabolism by all four known members of the human P4502C subfamily expressed from their cDNAs in Escherichia coli. Both P4502C18 and P4502C19 were found to be low K(M) diazepam N-demethylases with apparent K(M) values of 24 +/- 4 microM and 21 +/- 3 microM, respectively. These values closely resemble the low K(M) component of diazepam N-demethylase activity exhibited by human liver microsomes. In addition, P4502C19 also catalyzed diazepam 3-hydroxylation with a K(M) value of 21 +/- 9 microM. Although P4502C8 was essentially inactive in catalyzing diazepam metabolism, P4502C9 catalyzed the N-demethylation with a relatively high K(M) of 80 +/- 15 microM and an overall 3- to 6-fold lower catalytic efficiency, compared with P4502C18 and P4502C19, respectively. At a substrate concentration of 10 microM, diazepam N-demethylation in a panel of human liver microsomes was inhibited 42 +/- 12% (mean +/- SD, N = 6) by a polyclonal anti-CYP2C antibody. In the same experiment, 3-hydroxylation remained unaffected (<10% inhibition). 1 microM of the CYP3A inhibitor ketoconazole inhibited 37 +/- 19% of the N-demethylation and 86 +/- 5% of 3-hydroxylation. Estimates of relative contributions to diazepam N-demethylation of P4502C9 (8 +/- 4%), P4502C18 (<2%), and P4502C19 (33 +/- 14%) and to diazepam 3-hydroxylation of P4502C19 (9 +/- 3%) based on the kinetic parameters of the recombinant enzymes and on specific contents of the individual 2C P450s determined in immunoblots are consistent with the inhibition data. In conclusion, these data confirm that both P4502C19 and P4503A are major contributors to human liver microsomal diazepam N-demethylation at low substrate concentrations, whereas P4503A is the major enzyme responsible for 3-hydroxylation.

Selective biotransformation of the human immunodeficiency virus protease inhibitor saquinavir by human small-intestinal cytochrome P4503A4: potential contribution to high first-pass metabolism

Saquinavir is a HIV protease inhibitor used in the treatment of patients with acquired immunodeficiency syndrome, but its use is limited by low oral bioavailability. The potential of human intestinal tissue to metabolize saquinavir was assessed in 17 different human small-intestinal microsomal preparations. Saquinavir was metabolized by human small-intestinal microsomes to numerous mono- and dihydroxylated species with K(M) values of 0.3-0.5 microM. The major metabolites M-2 and M-7 were single hydroxylations on the octahydro-2-(1H)-isoquinolinyl and (1,1-dimethylethyl)amino groups, respectively. Ketoconazole and troleandomycin, selective inhibitors of cytochrome P4503A4 (CYP3A4), were potent inhibitors for all oxidative metabolites of saquinavir. The cytochrome P450-selective inhibitors furafylline, fluvoxamine, sulfaphenazole, mephenytoin, quinidine, and chlorzoxazone had little inhibitory effect. All saquinavir metabolites were highly correlated with testosterone 6beta-hydroxylation and with each other. Human hepatic microsomes and recombinant CYP3A4 oxidized saquinavir to the same metabolic profile observed with human small-intestinal microsomes. Indinavir, a potent HIV protease inhibitor and a substrate for human hepatic CYP3A4, was a comparatively poor substrate for human intestinal microsomes and inhibited the oxidative metabolism of saquinavir to all metabolites with a Ki of 0.2 microM. In addition, saquinavir inhibited the human, small-intestinal, microsomal CYP3A4-dependent detoxication pathway of terfenadine to its alcohol metabolite with a Ki value of 0.7 microM. These data indicate that saquinavir is metabolized by human intestinal CYP3A4, that this metabolism may contribute to its poor oral bioavailability, and that combination therapy with indinavir or other protease inhibitors may attenuate its low relative bioavailability.

Temporal decline in filling prescriptions for terfenadine closely in time with those for either ketoconazole or erythromycin

Temporal changes in the rates of filling terfenadine prescriptions within 2 days of those for either oral erythromycin or oral ketoconazole were described with use of paid pharmacy claims data from 1988 through 1994 in state Medicaid programs from Michigan and Ohio and in a large health maintenance organization. There were rapid and significant declines in the rates of filling prescriptions for either erythromycin or ketoconazole within 2 days of prescriptions for terfenadine in all three databases that coincided with 1992 publicity about the cardiovascular risk of terfenadine. These findings suggest that the use of terfenadine with contraindicated medications has declined in response to relabeling and publicity concerning the safe use of terfenadine. Further study is necessary to estimate the absolute level of concurrent use of terfenadine with contraindicated medications.

Oral therapeutic agents in fungal nail disease

Oral griseofulvin has been the first-line drug in the therapy of dermatophyte onychomycosis for many years. Even when used long-term, it is effective in only about 30% of patients. Ketoconazole is not much more effective than griseofulvin in toenail infections, and there are significant problems with hepatotoxicity. Recently the triazoles, itraconazole and fluconazole, and the allylamine, terbinafine, were introduced and are believed to be potentially suitable for the oral treatment of fungal nail infection. Terbinafine is particularly effective in the treatment of dermatophyte onychomycosis, with a much shorter treatment period than griseofulvin. Cure rates of well over 80% have been noted in fingernail and toenail infection during treatment periods of 6 and 12 weeks, respectively. Itraconazole, 200 mg/day, has been noted in some studies to be similarly effective in the same treatment period. Few studies of fluconazole in nail infection have been carried out. These new agents appear to be safe, and results thus far suggest that they will soon overtake griseofulvin as the drug of choice in the oral therapy of nail infection.

Site of action of low dose ketoconazole on androgen biosynthesis in men

Ketoconazole inhibits testosterone biosynthesis in men, but the exact site of its action on the androgen pathway remains to be established. To examine this question, we measured several steroids in the androgen and glucocorticoid pathways in normal men before and after receiving either a single dose of 200 mg ketoconazole or placebo in a cross-over randomized trial. Total and free plasma testosterone fell to levels 60% below basal within 4-8 h (P less than 0.02 in all) and then returned to control concentrations by 24 h after drug administration. The transient alterations of plasma testosterone correlated well with ketoconazole blood levels, which peaked at 2 h and fell exponentially thereafter. A compensatory increase in plasma LH at 24 h in the drug but not placebo group was consistent with the decrease in plasma testosterone. The levels of plasma androstenedione paralleled those of testosterone in the ketoconazole-treated subjects. In marked contrast, plasma 17 alpha-hydroxyprogesterone increased at 4-8 h (all P less than 0.02) before returning to basal values at 24 h. This rise in precursor with fall in product steroid implicated an effect of ketoconazole on the C17-20 lyase enzyme. This conclusion was supported by the highly significant increase in the ratio of plasma 17 alpha-hydroxyprogesterone to androstenedione observed between 2 and 24 h after drug administration. The effect of ketoconazole at this dose level appeared relatively specific, since no decrements in plasma cortisol or 11-desoxycortisol were found. During chronic administration of 200 mg ketoconazole daily, decrements of plasma testosterone 2-4 h after drug administration were minimal and documented only by paired comparisons within subjects but not by unpaired tests between normal men and men receiving drug. The lack of major effects on testosterone levels long term at this dosage probably explain why few androgen-related side effects with this drug were previously reported. Ketoconazole, therefore, represents another compound with relatively selective effects on a cytochrome P-450-mediated steroid hydroxylation step, namely that involved with C17-20 lyase.

Successful ketoconazole treatment of protothecosis with ketoconazole-associated hepatotoxicity

A 46-year-old woman had a chronic, unresponsive wrist infection that was proved to be due to the algaelike organism Prototheca wickerhamii. Treatment with ketoconazole resulted in prompt improvement and ultimate healing. Therapy was complicated by hepatitis that was ketoconazole-related. Ketoconazole may be effective and easily administered therapy for this generally unresponsive infection.

Effect of pH on disintegration and dissolution of ketoconazole tablets

The effect of pH on the in vitro disintegration, dissolution, and solubility of ketoconazole tablets was studied. One 200-mg ketoconazole tablet was added to each of five different buffer solutions having pH values of 2 to 6;900 ml of each solution containing the ketoconazole was placed in a stationary basket dissolution device and stirred at 500 rpm at 37 degrees C for 60 minutes. Single 1-ml samples of each solution were obtained at 1,3, and 5 minutes after addition of the drug, and then every 5 minutes for the duration of the sampling period. This same procedure was repeated using two 200-mg tablets in the buffer solution at pH 3. The effect of pH on ketoconazole solubility was studied by gradually increasing the pH of a ketoconazole solution at pH 3 to pH 10. Samples of this solution were analyzed periodically after allowing a short period for equilibration of pH. All samples were assayed spectrophotometrically against blanks, and concentrations were determined by comparison with a standard curve. Disintegration of ketoconazole tablets occurred within 5 minutes in each buffer solution and was unaffected by pH. At pH 2 and 3, dissolution of ketoconazole was greater than 85% complete after five minutes, and all ketoconazole had dissolved after 30 minutes. As pH increased, the rate and extent of dissolution slowed; only 10% of ketoconazole was dissolved after 60 minutes at pH 6. Ketoconazole precipitated rapidly from solution as the pH of the dissolution medium exceeded 5.5. There was no difference in the rate or extent of dissolution of ketoconazole for the two doses studied at pH 3. In the buffer solutions tested, dissolution but not disintegration of ketoconazole tablets is pH-dependent. Dissolution characteristics of 200- and 400-mg doses of ketoconazole are similar at pH 3.