An alternative sterility assessment for parenteral drug products using isothermal microcalorimetry.

AIMS: Production and release of injectable drug solutions are highly regulated since the administration of injectables bypasses natural body barriers. The sterility test is the last opportunity of product quality assessment. However, sterility is currently assessed by visual inspection (VI) that is time consuming and somewhat subjective. Therefore, we assessed isothermal microcalorimetry (IMC) as a replacement for the VI of the filtration based state-of-the-art sterility control. METHODS AND RESULTS: We used ATCC strains and house isolates to artificially contaminate frequently produced monoclonal antibodies (Avastin, Mabthera, Herceptin). After filtration, growth was assessed with IMC. Growth of all micro-organisms was reliably and reproducibly detected 4 days after inoculation, which was significantly faster than with VI. CONCLUSIONS: The reliability and the sensitivity of IMC have a large potential to improve sterility controls. Further evaluation of this alternative method is therefore highly recommended. SIGNIFICANCE AND IMPACT OF THE STUDY: Drug safety is of great concern for public health. Faster and safer drug production could be achieved using the technique described here. All the tests were performed with real manufactured drugs and complied with pharmaceutical standards. This suggests that drug sterility testing can be improved with potentially increased safety and cost reduction.

Acute calcineurin inhibitor overdose: analysis of cases reported to a national poison center between 1995 and 2011.

Transplant recipients and other patients requiring immunosuppression with calcineurin inhibitors or their household contacts may be exposed to overdose. This study investigated the circumstances, pharmacokinetics and outcomes of overdose with cyclosporine and tacrolimus reported to the Swiss Toxicological Information Centre between 1995 and 2011. Of 145,396 reports by healthcare professionals, 28 (0.02%) concerned enteral or parenteral overdose with these calcineurin inhibitors. Thirteen (46%) were iatrogenic errors, 12 (43%) were with suicidal intent and 3 (11%) were accidental. Iatrogenic overdoses usually involved noncapsule drug formulations. Acute enteral overdoses caused symptoms in a dose-dependent fashion but were generally well tolerated; the mean multiple of patient's usual dose was 20.8 ± 28.8 for symptomatic versus 4.4 ± 3.4 for asymptomatic cases (p = 0.037). The most common symptoms were nausea, headache, somnolence, confusion, hypertension and renal impairment. In contrast, acute intravenous overdoses were often poorly tolerated and resulted in one fatality due to cerebral edema after a cyclosporine overdose. Enteral decontamination measures were performed in six cases involving oral ingestion and appeared to reduce drug absorption, as shown by pharmacokinetic calculations. In the one case where it was used, pharmacoenhancement appeared to accelerate tacrolimus clearance after intravenous overdose.

Targeting immunoliposomes to EGFR-positive glioblastoma.

BACKGROUND: We assessed the capacity of epidermal growth factor receptor (EGFR)-targeted immunoliposomes to deliver cargo to brain tumor tissue in patients with relapsed glioblastoma harboring an EGFR amplification. We aimed to assess the tolerability and effectiveness of anti-EGFR immunoliposomes loaded with doxorubicin (anti-EGFR ILs-dox) in glioblastoma multiforme patients. PATIENTS AND METHODS: Patients with EGFR-amplified, relapsed glioblastoma were included in this phase I pharmacokinetic trial. Patients received up to four cycles of anti-EGFR ILs-dox. Twenty-four hours later, plasma and cerebrospinal fluid (CSF) samples were obtained. In addition, we also treated three patients with anti-EGFR ILs-dox before resection of their relapsed glioblastoma. Doxorubicin concentrations were measured in plasma, CSF, and tumor tissue. Safety and efficacy parameters were also obtained. RESULTS: There were no or negligible levels of doxorubicin found in the CSF demonstrating that anti-EGFR ILs-dox are not able to cross the blood-brain barrier (BBB). However, significant levels were detected in glioblastoma tissue 24 h after the application, indicating that the disruption of BBB integrity present in high-grade gliomas might enable liposome delivery into tumor tissue. No new safety issues were observed. The median progression-free survival was 1.5 months and the median overall survival was 8 months. One patient undergoing surgery had a very long remission suggesting that neoadjuvant administration may have a positive effect on outcome. CONCLUSIONS: We clearly demonstrate that anti-EGFR-immunoliposomes can be targeted to EGFR-amplified glioblastoma and cargo-in this case doxorubicin-can be delivered, although these immunoliposomes do not cross the intact BBB. (The GBM-LIPO trial was registered as NCT03603379).

Bile duct injury and use of cholangiography during laparoscopic cholecystectomy.

BACKGROUND: Bile duct injury (BDI) remains the most serious complication of laparoscopic cholecystectomy (LC). A Swiss database was used to identify risk factors for BDI and to assess the effect of intraoperative cholangiography (IOC). METHODS: Data for patients from 114 Swiss institutions who underwent LC for acute or chronic cholecystitis between 1995 and 2005 were used in univariable and logistic regression analyses. RESULTS: In total 31 838 patients, mean(s.d.) age 54·4(15·9) years, were analysed. The incidence of BDI was 0·3 per cent (101 patients), which did not change over time (P = 0·560). Univariable analysis revealed that male patients had a higher risk of BDI (0·5 per cent versus 0·2 per cent in female patients; P = 0·001), as did patients whose operation lasted at least 150 min (1·1 per cent versus 0·1 per cent for operating time of less than 150 min; P < 0·001). Logistic regression confirmed male sex (odds ratio (OR) 1·89, 95 per cent confidence interval 1·27 to 2·81) and prolonged surgery (OR 12·60, 10·87 to 23·81) as independent risk factors. Comparison of groups with and without intraoperative cholangiography showed no difference in the incidence of BDI (both 0·3 per cent; P = 0·755) and BDIs missed during surgery (10 versus 8 per cent; P = 0·737). CONCLUSION: Male sex and prolonged laparoscopic surgery are independent risk factors for BDI during LC. Frequent use of IOC does not seem to reduce BDI or the number of injuries missed during surgery.

Methotrexate area under the curve is an important outcome predictor in patients with primary CNS lymphoma: A pharmacokinetic-pharmacodynamic analysis from the IELSG no. 20 trial.

BACKGROUND: This analysis was initiated to define the predictive value of the area under the curve of high-dose methotrexate (AUC(HD-MTX)) in patients with primary central nervous system lymphoma (PCNSL). PATIENTS AND METHODS: We included 55 patients with PCNSL and available pharmacokinetic (PK) data from the International Extranodal Lymphoma Study Group (IELSG) no. 20 trial, randomised to HD-MTX (n=30) or HD-MTX and high-dose cytarabine (HD-AraC) (n=25). Individual AUC(HD-MTX) from population PK analysis was tested on drug toxicity and clinical outcome using multivariate logistic regression analysis and Cox hazards modelling. RESULTS: AUC(HD-MTX), the IELSG score and treatment group were significant predictors for treatment response (complete or partial) in the adjusted model. The AUC(HD-MTX) did not predict toxicity, with the exception of liver toxicity and neutropaenia. A high AUC(HD-MTX) was associated with better event-free survival (EFS) (P=0.01) and overall survival (OAS) (P=0.02). Both the AUC(HD-MTX) and the IELSG score were significant predictors of EFS and OAS in the adjusted model, with a hazard ratio of 0.82 and 0.73, respectively, per 100 micromol l(-1) h(-1) increase in AUC(HD-MTX). CONCLUSIONS: Individualised dosing of HD-MTX might have the potential to improve clinical outcome in patients with PCNSL, even when administered concurrently with HD-AraC. In the future, this could be carried out by using first-cycle PK modelling with determination of potential dose adaptations for later cycles using Bayesian analysis.

[Seizure and non-cardiogenic pulmonary edema after intoxication]. / 35-jährige Patientin mit generalisiertem Krampfanfall und nicht-kardiogenem Lungenödem nach Intoxikation.

We report a case of severe intoxication with extended-release verapamil. In addition to cardiovascular toxicities with hypotension, atrioventricular block and bradycardia, the patient suffered from grand-mal seizure and pulmonary edema 13 and 48 hours respectively, after ingestion of 4.8 g of extended-release verapamil. Adverse reactions after intoxications with extended-release tablets appear delayed with prolonged manifestation of symptoms. Early and repetitive administration of activated charcoal and antegrade whole bowel lavage are crucial, even in primary asymptomatic patients.

Endoscopic retroperitoneal neurectomy for chronic pain after groin surgery.

BACKGROUND: Chronic postoperative pain after inguinal surgery remains a difficult problem. The role of minimally invasive surgery in this complex setting is still unexplored. METHODS: Between January 1997 and January 2007, 34 men and five women with a mean(s.d.) age of 47(16) years underwent endoscopic retroperitoneal neurectomy (ERN) for chronic neuropathic groin pain due to genitofemoral nerve with or without ilioinguinal nerve entrapment. Follow-up data were obtained 1 and 12 months after surgery. RESULTS: At both timepoints after ERN, the severity of chronic postoperative groin pain at rest and during daily activities, and the rate of occupational disability, were significantly decreased in 27 of the 39 patients compared with preoperative values (all P < 0.001). CONCLUSION: ERN for chronic postoperative genitofemoral nerve entrapment neuropathy was successful in the majority of patients selected for the procedure. This minimally invasive approach allows simultaneous neurectomy of genitofemoral and ilioinguinal nerves.

Interaction with the hERG channel and cytotoxicity of amiodarone and amiodarone analogues.

BACKGROUND AND PURPOSE: Amiodarone (2-n-butyl-3-[3,5 diiodo-4-diethylaminoethoxybenzoyl]-benzofuran, B2-O-CH(2)CH(2)-N-diethyl) is an effective class III antiarrhythmic drug demonstrating potentially life-threatening organ toxicity. The principal aim of the study was to find amiodarone analogues that retained human ether-a-go-go-related protein (hERG) channel inhibition but with reduced cytotoxicity. EXPERIMENTAL APPROACH: We synthesized amiodarone analogues with or without a positively ionizable nitrogen in the phenolic side chain. The cytotoxic properties of the compounds were evaluated using HepG2 (a hepatocyte cell line) and A549 cells (a pneumocyte line). Interactions of all compounds with the hERG channel were measured using pharmacological and in silico methods. KEY RESULTS: Compared with amiodarone, which displayed only a weak cytotoxicity, the mono- and bis-desethylated metabolites, the further degraded alcohol (B2-O-CH(2)-CH(2)-OH), the corresponding acid (B2-O-CH(2)-COOH) and, finally, the newly synthesized B2-O-CH(2)-CH(2)-N-pyrrolidine were equally or more toxic. Conversely, structural analogues such as the B2-O-CH(2)-CH(2)-N-diisopropyl and the B2-O-CH(2)-CH(2)-N-piperidine were significantly less toxic than amiodarone. Cytotoxicity was associated with a drop in the mitochondrial membrane potential, suggesting mitochondrial involvement. Pharmacological and in silico investigations concerning the interactions of these compounds with the hERG channel revealed that compounds carrying a basic nitrogen in the side chain display a much higher affinity than those lacking such a group. Specifically, B2-O-CH(2)-CH(2)-N-piperidine and B2-O-CH(2)-CH(2)-N-pyrrolidine revealed a higher affinity towards hERG channels than amiodarone. CONCLUSIONS AND IMPLICATIONS: Amiodarone analogues with better hERG channel inhibition and cytotoxicity profiles than the parent compound have been identified, demonstrating that cytotoxicity and hERG channel interaction are mechanistically distinct and separable properties of the compounds.

Effect of temporal onsets of mechanical loading on bone formation inside a tissue engineering scaffold combined with cell therapy.

Several approaches to combine bone substitutes with biomolecules, cells or mechanical loading have been explored as an alternative to the limitation and risk-related bone auto- and allo-grafts. In particular, human bone progenitor cells seeded in porous poly(L-lactic acid)/tricalcium phosphate scaffolds have shown promising results. Furthermore, the application of mechanical loading has long been known to be a key player in the regulation of bone architecture and mechanical properties. Several in vivo studies have pointed out the importance of its temporal offset. When an early mechanical loading was applied a few days after scaffold implantation, it was ineffective on bone formation, whereas a delayed mechanical loading of several weeks was beneficial for bone tissue regeneration. No information is reported to date on the effectiveness of applying a mechanical loading in vivo on cell-seeded scaffold with respect to bone formation in a bone site. In our study, we were interested in human bone progenitor cells due to their low immunogenicity, sensitivity to mechanical loading and capacity to differentiate into osteogenic human bone progenitor cells. The latest capacity allowed us to test two different bone cell fates originating from the same cell type. Therefore, the general aim of this study was to assess the outcome on bone formation when human bone progenitor cells or pre-differentiated osteogenic human bone progenitor cells are combined with early and delayed mechanical loading inside bone tissue engineering scaffolds. Scaffolds without cells, named cell-free scaffold, were used as control. Surprisingly, we found that (1) the optimal solution for bone formation is the combination of cell-free scaffolds and delayed mechanical loading and that (2) the timing of the mechanical application is crucial and dependent on the cell type inside the implanted scaffolds.

Relationship between the coenzyme A and the carnitine pools in human skeletal muscle at rest and after exhaustive exercise under normoxic and acutely hypoxic conditions.

Skeletal muscle CoA and carnitine metabolism were investigated in six human volunteers at rest and after exhaustive exercise under normoxic and hypoxic conditions. In comparison to the values at rest, exhaustive exercise was associated with a three- to fourfold increase in the skeletal muscle lactate, and with a twofold increase in the acetyl-CoA content, both under normoxic and hypoxic conditions. Since exercise did not significantly affect the skeletal muscle CoA radical (CoASH), total acid-soluble, or total CoA contents, the increase in the acetyl-CoA content was at the expense of short-chain acyl-CoAs different from acetyl-CoA. With exhaustive exercise, the skeletal muscle acetylcarnitine and short-chain acylcarnitine contents increased by a factor of three to four both under normoxic and hypoxic conditions. In contrast to the CoA pool, these increases were associated with a decrease in the free carnitine content, whereas the total acid-soluble and total carnitine contents were not affected by exercise. After exhaustive exercise, the skeletal muscle acetyl-CoA/CoASH ratio showed a linear correlation with the corresponding acetylcarnitine/free carnitine ratio. The plasma short-chain acylcarnitine concentration increased by a factor of two to three during exercise, and was not significantly different from the values at rest 40 min after completion of exercise. Thus, the current studies illustrate the close interaction between the CoA and carnitine pools in the exercising human skeletal muscle, and they underscore the important role of carnitine in maintaining the muscular CoASH content during exhaustive exercise.

Increased hepatic mitochondrial capacity in rats with hydroxy-cobalamin[c-lactam]-induced methylmalonic aciduria.

Treatment of rats with the vitamin B12 analogue hydroxy-cobalamin[c-lactam] (HCCL) impairs methylmalonyl-CoA mutase function and leads to methylmalonic aciduria due to intracellular accumulation of propionyl and methylmalonyl-CoA. Since accumulation of these acyl-CoAs disrupts normal cellular regulation, the present investigation characterized metabolism in hepatocytes and liver mitochondria from rats treated subcutaneously with HCCL or saline (control) by osmotic minipump. Consistent with decreased methylmalonyl-CoA mutase activity, 14CO2 production from 1-14C-propionate (1 mM) was decreased by 76% and 82% after 2-3 wk and 5-6 wk of HCCL treatment, respectively. In contrast, after 5-6 wk of HCCL treatment, 14CO2 production from 1-14C-pyruvate (10 mM) and 1-14C-palmitate (0.8 mM) were increased by 45% and 49%, respectively. In isolated liver mitochondria, state 3 oxidation rates were unchanged or decreased, and activities of the mitochondrial enzymes, citrate synthetase, succinate dehydrogenase, carnitine palmitoyltransferase, and glutamate dehydrogenase (expressed per milligram mitochondrial protein) were unaffected by HCCL treatment. In contrast, activities of the same enzymes were significantly increased in both liver homogenate (expressed per gram liver) and isolated hepatocytes (expressed per 10(6) cells) from HCCL-treated rats. The mitochondrial protein per gram liver, calculated on the basis of the recovery of the mitochondrial enzymes, increased by 39% in 5-6 wk HCCL-treated rats. Activities of lactate dehydrogenase, catalase, cyanide-insensitive palmitoyl-CoA oxidation, and arylsulfatase A in liver were not affected by HCCL treatment. Hepatic levels of mitochondrial mRNAs were elevated up to 10-fold in HCCL-treated animals as assessed by Northern blot analysis. Thus, HCCL treatment is associated with enhanced mitochondrial oxidative capacity and an increased mitochondrial protein content per gram liver. Increased mitochondrial oxidative capacity may be a compensatory mechanism in response to the metabolic insult induced by HCCL administration.

Automated high throughput analysis of antiretroviral drugs in dried blood spots.

For therapeutic drug monitoring in remote settings, dried blood spots (DBS) are particularly advantageous, as blood sample collection and handling is uncomplicated. The aim of this study was to develop and validate an automated extraction method for the analysis of nevirapine, efavirenz and lopinavir in DBS samples. Automated extraction was performed with methanol : water (70 : 30 v/v), using a DBS-MS 500 autosampler coupled to a liquid chromatography tandem mass spectrometry system. The autosampler used digital images of each DBS to position the extraction head, sprayed 10 µl of internal standard onto each DBS and extracted a 4-mm disc (Ø) from the centre of each spot by unilateral flow using 25-µl extraction solvent. The analytes were baseline separated on a pentafluorophenyl column and analysed by using electrospray ionization with multiple reaction monitoring in positive polarity mode for nevirapine and lopinavir and in negative mode for efavirenz. The method was linear between 10 and 10 000 ng/ml for all analytes. Automated sample extraction resulted in consistent recoveries (nevirapine: 70 ± 6%, efavirenz: 63 ± 11% and lopinavir: 60 ± 10%) and matrix effects between different donors and concentration levels. Intra-day and inter-day accuracy and precision deviations were ≤15%. Manual and automated extractions of DBS samples collected within the framework of an adherence assessment study in rural Tanzania showed good agreements with deviations of less than 10%. Our study highlights that therapeutic drug monitoring samples obtained in the resource-constrained setting of rural Africa can be reliably determined by automated extraction of DBS. Overall, automatization improved method sensitivity and facilitates analysis of large sample numbers. Copyright © 2017 John Wiley & Sons, Ltd.

Erlotinib has comparable clinical efficacy to chemotherapy in pretreated patients with advanced non-small cell lung cancer (NSCLC): A propensity-adjusted, outcomes research-based study.

OBJECTIVES: Controversy exists about the integration of erlotinib in patients with EGFR wildtype, advanced NSCLC. MATERIALS AND METHODS: We included patients with advanced NSCLC receiving at least two lines of palliative systemic treatment between January 2005 and December 2014 and not harbouring targetable driver mutations. Primary study endpoint was overall survival (OS), secondary endpoint progression-free survival (PFS). We used Kaplan-Meier statistics, multivariate Cox regression and Propensity score or Inverse Probability Weights (IPW) matching to compare clinical outcome between patients receiving erlotinib in second or further line and those receiving chemotherapy only. The study had a power of 90% to detect a survival superiority of 30%. RESULTS: From a total of 827 patients, we excluded 171 patients with potentially curative treatment, 189 receiving treatment outside of our institute, 206 receiving no or only one line of systemic treatment, 6 with ALK translocations and 28 with EGFR mutations. From 227 patients in the final efficacy analysis, 125 patients received erlotinib in second (89 patients), third (28) or further-line (8), and 102 patients received chemotherapy only. Women and never smokers were significantly overrepresented in the erlotinib group. Both OS (hazard ratio (HR)=1.14, 95% CI 0.80-1.63, P=0.448) and PFS (HR=1.20, 95% CI 0.95-1.52, P=0.119) were similar in the erlotinib compared to the chemotherapy group using IPW-adjusted Cox regression analysis treating the use of erlotinib as a time-dependent covariate starting from second-line treatment and stratified for ECOG performance status and treatment line. ECOG performance status was the most powerful covariate to select patients for erlotinib treatment. CONCLUSION: The present study suggests erlotinib to have similar clinical efficacy compared to chemotherapy in patients with pretreated advanced NSCLC and no known molecular targetable alterations.

Alterations in mitochondrial function and morphology in chronic liver disease: pathogenesis and potential for therapeutic intervention.

Studies assessing mitochondrial function and structure in livers from humans or experimental animals with chronic liver disease, including liver cirrhosis, revealed a variety of alterations in comparison with normal subjects or control animals. Depending on the etiology of chronic liver disease, the function of the electron transport chain and/or ATP synthesis was found to be impaired, leading to decreased oxidative metabolism of various substrates and to impaired recovery of the hepatic energy state after a metabolic insult. Changes in mitochondrial structure include megamitochondria with reduced cristae, dilatation of mitochondrial cristae and crystalloid inclusions in the mitochondrial matrix. The most important strategies to maintain an adequate mitochondrial function per liver are mitochondrial proliferation and increases in the activity of critical enzymes or in the content of cofactors per mitochondrion. Possibilities to assess hepatic mitochondrial function and to treat mitochondrial dysfunction in patients with chronic liver disease are discussed.

Hepatic carbohydrate metabolism in rats after laparotomy and laparoscopy.

BACKGROUND: Portal venous and mesenteric blood flow are reduced by 40-60% in humans and animals during laparoscopic surgery compared to laparotomy. Little is known about whether these intraabdominal micro- and macrocirculatory changes are associated with alterations in the hepatic energy metabolism. METHODS: We operated on male Sprague-Dawley rats, performing either laparoscopy (CO2, 6 mmHg; n = 27) or laparotomy (n = 28), and compared the results with two control groups: intraperitoneal (i.p.) endotoxin administration (n = 28, positive control) and anesthesia only (n = 28, negative control). We investigated the impact of the two different surgical techniques on daily food intake, body weight gain, glycogen content in the liver, levels of blood glucose, and liver function tests (LFTs) on postoperative days 1, 2, 4, and 8. Local (hepatic) and systemic inflammatory responses (interleukin-6 and tumor necrosis factor-alpha) during the postoperative time course were also determined. Data were analyzed using the Kruskal-Wallis test or univariate analysis of variance. RESULTS: Body weight gain, food intake, liver and spleen weights, as well as LFTs [except aspartate aminotransferase (AST)] did not differ among the four groups. The significant increase in the AST level following laparoscopy compared to the anesthesia-only group was found on postoperative days 1 and 2; however, a similar difference was not detected after laparotomy or i.p. endotoxin injection. Laparoscopy showed no alterations in the hepatic glycogen stores compared to anesthesia only, whereas laparotomy and endotoxinemia significantly reduced the hepatic glycogen stores on postoperative days 2 and 4. The systemic postoperative inflammatory response did not differ between laparotomy and laparoscopy, but it was higher in both groups than in anesthesia only. In rats treated with endotoxin, the systemic inflammatory response was even higher than in the two surgical groups. The hepatic inflammatory response did not differ between the four groups. CONCLUSION: This study shows a significant postoperative decrease in the hepatic glycogen content after laparotomy and i.p. endotoxin injection but not after laparoscopy. Food intake and inflammatory response cannot explain this difference between the two surgical groups, which suggests that alterations in the postsurgical hormonal stress response are the most likely explanation for these findings.

Kinetics and dynamics of orally administered 18 beta-glycyrrhetinic acid in humans.

18 beta-Glycyrrhetinic acid (GRA) represents a major metabolite of glycyrrhizic acid (glycyrrhizin), an important constituent of licorice and licorice root, and is a potent inhibitor of 11 beta-hydroxysteroid dehydrogenase (11 beta OHSD). Different oral doses of GRA (500, 1000, or 1500 mg) were administered to healthy volunteers in order to study its kinetics and dynamics. In agreement with the lipophilic nature of GRA, with a biphasic decay of the plasma concentration-time curve at doses greater than 500 mg. The mean (+/-SEM) half-life of the second elimination phase was 11.5 +/- 1.2 h after 1000 mg GRA and 38.7 +/- 10.5 h after 1500 mg GRA (P < 0.05). The peak plasma concentration and the area under the plasma concentration-time curve (AUC) increased with increasing GRA doses. Urinary elimination of GRA and GRA glucuronides over 24 h was less than 1% of the dose administered. The dynamics of GRA were assessed by measuring the activity of the 11 beta OHSD in vivo, as reflected by the cortisol and cortisone concentrations in plasma. With increasing doses of GRA, the cortisone concentration declined, and the cortisol/cortisone ratio increased. Both peak plasma concentration and AUCs of GRA correlated with changes in the AUC values of cortisone. Based on the single dose kinetics, the kinetic/dynamic analysis of the data revealed that after multiple doses of 1.5. g GRA/day, the 11 beta OHSD might be constantly inhibited, whereas at daily doses of 500 mg or less, such an inhibition might occur only transiently.

Interaction between grapefruit juice and midazolam in humans.

OBJECTIVE: To investigate the effects of grapefruit juice on the pharmacokinetics and dynamics of midazolam. METHODS: Eight healthy male subjects participated in this open crossover study. Intravenous (5 mg) or oral (15 mg) midazolam was administered after pretreatment with water or grapefruit juice. We measured the pharmacokinetics and pharmacodynamics (reaction time, Digit Symbol Substitution Test [DSST], general impression judged by the investigators, and drug effect judged by the subjects) of midazolam and the pharmacokinetics of alpha-hydroxymidazolam. RESULTS: In comparison to water, pretreatment with grapefruit juice did not change the pharmacokinetics or pharmacodynamics of intravenous midazolam. After oral administration, pretreatment with grapefruit juice led to a 56% increase in peak plasma concentration (Cmax), a 79% increase in time to reach Cmax (tmax), and a 52% increase in the area under the plasma concentration-time curve (AUC) of midazolam, which was associated with an increase in the bioavailability from 24% +/- 3% (water) to 35% +/- 3% (Grapefruit juice; mean +/- SEM, p < 0.01) After oral administration of midazolam, pretreatment with grapefruit juice was associated with a 105% increase in tmax and with a 30% increase in the AUC of alpha-hydroxymidazolam. For oral midazolam, pretreatment with grapefruit juice led to significant increases in tmax for all dynamic parameters and in the AUC values for the reaction time and DSST, whereas the maximal dynamic effects remained unchanged. CONCLUSIONS: Pretreatment with grapefruit juice is associated with increased bioavailability and changes in the pharmacodynamics of midazolam that may be clinically important, particularly in patients with other causes for increased midazolam bioavailability such as advanced age, cirrhosis of the liver, and administration of other inhibitors of cytochrome P450.

Identification and tissue distribution of two differentially spliced variants of the rat carnitine transporter OCTN2.

In this paper we show that the only known Na(+) dependent transporter of carnitine in mammals, organic cation transporter number 2 (OCTN2), is subject to differential splicing. Cloning of OCTN2 in different rat tissues identified two splicing variants. We have developed a real time quantitative polymerase chain reaction method for quantification of these splice variants. Both splice variants could be detected in all tissues examined with a relative abundance of 0.1-1% of the full length transcript. We also draw attention to the previously described mutations in clinical examples of primary carnitine deficiency in humans where the described mutations appear to be those of a splicing or mis-splicing event.