Analysis of Atypical Antipsychotics-Induced Adverse Events Related to Diabetes Mellitus in Patients With Dementia Using the Japanese Adverse Drug Event Report Database.

BACKGROUND: Patients with dementia are prescribed low-dose atypical antipsychotics (AAPs) to treat psycho-behavioral symptoms. Although AAPs are known to cause diabetes mellitus-related adverse events (DMAEs), information regarding AAPs-induced DMAEs experienced by patients with dementia is lacking. OBJECTIVE: To use the Japan Adverse Drug Event Report (JADER) database to assess the onset tendencies and patterns of DMAEs attributable to AAPs prescribed to patients with dementia. METHODS: We performed an analysis using dementia cases from the JADER database that were registered from April 2004 to December 2022. Data in the JADER database are completely anonymized; thus, we did not require institutional review board approval for using the JADER database in our study. The reporting odds ratio and proportional reporting ratio (PRR) were used to assess the onset tendencies of DMAEs with AAPs. In addition, Weibull shape parameters were used to assess the patterns of DMAEs that occur with the use of AAPs. RESULTS: We identified AAPs associated with DMAEs. In particular, low doses of quetiapine showed the potential to induce DMAEs. An analysis of the onset of DMAEs showed the early failure patterns for AAPs (median onset = 38 days). CONCLUSION AND RELEVANCE: The AAPs may cause DMAEs in patients with dementia. Low doses of quetiapine may induce DMAEs. Health care workers should focus on the development of DMAEs during the early administration period of AAPs. These results may assist with the safe management of patients with dementia who use AAPs.

A Previously Unknown Drug-Drug Interaction Is Suspected in Delayed Elimination of Plasma Methotrexate in High-Dose Methotrexate Therapy.

Background: High-dose methotrexate (HD-MTX) therapy is widely implemented for leukemia, osteosarcoma, and lymphoma. Although various measures have been taken to avoid toxicity from high serum MTX concentrations, there are many cases of delayed elimination of MTX. Objective: We suspected that delayed elimination of serum MTX was caused by unknown interactions between MTX and concomitant drugs. Methods: Concerning concomitant drugs in the case of delayed elimination of MTX, we performed screening tests in 35 patients who had undergone HD-MTX therapy. We then investigated the risk factors for delayed MTX elimination in 94 patients with leukemia, lymphoma, or osteosarcoma retrospectively. Results: The percentages of concomitant use of Stronger Neo-Minophagen C (SNMC), a glycyrrhizin preparation, and vincristine were higher in the delayed group. The percentage of delayed MTX elimination in patients receiving HD-MTX therapy was 41%. Multiple logistic regression analysis revealed that the concomitant use of SNMC solely was a significant risk factor for delayed MTX (odds ratio = 12.20; 95% CI = 1.06-139.84). Conclusion and Relevance: Concomitant use of SNMC was shown to be related to delayed elimination of serum MTX, and our results suggested a previously unknown drug-drug interaction between MTX and SNMC.

Pharmacokinetics and tissue distribution of 3,4-diaminopyridine in rats.

Lambert-Eaton myasthenic syndrome (LEMS) is characterized by muscle weakness, amyotrophy, easy fatigability, and depressed tendon reflexes. 3,4-Diaminopyridine (3,4-DAP) is the recommended therapy for the treatment of LEMS. However, estimations of 3,4-DAP pharmacokinetics in human and animals, such as rats, are rarely reported because 3,4-DAP is an orphan drug for the treatment of a very rare disease (LEMS). In particular, little is known about its tissue distribution. Therefore, the pharmacokinetics of 3,4-DAP were studied, with particular focus on tissue distribution, in rats. After intravenous administration of 3,4-DAP to rats, the half-life of 3,4-DAP was 15.9 ± 3.9 min and the volume of distribution at steady-state was 2.8 ± 0.7 L/kg. The tissue-to-plasma partition coefficient (Kp) was high in the kidney, heart, and muscle. In addition, with increased steady state plasma concentration (Css), a tendency toward increased Kp was found in most tissues. In the muscle, a likely target region of 3,4-DAP in LEMS patients, the Kp was higher than in the plasma. Furthermore, more than 68% of 3,4-DAP was distributed to the muscle as determined by the ratio of 3,4-DAP distribution calculated from the apparent volumes of distribution. Hence, 3,4-DAP may provide for more effective and long-lasting effects.

Change in pharmacokinetics of mycophenolic acid as a function of age in rats and effect of coadministered amoxicillin/clavulanate.

Changes of mycophenolic acid (MPA) pharmacokinetics with aging were investigated in rats. We also compared the effect of concomitant amoxicillin/clavulanate combination (CVA/AMPC) on the pharmacokinetics of MPA in 4-week-old and 12-week-old rats (the package insert of CVA/AMPC warns of possible interaction with MPA). Four-week-old rats showed a 1.4-fold higher total body clearance of MPA and a lower volume of distribution of MPA (65%), compared to the values in 12-week-old rats. However, the difference in MPA pharmacokinetics disappeared when enterohepatic circulation was eliminated by bile duct cannulation (BDC). Concomitant CVA/AMPC significantly reduced plasma MPA concentration in intact rats of both age groups, and the age-dependent difference of MPA pharmacokinetics was no longer apparent. The effect of CVA/AMPC was not seen in rats that had undergone BDC, suggesting that the drug-drug interaction can be attributed to inhibition of enterohepatic circulation by CVA/AMPC. These results indicate that the aging-related alteration of MPA pharmacokinetics is a consequence of immature enterohepatic circulation in 4-week-old rats. Higher doses of MPA may be necessary in juveniles.

Diabetes Mellitus, Elevated Hemoglobin A1c, and Glycated Albumin Are Associated with the Presence of All-Cause Dementia and Alzheimer's Disease: The JPSC-AD Study.

BACKGROUND: Glucose dysmetabolism is an important risk factor for dementia. OBJECTIVE: We investigated the associations of diabetes mellitus, the levels of glycemic measures, and insulin resistance and secretion measures with dementia and its subtypes in a cross-sectional study. METHODS: In this study, 10,214 community-dwelling participants were enrolled. Hemoglobin A1c (HbA1c), the homeostasis model assessment (HOMA) for insulin resistance (HOMA-IR), the HOMA of percent ß-cell function (HOMA-ß), and the glycated albumin (GA) was evaluated. The associations of each measure with Alzheimer's disease (AD) and vascular dementia (VaD) were investigated. RESULTS: The multivariable-adjusted odds ratios (ORs) of AD were significantly higher in participants with diabetes mellitus than in those without diabetes (1.46 [95% CI: 1.08-1.97]). Higher HbA1c levels were significantly associated with AD at diabetes (≥6.5%) and even at prediabetes (5.7 %-6.4 %) levels; multivariable-adjusted ORs for AD in participants at the diabetes level were 1.72 (95% CI: 1.19-2.49), and those in participants at the prediabetes level were 1.30 (95% CI: 1.00-1.68), compared with those in normal participants. Moreover, higher GA levels were associated with AD. No associations were observed between the diabetic status or the levels of glycemic measures and VaD. In addition, no significant relationships were observed between insulin resistance and secretion measurements and AD and VaD. CONCLUSION: Our findings indicate that diabetes mellitus and hyperglycemia are significantly associated with AD, even in individuals at the prediabetes level.

Preventive effect of geniposide on metabolic disease status in spontaneously obese type 2 diabetic mice and free fatty acid-treated HepG2 cells.

Accumulation of visceral fat induces various symptoms of metabolic syndrome such as insulin resistance and abnormal glucose/lipid metabolism and eventually leads to the onset of ischemic cerebrovascular diseases. Geniposide, which is iridoid glycoside from the fruit of Gardenia jasminoides ELLIS, is recognized as being useful against hyperlipidemia and fatty liver. In order to clarify the effect of geniposide on metabolic disease-based visceral fat accumulation and the relevant molecular mechanism, experiments were performed in spontaneously obese Type 2 diabetic TSOD mice and the free fatty acid-treated HepG2 cells. In the TSOD mice, geniposide showed suppression of body weight and visceral fat accumulation, alleviation of abnormal lipid metabolism and suppression of intrahepatic lipid accumulation. In addition, geniposide alleviated abnormal glucose tolerance and hyperinsulinemia, suggesting that geniposide has an insulin resistance-alleviating effect. Next, in order to investigate the direct effect of geniposide on the liver, the effect on the free fatty acid-treated HepG2 fatty liver model was investigated using genipin, which is the aglycone portion of geniposide. Genipin suppressed the intracellular lipid accumulation caused by the free fatty acid treatment and also significantly increased the intracellular expression of a fatty acid oxidation-related gene (peroxisomal proliferator-activated receptor: PPARα). From these results, it was confirmed that geniposide has an anti-obesity effect, an insulin resistance-alleviating effect and an abnormal lipid metabolism-alleviating effect, and the metabolite genipin shows a direct effect on the liver, inducing expression of a lipid metabolism-related gene as one of its molecular mechanisms.

[Investigation for relation of gustatory and olfactory impairment in patients receiving cancer chemotherapy].

Because it is considered that there is a close connection between gustation and olfactation, and that a decline in the function of either sensation influences the other one, it would be useful to clarify the relation between gustatory and olfactory disorders in patients receiving cancer chemotherapy. Therefore, we investigated the frequency of gustatory and olfactory disorders in patients administered anticancer drugs at the Division of Outpatient Chemotherapy of Kanazawa University. Among 136 patients who consented to participate in the investigation, 75 patients (55%) complained of a gustatory disorder, and 26 patients (19%) complained of an olfactory disorder. The occurrences of olfactory disorder were significantly greater in patients who had gustatory disorder than in patients who did not. The expression frequency of gustatory disorders was significantly higher among those taking docetaxel (85%) when compared with patients on other regimens. Although not statistically significant, the incidence of olfactory disorder was higher in patients taking docetaxel (31%), irinotecan+l-leucovorin (l-LV)+5-fluorouracil (5-FU) (31%), l-oxaliplatin+l-LV+5-FU (28%), trastuzumab (23%), and weekly paclitaxel (22%). Medical staff should recognize that olfactory disorders are similar to gustatory disorders, as they both have adverse reactions induced by anticancer drugs.

[Factors Associated with Self-reported Medication Adherence in Japanese Community-dwelling Elderly Individuals: The Nakajima Study].

Medication non-adherence in the elderly population is a major problem, preventing them from obtaining optimal therapeutic effects. Identifying the factors affecting medication adherence is crucial for improving and maintaining health among the elderly population and enhance healthcare economy. The purpose of this study was to examine the prevalence of self-reported medication adherence, and identify the associated factors and the influence of health-related quality of life (HRQOL) in the Japanese community-dwelling elderly population. This cross-sectional study was part of the Nakajima study and targeted inhabitants aged ≥60 years who underwent health examinations in 2017. Data regarding medication adherence were acquired through interviews and self-administered questionnaires. Medication adherence were assessed using a visual analog scale, and HRQOL was assessed by EuroQol five-dimensional questionnaire with 3 levels. Among the 455 participants, low and high medication adherence were seen in 9.7% and 66.2% of the participants, respectively (visual analog scores <80% and ≥95%, respectively). Medication adherence was significantly lower in participants taking medications ≥3 times daily than in those taking medications once or twice daily; a regimen involving drug administration ≥3 times daily had significantly lower odds of medication adherence. The use of a drug profile book and HRQOL had significant positive association with medication adherence. Our results suggest that low dosing frequency and using a drug profile book was positively associated with medication adherence among elderly persons, which in turn could enhance their QOL.

Effects of functional variants of vitamin C transporter genes on apolipoprotein E E4-associated risk of cognitive decline: The Nakajima study.

Apolipoprotein E E4 (APOE4) is a risk factor for cognitive decline. A high blood vitamin C (VC) level reduces APOE4-associated risk of developing cognitive decline in women. In the present study, we aimed to examine the effects of functional variants of VC transporter genes expressed in the brain (SLC2A1, SLC2A3, and SLC23A2) on APOE4-associated risk of developing cognitive decline. This case-control study involved 393 Japanese subjects: 252 cognitively normal and 141 cognitively impaired individuals (87 mild cognitive impairment and 54 dementia). Database searches revealed that rs1279683 of SLC23A2, and rs710218 and rs841851 of SLC2A1 are functional variants that are significantly associated with the altered expression of the respective genes and genotyped as three single nucleotide variants (SNVs). When stratified by SNV genotype, we found a significant association between APOE4 and cognitive decline in minor allele carriers of rs1279683 (odds ratio [OR] 2.02, 95% CI, 1.05-3.87, p = 0.035) but not in the homozygote carriers of the major allele. Significant associations between APOE4 and cognitive decline were also observed in participants with major allele homozygotes of rs710218 (OR 2.35, 95% CI, 1.05-5.23, p = 0.037) and rs841851 (OR 3.2, 95% CI, 1.58-6.46, p = 0.0012), but not in minor allele carriers of the respective SNVs. In contrast, the three functional SNVs showed no significant effect on cognitive decline. Our results imply that functional SNVs of VC transporter genes can affect APOE4-associated risk of developing cognitive decline via altered VC levels in the brain.

Evaluation of selective competitive binding of basic drugs to alpha1-acid glycoprotein variants.

We examined the binding of various basic drugs to the F(1)S and A genetic variants of alpha(1)-acid glycoprotein (AGP), which were isolated from native human commercial AGP (total AGP) by chromatography on an immobilized copper(II) affinity adsorbent. The values of the dissociation constant (K(d)) of some basic drugs with the F(1)S variant in equilibrium dialysis differed characteristically from those with the A variant. The selective binding to these variants was evaluated by measuring the displacement ratio of dicumarol bound to the F(1)S variant or that of acridine orange bound to the A variant, using circular dichroism spectroscopy. There was reasonably good agreement between the K(d) values and displacement ratios. There was a characteristic difference between the values of inhibition constant (K(i)) of basic drugs towards dipyridamole binding to F(1)S and towards disopyramide binding to A in total AGP. We found that the K(i) values for dipyridamole binding were well correlated with the K(d) values for the F(1)S variant, whereas those for disopyramide binding were well correlated with the K(d) values for the A variant. In conclusion, the higher the affinity of basic drugs for AGP, the more they inhibit the binding of other basic drugs, and further, the inhibitory potency depends on the selectivity of binding to the AGP variants.

Effect of betamethasone phosphate loaded polymeric nanoparticles on a murine asthma model.

Although inhaled steroids are the treatment of first choice to control asthma, administration of systemic steroids is required for treatment of asthmatic exacerbation and intractable asthma. To improve efficacy and reduce side effects, we examine the effects of betamethasone disodium phosphate (BP) encapsulated in biocompatible, biodegradable blended nanoparticles (stealth nanosteroids) on a murine model of asthma. These stealth nanosteroids were found to accumulate at the site of airway inflammation and exhibit anti-inflammatory activity. Significant decreases in BALF eosinophil number were maintained for 7 days with a single injection of nanosteroids containing 40 microg BP. Airway responsiveness was also attenuated by the injection of stealth nanosteroids. A single injection of 40 microg of free BP and 8 microg of free BP once daily for 5 days did not show any significant effects. We conclude that stealth nanosteroids achieve prolonged and higher benefits at the site of airway inflammation compared to free steroids.

[Improvement of epirubicin-induced phlebitis to switch from liquid preparation to lyophilized formulation].

Adjuvant chemotherapy containing epirubicin is commonly used to treat patients with pre- or post-operative breast cancer. It is known that the epirubicin(FarmorubicinRTU)preparation often caused phlebitis, whereas dexamethasone has been used to prevent that reaction. We examined whether the lyophilized formulation of epirubicin(Farmorubicin)can reduces the incidence of phlebitis compared with the preparation. All infusions were administered through a peripheral vein. Adverse drug reaction including phlebitis was evaluated after each infusion and at the subsequent visit to four or six cycles. Sixty-two patients were given the preparation and 35 the lyophilized formulation. Epirubicininduced phlebitis was observed in 45.7% of patients given the preparation and in 48.4% of those given the lyophilized formulation. There was no statistically significant difference between the two groups(p=0.41). However, the incidence of severe phlebitis requiring treatment with steroid ointment was significantly increased among patients treated with the preparation(27.4% vs 9.7%, p<0.05, respectively). There was no significant difference in the incidence of adverse drug reactions other than severe phlebitis between the two groups. In this study, lyophilized formulations of epirubicin significantly reduced the incidence of severe phlebitis compared with that among patients receiving the preparation. Using lyophilized formulations of epirubicin should be considered to prevent a reduction in QOL with epirubicin-induced phlebitis in patients with breast cancer.

Risk factors for oxaliplatin-induced vascular pain in patients with colorectal cancer and comparison of the efficacy of preventive methods.

BACKGROUND: Vascular pain is a common adverse drug reaction in colorectal cancer patients receiving peripheral venous administration of oxaliplatin. The aim of this work was to identify risk factors for vascular pain, and to examine whether currently used treatments reduce its incidence. METHODS: We conducted a multicenter retrospective study in Japanese colorectal cancer patients receiving peripheral venous administration of oxaliplatin. The effects of various treatments (administration of analgesics, addition of dexamethasone to the infusion solution for pH adjustment, dilution of the infusion solution, or use of hot gel for warming the injection site) on the incidence of vascular pain were assessed. Risk factors for vascular pain were identified by multiple logistic regression analysis. RESULTS: One hundred and ninety patients who had received an oxaliplatin-containing regimen via a peripheral venous route were analyzed. None of the preventive methods examined significantly reduced the incidence of vascular pain. BMI (BMI < 22), clinical stage (I-III) and oxaliplatin dosage (130 mg/m2 versus dose reduction) were identified as independent risk factors for development of vascular pain. The incidence of oxaliplatin-induced vascular pain was significantly higher in patients who had two or more risk factors. CONCLUSIONS: BMI, clinical stage and oxaliplatin dosage were identified as independent predictive markers for oxaliplatin-induced vascular pain. Existing treatments for vascular pain are not effective in reducing its incidence.

Circadian rhythm of cytochrome P4502E1 and its effect on disposition kinetics of chlorzoxazone in rats.

The aim of this report is to study the circadian rhythm of cytochrome P4502E1 (CYP2E1) and its effect on the disposition kinetics of chlorzoxazone in male Wistar rats. The rats were housed under a 12-h light/dark cycle (lights from 9:00 to 21:00) with food and water ad libitum for 3 months. It was found that the expression of microsomal CYP2E1 mRNA in the liver during the dark phase was significantly lower than during the light phase, whereas the content of CYP2E1 protein and its hydroxylation activity were significantly higher. Therefore, chlorzoxazone 20 mg/kg was intravenously administered at 12:00 (light phase group) or 24:00 (dark phase group) to determine the effect on the disposition kinetics. The value of the area under the plasma concentration-time curve from 0 to 8 h (AUC(0-8 h)) of chlorzoxazone showed no significant difference between the two groups. However, the value of chlorzoxazone half-life in plasma of the light phase group was significant longer than the dark phase group. The AUC(0-8 h) of 6-hydroxychlorzoxazone, a metabolite formed from chlorzoxazone mainly by CYP2E1, was significantly higher in the dark phase than in the light phase. In conclusion, microsomal CYP2E1 shows a substantial circadian variation in rats, and this was associated with a decrease of chlorzoxazone half life, and an increase of 6-hydroxychlorzoxazone production. Therefore, the temporal variations of therapeutic response and toxicological effects may have to be taken into consideration for other xenobiotics that are predominantly metabolized by CYP2E1, particularly those with a short half-life.

Involvement of alpha1-acid glycoprotein in inter-individual variation of disposition kinetics of ropivacaine following epidural infusion in off-pump coronary artery bypass grafting.

The influence of drug interaction and protein variants on the binding disposition of ropivacaine to alpha1-acid glycoprotein (AGP) was examined. The subjects were five patients who received epidural infusion of ropivacaine for 24-54 h in off-pump coronary artery bypass grafting followed by drug combination therapy, and 10 healthy volunteers. The post-operation plasma albumin concentration showed little overall change, while the AGP concentration in the five patients decreased for 6 h, then increased gradually to about 3-times the initial value by 54 h. The unbound fraction in plasma (fu) of ropivacaine gradually decreased as the AGP concentration increased, but there was large inter-individual variation among the five patients. In contrast, there was a good correlation between the fu value and AGP concentration when ropivacaine was added to blood samples from the 10 healthy volunteers. Among the volunteers, eight showed F1S variants and two showed F1 variant without S variant of AGP. The fu value of ropivacaine did not differ between these two groups. However, when ropivacaine was added in combination with dipyridamole, the fu values of ropivacaine in blood from volunteers with F1S variants were greater than those in blood from volunteers without S variant. In the case of co-administration of disopyramide or lidocaine, there was no such difference. Among the patients, one showed F1S variants and four showed F1 variant without S variant. The results indicate that variability in the side-effects of therapy with ropivacaine alone is caused by the change of the unbound concentration upon changes in the AGP concentration. However, in combination therapy, it is also important to consider the AGP variant-dependence of the inhibitory effect of concomitantly administered drugs.

Improvement of Clinical Skills through Pharmaceutical Education and Clinical Research.

Professors and teaching staff in the field of pharmaceutical sciences should devote themselves to staying abreast of relevant education and research. Similarly those in clinical pharmacies should contribute to the advancement of pharmaceutical research and the development of next generation pharmacists and pharmaceuticals. It is thought that those who work in clinical pharmacies should improve their own skills and expertise in problem-finding and -solving, i.e., "clinical skills". They should be keen to learn new standard treatments based on the latest drug information, and should try to be in a position where collecting clinical information is readily possible. In the case of pharmacists in hospitals and pharmacies, they are able to aim at improving their clinical skills simply through performing their pharmaceutical duties. On the other hand, when a pharmaceutical educator aims to improve clinical skills at a level comparable to those of clinical pharmacists, it is necessary to devote or set aside considerable time for pharmacist duties, in addition to teaching, which may result in a shortage of time for hands-on clinical practice and/or in a decline in the quality of education and research. This could be a nightmare for teaching staff in clinical pharmacy who aim to take part in such activities. Nonetheless, I believe that teaching staff in the clinical pharmacy area could improve his/her clinical skills through actively engaging in education and research. In this review, I would like to introduce topics on such possibilities from my own experiences.

Co-administration of dexamethasone increases severity and accelerates onset day of neutropenia in bladder cancer patients on methotrexate, vinblastine, adriamycin and cisplatin chemotherapy: a retrospective cohort study.

BACKGROUND: Bladder cancer patients receiving methotrexate, vinblastine, adriamycin and cisplatin (MVAC) chemotherapy are co-administered with dexamethasone as an anti-emetic. We examined whether or not dexamethasone affects the severity and onset day of MVAC-induced severe neutropenia. METHODS: This was a retrospective study of bladder cancer patients treated with MVAC chemotherapy with or without dexamethasone as an antiemetic at Kanazawa University Hospital during January 2005 - December 2009. Patients were categorized into three groups; no dexamethasone use (Dex (-)), dexamethasone on day 2 (Dex 1 day), and dexamethasone on days 2, 3 and 4 (Dex multiday). We evaluated the incidence of grade 3/4 neutropenia and the day of onset of first severe neutropenic episode during the first course of MVAC chemotherapy. Logistic regression was used to investigate whether co-administration of dexamethasone was a risk factor for severe neutropenia. RESULTS: Episodes of grade 3/4 neutropenia occurred in 3 out of 6 (50.0%), 11 out of 12 (91.7%) and 6 out of 6 (100%) patients in the Dex (-), Dex 1 day, and Dex multiday groups, respectively. The appearance day of first severe neutropenia in the Dex multiday group (13.2 ± 1.0) was significantly accelerated compared to the Dex (-) group (17.7 ± 2.1). Univariate logistic regression analysis revealed that dexamethasone is a risk factor for severe neutropenia (OR 17.0; 95%CI: 1.3-223.1). CONCLUSIONS: Co-administration of dexamethasone for anti-emesis brings forward the first appearance of neutropenia, and increases the severity of neutropenia, in bladder cancer patients receiving MVAC chemotherapy.

Site-dependent contributions of P-glycoprotein and CYP3A to cyclosporin A absorption, and effect of dexamethasone in small intestine of mice.

We examined whether the oral bioavailability of cyclosporin A is controlled primarily by P-glycoprotein (P-gp) or CYP3A in the small intestine. In situ loop method was used to evaluate the uptake of cyclosporin A (40nmol) at the upper and lower intestine of wild-type and mdr1a/1b knockout mice treated or not treated with dexamethasone (75mg/kg/day, 7 days, i.p.). Expression of CYP3A mRNA in the control group was higher in the upper than the lower intestine, while that of the multidrug resistance-1a (mdr1a) mRNA was in the opposite order. Dexamethasone administration potently induced CYP3A and mdr1a mRNAs in the lower and upper intestine, respectively. At 45min after cyclosporin A administration into an upper intestinal loop of the control group of wild-type mice, the ratio of residual cyclosporin A to dose did not differ significantly from that of mdr1a/1b knockout mice, whereas in dexamethasone-treated wild-type mice, the residual ratio was increased significantly. The ratio of the cyclosporin A metabolite M17 to cyclosporin A in portal venous blood at an upper intestinal loop of mdr1a/1b knockout mice was much higher than that a lower intestinal loop. The M17/cyclosporin A ratio of portal venous blood at a lower intestinal loop in mdr1a/1b knockout mice was increased significantly by dexamethasone treatment. These results suggest that, under physiological conditions, the oral bioavailability of cyclosporin A is mainly controlled by CYP3A in the upper intestine, rather than liver, but when P-gp is induced by steroid, the intestinal absorption of cyclosporin A may be inhibited.

Cremophor EL releases cyclosporin A adsorbed on blood cells and blood vessels, and increases apparent plasma concentration of cyclosporin A.

We examined the influence of cremophor EL (crEL) on the disposition kinetics of CyA in rats. A dose of 10mg/kg of CyA in a volume of 750 microL containing 4.3, 16 or 30% concentration of crEL was intravenously administered over 1 min to rats. The values of distribution volume at the steady-state (Vd(ss)) and total clearance (CL(tot)) of CyA in the presence of increasing amounts of crEL were decreased to about 1/3-1/5 of those with 4.3% crEL, in a crEL concentration-dependent manner. The values of blood to plasma concentration ratio (RBP) and the apparent tissue to plasma concentration ratio (K(p,app)) of CyA with 30% crEL were both only about 1/2 of those of CyA with 4.3% crEL. Next, rats were intravenously given 30% crEL solution at 30 min after an intravenous administration of CyA (10 mg/kg) with 4.3% crEL. Subsequently, the blood and plasma concentrations of CyA rose significantly to 2.4 and 4.7 times those seen when i.v. 30% crEL was not given, respectively. In an in vitro study, we found that the uptake of CyA by red blood cells is inhibited by crEL, and that CyA adsorbed on the inner surface of blood vessels after the administration of CyA is released by crEL. The disposition kinetics of CyA is altered by i.v. administration in combination with the surfactant vehicle crEL, in a crEL concentration-dependent manner.

Modulation of mdr1a and CYP3A gene expression in the intestine and liver as possible cause of changes in the cyclosporin A disposition kinetics by dexamethasone.

We investigated the effect of dexamethasone (DEX) on the disposition kinetics of cyclosporin A (CyA) and the mechanism of this drug interaction. Rats were treated with DEX (1 or 75mg/kg per day, i.p.) once a day for 1-7 days, and the blood concentration of CyA was measured after an i.v. or p.o. dose of CyA (10mg/kg) at 1.5hr after the last DEX treatment. In rats treated with a low dose of DEX (1mg/kg), the blood concentration of CyA after i.v. administration was unchanged compared with that of untreated rats, whereas the blood concentration after oral administration was significantly decreased, and this decrease was dependent on the duration of DEX administration. The total clearance (CL(tot)) of CyA was unchanged, but the bioavailability was significantly decreased to about one-third of that in DEX-untreated rats after 7 days of DEX treatment. At this time, the expression of mdr1a mRNA and P-gp in the liver and intestine was increased, whereas CYP3A2 was unaffected at both the mRNA and protein levels. In rats treated with a high dose of DEX (75mg/kg), the blood concentration of CyA was significantly decreased after both i.v. and p.o. administrations compared with those of untreated rats. The bioavailability of CyA was decreased, and the CL(tot) was significantly increased. The P-gp and CYP3A2 in the liver and intestine were increased at both the mRNA and protein levels. Our results indicate that the drug interaction between CyA and DEX is a consequence of modulation of P-gp and CYP3A2 gene expression by DEX, with differential dose-dependence.