Menahydroquinone-4 may play a key role in regulating CCL5 expression induced by epidermal growth factor receptor inhibitors.

Epidermal growth factor receptor (EGFR) inhibitors frequently cause severe skin rash as a side effect, which is a critical burden for patients who continuously receive drug treatments. Several recent clinical trials have shown that vitamin K is effective against these side effects; however, the underlying mechanisms remain unclear. EGFR inhibitors induce C-C motif chemokine ligand 5 (CCL5) in dermopathy. We hypothesized that menahydroquinone-4 (MKH), the active form of menaquinone-4 (MK-4, vitamin K2(20)), supplied by biosynthesis or external delivery, is essential for the suppressive effect on CCL5. The aim of this study was to explore the underlying mechanisms governing the relieving effects of MKH against skin rashes caused by EGFR inhibitors. The responses generated by EGFR inhibitors and the effect of MKH derivatives (two ester derivatives and MK-4) on them were evaluated using human skin cell lines (HaCaT and HSC-1). EGFR inhibitors downregulated UbiA prenyltransferase domain-containing protein-1 (UBIAD1, MKH synthetase) expression and MKH biosynthesis. Knockdown of UBIAD1 or γ-glutamyl carboxylase and treatment with warfarin upregulated CCL5 expression. MKH derivatives suppressed the CCL5 expression induced by EGFR inhibitors. Our data strongly suggest that MKH is involved in suppressing CCL5 expression and alleviating the skin damage caused by EGFR inhibitors.

Cationic Ester Prodrugs of Curcumin with N,N-dimethyl Amino Acid Promoieties Improved Poor Water Solubility and Intestinal Absorption.

PURPOSE: Although curcumin (Cur) has powerful pharmacological effects, its use in medicine has not been established yet. The oral bioavailability (BA) of Cur is limited because of its poor water solubility. The purpose of this study was to confirm whether cationic N,N-dimethyl amino acid esters of Cur could act as prodrugs and improve its water solubility and oral bioavailability. METHODS: Two N,N-dimethyl amino acid esters of Cur were synthesized. The hydrolysis profile of the esters was evaluated using rat and human microsomes. A pharmacokinetic study after oral administration of the Cur ester derivatives was performed in rats and compared to the administration of suspended or dissolved Cur formulation. The anti-inflammatory effects of the Cur derivatives were evaluated using macrophage RAW 264.7 stimulated with lipopolysaccharide. RESULTS: Cur ester derivatives showed > 200 mM water solubility. The derivatives were reconverted to the parent compound (Cur) after cleavage of the ester bonds by microsomal esterase, indicating that the compounds could act as Cur prodrugs. The Cur prodrugs enhanced the absolute oral bioavailability of Cur by a 9- and threefold increase of suspended and dissolved Cur administration, respectively, thereby improving intestinal absorption. Cur prodrugs strongly attenuated COX2, iNOS, and ERK phosphorylation. CONCLUSIONS: The cationic N,N-dimethyl amino acid ester prodrugs of Cur improved the water solubility of Cur and enhanced oral bioavailability in rats. These Cur prodrugs may be good candidates for developing medicinal options previously unavailable due to the poor water solubility and oral BA of Cur.

Delivery of the reduced form of vitamin K2(20) to NIH/3T3 cells partially protects against rotenone induced cell death.

Mitochondria generate energy through the action of the electron transport chain (ETC) and ATP synthase. Mitochondrial malfunction can lead to various disorders, including neurodegenerative diseases. Several reports have shown that menaquinone-4 (MK-4, vitamin K2(20)), a safe drug for osteoporosis, may improve mitochondrial function. Here, we hypothesized that the efficient delivery of menahydroquinone-4 (MKH), an active form of MK-4, could exert a supporting effect. We verified the effects of MKH delivery on mitochondrial dysfunction by using MK-4 and MKH ester derivatives in NIH/3T3 mouse fibroblast cells treated with mitochondrial inhibitors. MK-4 and MKH derivatives suppressed cell death, the decline in mitochondrial membrane potential (MMP), excessive reactive oxygen species (ROS) production, and a decrease in intrinsic coenzyme Q9 (CoQ9) induced by rotenone (ROT, complex I inhibitor). MK-4 and MKH derivatives delivered MKH to NIH/3T3 cells, acting as an effective MKH prodrug, proving that the delivered MKH may reflect the mitigation effects on ROT-induced mitochondrial dysfunction. MKH prodrugs are also effective against 3-nitropropionic acid (3-NP, complex II inhibitor) and carbonyl cyanide-m-chlorophenylhydrazone (CCCP, uncoupler)-induced cell death. In conclusion, MKH delivery may mitigate mitochondrial dysfunction by maintaining MMP, ROS, and CoQ9, indicating that MKH prodrugs may be good candidates for treating mitochondrial disorders.

Cationic N,N-Dimethylglycine Ester Prodrug of 2R-α-Tocotrienol Promotes Intestinal Absorption via Efficient Self-Micellization with Intrinsic Bile Acid Anion.

The intestinal absorption of hydrophobic compounds is severely influenced by their transportation rate through the unstirred water layer in the intestinal lumen. A member of the vitamin E family, α-Tocotrienol (α-T3) has remarkable pharmacological effects, but its intestinal absorption is hampered due to its hydrophobicity. Here, we prepared three ester derivatives of 2R-α-T3, and we selected a suitable prodrug compound using rat plasma and liver microsomes. The micellization profile of the selected compound in the presence of taurocholic acid (TCA) was evaluated. After gastrostomy administration of the prodrug candidate or α-T3 solution containing TCA, AUC values were determined for α-T3 in plasma obtained from bile duct-ligated rats. Among the three types in the efficiency of the reconversion to the parent drug, α-T3 N,N-dimethylglycinate (α-T3DMG) was the best prodrug; α-T3DMG formed mixed micelles via ion pairs with anionic TCA. The solubility of α-T3DMG in n-octanol/water depended on its ratio to TCA. The AUC after α-T3DMG administration to ligated rats was 2-fold higher than that after α-T3 administration, suggesting a smooth interaction with intrinsic bile acids. In conclusion, utilization of the prodrug synthesized using N,N-dimethylglycine ester may be a beneficial approach to promote intestinal absorption of α-T3 via self-micellization with intrinsic bile acid.

Growth Inhibitory Effects of Ester Derivatives of Menahydroquinone-4, the Reduced Form of Vitamin K2(20), on All-Trans Retinoic Acid-Resistant HL60 Cell Line.

The first-choice drug for acute promyelocytic leukemia (APL), all-trans retinoic acid (ATRA), frequently causes drug-resistance and some adverse effects. Thus, an effective and safe agent for ATRA-resistant APL is needed. Menaquinone-4 (MK-4, vitamin K2(20)), used for osteoporosis treatment, does not have serious adverse effects. It has been reported that MK-4 has growth-inhibitory effects on HL60 cells by inducing apoptosis via the activation of Bcl-2 antagonist killer 1 (BAK). However, the effect of MK-4 on ATRA-resistant APL has not been reported. Here, we show that ester derivatives of menahydroquinone-4 (MKH; a reduced form of MK-4), MKH 1,4-bis-N,N-dimethylglycinate (MKH-DMG) and MKH 1,4-bis-hemi-succinate (MKH-SUC), exerted strong growth-inhibitory effects even on ATRA-resistant HL60 (HL-60R) cells compared with ATRA and MK-4. MKH delivery after MKH-SUC treatment was higher than that after MK-4 treatment, and the results indicated apoptosis induced by BAK activation. In contrast, for MKH-DMG, reconversion to MKH was slow and apoptosis was not observed. We suggest that the ester forms, including monoesters of MKH-DMG, exhibit another mechanism independent of apoptosis. In conclusion, the MKH derivatives (MKH-SUC and MKH-DMG) inhibited not only HL60 cells but also HL-60R cells, indicating a potential to overcome ATRA resistance.

Evaluation of photostability and phototoxicity of esterified derivatives of ubiquinol-10 and their application as prodrugs of reduced coenzyme Q10 for topical administration.

Ubiquinol-10 (UqH-10), the fully reduced form of ubiquinone-10 (Uq-10, coenzyme Q10 ), is an antioxidant and is involved in energy production. However, physicochemical disadvantages, such as rapid oxidation, water-insolubility, photoinstability, and phototoxicity, limit its application. We previously reported that UqH-10 1,4-bis-N,N-dimethylglycinate improved the oxidation susceptibility and poor bioavailability of UqH-10 in rats. Herein, we evaluated the photochemical properties of UqH-esterified derivatives (N,N-dimethylglycinate, hemi-succinate, ethylsuccinate, and hemi-glutarate). Photostability was examined by irradiation using artificial sunlight and monochromatic light. The concentration of each compound was determined using LC-MS/MS. Phototoxicity was assessed by singlet oxygen and superoxide assays. Delivery of UqH-10 via UqH-esters to the HaCaT human keratinocyte cell line was determined using LC-MS/MS. UqH-esters showed higher photostability to artificial sunlight than Uq-10 and UqH-10. Uq-10 and UqH-10 were rapidly degraded by monochromatic light at 279 nm, whereas UqH-esters were more stable. UVA and/or UVB irradiation generated high levels of singlet oxygen and superoxide in Uq-10, whereas UqH-esters were unreactive. Additionally, UqH-esters effectively delivered UqH-10 to HaCaT cells following efficient uptake in their ester forms and ester bond hydrolysis in the cells. In conclusion, UqH-ester derivatives exhibit higher photostability and lower phototoxicity compared with Uq-10 and UqH-10.

Atypical Antipsychotic Drug Ziprasidone Protects against Rotenone-Induced Neurotoxicity: An In Vitro Study.

Schizophrenia is a severe, chronic mental illness characterized by delusions, hallucinations, negative symptoms, and cognitive dysfunction. Recently, several studies have demonstrated that the pathogenesis of schizophrenia involves mitochondrial dysfunction and oxidative stress. However, the effect of antipsychotic drugs for these events has been poorly investigated. In the present study, we evaluated the neuroprotective effect of an atypical antipsychotic drug, ziprasidone (ZPD), on rotenone (ROT)-induced neurotoxicity involving oxidative stress in PC12 cells. Our data showed that ZPD treatment promoted the translocation of NF-E2-related factor-2 (Nrf2) from cytoplasm to nucleus and activated the expression of its target genes NAD(P)H quinone oxidoreductase (NQO-1), catalase (CAT), and heme oxygenase (HO-1). Additionally, ZPD prevented ROT-induced cell death and intracellular reactive oxygen species production. Interestingly, the use of serotonin 5-HT1A receptor antagonist 1-(2-methoxyphenyl)-4 (4-(2-phtalimido) butyl) piperazine (NAN-190) completely blocked the protective effect of ZPD against ROT-induced cell death. Our results demonstrate the neuroprotective effect of ZPD against ROT-induced neurotoxicity and suggest that ZPD may be a potential candidate for the prevention of mitochondrial dysfunction and oxidative stress in schizophrenia.

Ester derivatives of phyllohydroquinone effectively deliver the active form of vitamin K1 topically, owing to their non-photosensitivity.

Topical application of phylloquinone (PK) is beneficial to the skin; however, its topical use is limited in Europe owing to its photosensitive properties such as photodegradation and phototoxicity. We evaluated the suitability of ester derivatives of phyllohydroquinone (PKH), the active form of PK, for topical application to overcome the abovementioned problems of PK. We used the PKH derivatives PKH-1,4-bis-N,N-dimethylglycinate hydrochloride (PKH-DMG) and PKH-1,4-bis-hemisuccinate (PKH-SUC) for our studies. Photostability was determined by measuring the residual concentration after irradiation with artificial sunlight and multi-wavelength light. Phototoxicity after ultraviolet A (UVA) irradiation was assessed by measuring drug-induced singlet oxygen and intracellular reactive oxygen species (ROS) generation, and cell viability of a human epidermal keratinocyte cell line (HaCaT). Delivery of PKH into HaCaT cells was assessed by measuring PK epoxide (PKO) levels. The PKH derivatives showed higher photostability than PK. After UVA irradiation, PK induced high singlet oxygen levels and intracellular ROS generation, and reduced cell viability, whereas the PKH derivatives showed no effects. The PKH derivatives increased intracellular PKO levels. AUCPKO(0-72 h) values after PKH-DMG and PKH-SUC treatments were 0.741- and 22.9-fold higher than that after PK treatment, respectively. In conclusion, PKH derivatives act as PKH prodrugs and are suitable for topical application without the need for special protection from light.

Novel Cationic Prodrug of Ubiquinol-10 Enhances Intestinal Absorption via Efficient Formation of Nanosized Mixed-Micelles with Bile Acid Anions.

The aim of this study was to develop a prodrug of ubiquinol-10 (UqH-10), the active form of ubiquinone-10 (Uq-10), for oral delivery. Bioavailability of UqH-10 is hampered by its high susceptibility to oxidation and water-insolubility. We prepared three novel N,N-dimethylglycine ester derivatives of UqH-10, including a 1-monoester (UqH-1-DMG), 4-monoester (UqH-4-DMG), and 1,4-bis-ester (UqH-DMG), and assessed their physicochemical properties in vitro and in vivo. UqH-DMG spontaneously formed an aqueous micelle solution comprising 20 nm particles at 36.5 °C. Cationic UqH-DMG formed nano-sized (5 nm) mixed-micelles with taurocholic acid. Reconversion of the derivatives to UqH-10 was accelerated in human liver microsomes. The oral bioavailability of UqH-10 after administration of UqH-derivatives or Uq-10 was determined in fasted and postprandial rats secreting normal and high levels of bile, respectively. In fasted rats, plasma UqH-10 after UqH-derivatives administration reached Cmax at 2-3 h and after Uq-10 administration, it remained low. The AUC0-24h of UqH-10 after UqH-derivatives administration was 2-3-fold higher than that after Uq-10 administration. In postprandial rats, the Tmax of UqH-10 after UqH-derivatives administration was an hour earlier than after Uq-10 administration. In conclusion, cationic UqH-derivatives are convenient prodrugs that enhance UqH-10 bioavailability by forming nanosized mixed-micelles with intestinal bile acids.

Prodrugs for Skin Delivery of Menahydroquinone-4, an Active Form of Vitamin K2(20), Could Overcome the Photoinstability and Phototoxicity of Vitamin K2(20).

The effective delivery of menahydroquinone-4 (MKH), an active form of menaquinone-4 (MK-4, vitamin K2(20)), to the skin is beneficial in the treatment of various skin pathologies. However, its delivery through the application of MK-4 to the skin is hampered due to the photoinstability and phototoxicity of MK-4. This study aimed to evaluate the potential of ester prodrugs of MKH for its delivery into the skin to avoid the abovementioned issues. The ester prodrugs, MKH 1,4-bis-N,N-dimethylglycinate hydrochloride (MKH-DMG) and MKH 1,4-bis-hemisuccinate (MKH-SUC), were prepared using our previously reported methods. Photostability was determined under artificial sunlight and multi-wavelength light irradiation, phototoxicity was determined by intracellular ROS formation and cell viability of UVA-irradiated human epidermal keratinocyte cells (HaCaT), and delivery of MKH into HaCaT cells was assessed by measuring menaquinone-4 epoxide (MKO) levels. MKH prodrugs showed higher photostability than MK-4. Although MK-4 induced cellular ROS and reduced cell viability after UVA irradiation, MKH prodrugs did not affect either ROS generation or cell viability. MKH prodrugs enhanced intracellular MKO, indicating effective delivery of MKH and subsequent carboxylation activity. In conclusion, these MKH prodrugs show potential for the delivery of MKH into the skin without photoinstability and phototoxicity.

Effects of fluvoxamine on nerve growth factor-induced neurite outgrowth inhibition by dexamethasone in PC12 cells.

In the present study, we examined the effects of fluvoxamine on nerve growth factor (NGF)-induced neurite outgrowth inhibition by dexamethasone (DEX) in PC12 cells. Fluvoxamine increased NGF-induced neurite outgrowth. Compared with co-treatment with NGF and fluvoxamine, p-Akt levels were higher than the values without fluvoxamine. The phosphorylated extracellular regulated kinase 1/2 levels were slightly increased by co-treatment with NGF and fluvoxamine. Fluvoxamine concentration-dependently improved NGF-induced neurite outgrowth inhibition by DEX. Fluvoxamine also improved the decrease in the NGF-induced p-Akt level caused by DEX. Interestingly, the sigma-1 receptor antagonist NE-100 blocked the improvement effects of fluvoxamine on NGF-induced neurite outgrowth inhibition by DEX. The selective sigma-1 receptor agonist PRE-084 also improved NGF-induced neurite outgrowth inhibition by DEX, which is blocked by NE-100. These results indicate that the improvement effects of fluvoxamine on NGF-induced neurite outgrowth inhibition by DEX may be attributable to the phosphorylation of Akt and the sigma-1 receptor.

Cholinesterase inhibitor rivastigmine enhances nerve growth factor-induced neurite outgrowth in PC12 cells via sigma-1 and sigma-2 receptors.

Rivastigmine (Riv) is a potent and selective cholinesterase (acetylcholinesterase, AChE and butyrylcholinesterase, BuChE) inhibitor developed for the treatment of Alzheimer's disease (AD). To elucidate whether Riv causes neuronal differentiation, we examined its effect on nerve growth factor (NGF)-induced neurite outgrowth in PC12 cells. At concentrations of 0-100 µM, Riv was non-toxic in PC12 cells. Riv caused dose-dependent (10-100 µM) enhancement of NGF-induced neurite outgrowth, which was completely inhibited by the TrkA antagonist GW-441756. By contrast, Riv-mediated enhancement of neurite outgrowth was not blocked by the acetylcholine receptor antagonists, scopolamine and hexamethonium. However, the sigma-1 receptor (Sig-1R) antagonist NE-100 and sigma-2 receptor (Sig-2R) antagonist SM-21 each blocked about half of the Riv-mediated enhancement of NGF-induced neurite outgrowth. Interestingly, the simultaneous application of NE-100 and SM-21 completely blocked the enhancement of NGF-induced neurite outgrowth by Riv. These findings suggest that both Sig-1R and Sig-2R play important roles in NGF-induced neurite outgrowth through TrkA and that Riv may contribute to neuronal repair via Sig-1R and Sig-2R in AD therapy.

Antitumor Effects and Delivery Profiles of Menahydroquinone-4 Prodrugs with Ionic or Nonionic Promoiety to Hepatocellular Carcinoma Cells.

Hepatocellular carcinoma (HCC) shows poor prognosis owing to its very frequent recurrence even after curative treatment. Thus, an effective and safe long-term chemopreventive agent is strongly in demand. Menahydroquinone-4 (MKH) is an active form of menaquinone-4 (MK-4, vitamin K2) that is involved in the synthesis of vitamin K-dependent proteins in the liver. We hypothesized that efficient delivery of MKH might be critical to regulate HCC proliferation. The discovery of a suitable prodrug targeting HCC in terms of delivery and activation could reduce the clinical dose of MK-4 and maximize efficacy and safety. We previously showed that MKH dimethylglycinate (MKH-DMG) enables effective delivery of MKH into HCC cells and exhibits strong antitumor effects compared with MK-4. In this study, we prepared anionic MKH hemi-succinate (MKH-SUC) and non-ionic MKH acetate (MKH-ACT), in addition to cationic MKH-DMG, and evaluated MKH delivery profiles and antitumor effects in vitro. MKH-SUC showed the highest uptake and the most efficient release of MKH among the examined compounds and exhibited rapid and strong antitumor effects. These results indicate that MKH-SUC might have a good potential as an MKH delivery system for HCC that overcomes the limitations of MK-4 as a clinical chemopreventive agent.

The Kampo medicine Yokukansan (YKS) enhances nerve growth factor (NGF)-induced neurite outgrowth in PC12 cells.

Accumulating evidence indicates that neurotrophic factor-like substances involved in the induction of neurotrophic factor synthesis may aid in the treatment of neurological disorders, such as Alzheimer's disease. Yokukansan (YKS), a traditional Kampo medicine, has been used for the treatment of anxiety and mood disorders. In the present study, we aimed to identify the signaling pathways associated with YKS-mediated enhancement of nerve growth factor (NGF)-induced neurite extension in rat pheochromocytoma (PC12) cells. Akt and extracellular-regulated kinase 1/2 (ERK1/2) phosphorylation levels were assessed by western blot analysis, in the presence of YKS and following the treatment with TrkA inhibitor, K252a. YKS treatment (NGF+YKS 0.5 group) enhanced NGF-induced neurite outgrowth and phosphorylation/activation of Akt and ERK1/2 in PC12 cells. Moreover, YKS-induced effects were inhibited by the treatment with the TrkA receptor antagonist K252a (NGF+YKS 0.5+K252a group); no significant difference in neurite outgrowth was observed between K252a-treated (NGF+YKS 0.5+K252a group) and NGF-K252a-treated cells (NGF+K252a group). However, neurite outgrowth in K252a-treated cells (NGF+K252a and NGF+YKS 0.5+K252a group) reached only one-third of the level in NGF-treated cells (NGF group). NGF-mediated Akt phosphorylation increased by YKS was also inhibited by K252a treatment (NGF+YKS 0.5+K252a group), but no significant difference in ERK1/2 phosphorylation was observed between NGF-YKS-K252a- and NGF-treated cells (NGF group). Our results indicate that YKS treatment enhanced NGF-induced neurite outgrowth via induction of Akt and ERK1/2 phosphorylation, following the binding of NGF to the TrkA receptor. These findings may be useful in the development of novel therapeutic strategies for the treatment of Alzheimer's disease.

Mechanism Underlying Linezolid-induced Thrombocytopenia in a Chronic Kidney Failure Mouse Model.

OBJECTIVE: To investigate the relationship between renal function and linezolid (LZD)-induced thrombocytopenia and elucidate the underlying mechanism using a chronic renal disease (CRD) mouse model. MATERIALS AND METHODS: CRD was induced in 5-week-old male Institute of Cancer Research (ICR) mice by 5/6 nephrectomy. After this procedure, LZD (25 and 100 mg/kg) was administered intraperitoneally once every day for 28 days. Platelet counts, white blood cell (WBC) counts, and hematocrit (HCT) levels were measured every 7 days. 2-14C-thymidine (0.185 MBq) was administrated intravenously to LZD-administered mice to evaluate the thymidine uptake ability of bone marrow. RESULTS: Platelet counts were significantly lower in the LZD-administered CRD group than in the LZD-nonadministered groups at 14, 21, and 28 days (P < 0.05); however, these changes were not observed in LZD-administered mice with normal renal function, regardless of the duration of LZD administration. No significant changes were observed in WBC counts or HCT levels in any LZD-administered CRD mouse. Moreover, radioactive levels in bone marrow were not significantly different in each group. CONCLUSIONS: These results indicate that LZD-induced decreases in platelet counts were enhanced by renal impairment in vivo, suggesting that LZD-induced thrombocytopenia is not caused by nonimmune-mediated bone marrow suppression.

Evaluation of pharmacokinetics and the stability of daptomycin in serum at various temperatures.

BACKGROUND: Daptomycin exhibits concentration-dependent antibacterial activity. By monitoring daptomycin serum concentrations, clinicians may be able to predict the effectiveness of treatments for infections more accurately. However, it has been reported that daptomycin concentrations in plasma samples stored at -20°C decrease approximately 25% after 4 weeks. The aim of this study was to evaluate the stability of daptomycin in serum at various temperatures. METHODS: Daptomycin serum samples were prepared and stored at different temperatures. The stability of daptomycin under various conditions was evaluated by sequential measurements of concentration. RESULTS: Although the loss of concentration of daptomycin in serum samples stored in freezers (-80°C and -20°C) was less than 10% after 168days (6 months), the concentrations in samples stored in a refrigerator (4°C) decreased by more than 70% over the same period. Furthermore, daptomycin concentrations in serum samples stored at close to body temperature (35°C, 37°C, and 39°C) decreased by more than 50% after only 24h. CONCLUSIONS: The results of the present study demonstrate that the measurement of serum concentrations of daptomycin needs to be performed rapidly. Furthermore, the degradation of daptomycin in serum may be involved in its elimination from the living body.

Comparison of predictive accuracy of teicoplanin concentration using creatinine clearance and glomerular filtration rate estimated by serum creatinine or cystatin C.

We compared the predictive accuracy of TEIC concentrations (TEIC_conc) calculated using either serum cystatin C (CysC) or serum creatinine (SCr) and the population mean method using the mean population parameter of TEIC_conc for Japan. We also compared the predicted TEIC_conc to measured TEIC_conc. Creatinine clearance (CLCr) predicted using the Cockcroft-Gault (C&G) equation with SCr was 45.23 mL/min (interquartile range [IQR]: 32.12-58.28), and the glomerular filtration rate (GFR) predicted using the Hoek equation with CysC was 45.23 mL/min (IQR: 35.40-53.79). The root mean-squared prediction error (IQR) based on CLCr predicted using the C&G equation with SCr was 6.88 (3.80-9.96) µg/mL, and that based on GFR predicted using the Hoek equation with CysC was 6.72 (3.77-9.68) µg/mL. Predicted TEIC_conc did not differ significantly between the two methods. The predictive accuracy of the TEIC_conc using the Hoek equation with CysC was similar to that of CLCr using the C&G equation with SCr. These findings suggest that the predictive accuracy of the TEIC_conc using CLCr based on the G&G equation and SCr might be sufficient for the initial dose adjustment of TEIC. Given that we were unable to confirm that CysC is the optimal method for predicting TEIC_conc, the expensive measurement of CysC might not be necessary.

Elevations of urinary pH may lower vancomycin serum concentration.

OBJECTIVE: This study investigated endogenous factors that may increase the elimination of vancomycin (VCM) in adult methicillin-resistant Staphylococcus aureus (MRSA) patients with pneumonia. METHODS: 48 patients (32 men and 16 women) admitted to the National Hospital Organization Kumamoto Medical Center for pneumonia due to MRSA were evaluated. VCM (500 - 2,000 mg/dose) was administered intravenously for 60 - 120 min at 8- - 12-h intervals. The dose of VCM prescribed was determined based on the treatment guidelines of the Infectious Diseases Society of America and was dependent on a patient's creatinine clearance. RESULTS: Univariate analysis identified that potassium value (K) (p = 0.081) and urinary pH (p = 0.026) were possibly associated with decreased VCM concentration. Multivariate analysis confirmed that urinary pH was an independent risk factor for VCM clearance (p = 0.029). VCM clearance in patients with a urine pH of 8 was significantly higher (p = 0.032) than in patients with a urinary pH of 5. As urinary pH increased in alkalinity, a greater decrease in VCM concentrations was observed. CONCLUSIONS: Elevation of urinary pH promotes the urinary excretion of VCM, likely by promoting the dissociation of the carboxyl group of VCM. Thus, in the clinical setting, urinary pH should be measured and considered when determining dosage, as it may affect the VCM blood concentration.

Enhanced antitumor effects of novel intracellular delivery of an active form of menaquinone-4, menahydroquinone-4, into hepatocellular carcinoma.

Reduced cellular uptake of menaquinone-4 (MK-4), a vitamin K2 homolog, in human hepatocellular carcinoma (HCC) limits its usefulness as a safe long-term antitumor agent for recurrent HCC and produces des-γ-carboxy prothrombin (DCP). We hypothesized that effective delivery of menahydroquinone-4 (MKH), the active form of MK-4 for γ-glutamyl carboxylation, into HCC cells is critical for regulating HCC growth, and may enable it to be applied as a safe antitumor agent. In this study, we verified this hypothesis using menahydroquinone-4 1,4-bis-N,N-dimethylglycinate hydrochloride (MKH-DMG), a prodrug of MKH, and demonstrated its effectiveness. Intracellular delivery of MKH and subsequent growth inhibition of PLC/PRF/5 and Hep3B (DCP-positive) and SK-Hep-1 (DCP-negative) cells after MKH-DMG administration were determined and compared with MK-4. The activity of MKH-DMG against tumor progression in the liver alongside DCP formation was determined in a spleen-liver metastasis mouse model. MKH-DMG exhibited greater intracellular delivery of MKH in vitro (AUC0-72 hour of MKH) and increased growth-inhibitory activity against both DCP-positive and DCP-negative HCC cell lines. The phenomena of MKH delivery into cells in parallel with simultaneous growth inhibition suggested that MKH is the active form for growth inhibition of HCC cells. Cell-cycle arrest was determined to be involved in the growth inhibition mechanisms of MKH-DMG. Furthermore, MKH-DMG showed significant inhibition of tumor progression in the liver, and a substantial decrease in plasma DCP levels in the spleen-liver metastasis mouse model. Our results suggest that MKH-DMG is a promising new candidate antitumor agent for safe long-term treatment of HCC.