The effect of potent CYP2D6 inhibition on the pharmacokinetics and safety of deutetrabenazine in healthy volunteers.

PURPOSE: Deutetrabenazine is a deuterated form of tetrabenazine with a confirmed lower rate of CYP2D6 metabolism of the active metabolites, α- and ß-HTBZ. In this study, we assessed the effect of paroxetine, a potent CYP2D6 inhibitor, on the pharmacokinetics and safety of deutetrabenazine and its metabolites. METHODS: In this open-label sequential drug-drug-interaction study, 24 healthy adults who were CYP2D6 extensive or intermediate metabolizers received a single deutetrabenazine 22.5-mg oral dose on days 1 and 11 and a single paroxetine 20-mg oral daily dose on days 4-12. Pharmacokinetics of deutetrabenazine and its metabolites were assessed on days 1-4 and 11-14. Paroxetine trough concentrations were obtained pre-dose on days 9-13. Safety examinations occurred throughout the study. RESULTS: Paroxetine administered under steady-state conditions, increased exposure of the deuterated active metabolites, α-HTBZ (1.2-fold Cmax and 1.8-fold AUC0-∞) and ß-HTBZ (2.1-fold Cmax and 5.6-fold AUC0-∞), and correspondingly, 1.6-fold Cmax and threefold AUC0-∞ for total (α + ß)-HTBZ. Sixteen subjects reported 45 adverse events and most were mild. Headache was the most common AE reported 8 times by 7 subjects (5 following paroxetine alone; 2 following deutetrabenazine + paroxetine). CONCLUSIONS: Paroxetine-induced increases in exposure to the active deutetrabenazine metabolites were less than those previously reported for tetrabenazine, a finding expected to reduce the burden of drug interaction. In addition, single doses of 22.5 mg deutetrabenazine, when given alone or in the presence of steady-state paroxetine (20 mg daily), were safe.

Efficacy and safety study of arbaclofen placarbil in patients with spasticity due to spinal cord injury.

STUDY DESIGN: Randomized, double-blind, placebo-controlled, two-period crossover. OBJECTIVES: To evaluate the efficacy and safety of arbaclofen placarbil (AP) in patients with spasticity secondary to spinal cord injury (SCI). SETTING: United States and Canada. METHODS: Patients received extended-release AP tablets 10, 20 or 30 mg every 12 h in one of two AP/placebo sequences, with 26 days of each treatment. The primary analysis compared Ashworth scale assessments of muscle tone between AP and placebo for the muscle group with maximum baseline Ashworth score. Secondary endpoints included a patient-rated Severity of Spasticity Scale. RESULTS: In the primary analysis, AP significantly improved Ashworth scores compared with placebo over the dosing interval: least-squares mean reduction versus placebo was 0.60 for AP 20 mg (P=0.0059) and 0.88 for AP 30 mg (P=0.0007). The difference was significant for the pre-morning dose time point, 12 h after the prior evening dose, indicating that efficacy was maintained throughout the dosing interval. Treatment differences for AP 10 mg versus placebo were not significant. Severity of Spasticity ratings were significantly reduced for the combined 20/30-mg group versus placebo (P=0.018). No statistically significant differences between AP and placebo were observed for muscle strength. AP-related AEs were generally mild to moderate in intensity, and none led to early withdrawal or were serious. CONCLUSION: AP was well tolerated at all investigated dosages and, when administered at doses of 20 or 30 mg twice daily, was efficacious in reducing spasticity due to SCI.

Short-course therapy with amoxycillin-clarithromycin triple therapy for 10 days (ACT-10) eradicates Helicobacter pylori and heals duodenal ulcer. ACT-10 Study Group.

BACKGROUND: Whilst the role of Helicobacter pylori eradication in managing duodenal ulcers has been established, consensus regarding the ideal regimen has not been achieved. METHODS: Patients with H. pylori-positive active duodenal ulcer were randomly assigned to receive triple therapy with amoxycillin 1000 mg b.d. + clarithromycin 500 mg b.d. + omeprazole 20 mg daily for 10 days (ACT-10) or dual therapy with clarithromycin 500 mg t.d.s. + omeprazole 40 mg daily for 14 days (Dual). No additional acid suppression was provided following eradication therapy. Endoscopy, with biopsy for culture and histology, as well as 13C-urea breath testing (13C-UBT) were performed pre-treatment to assess H. pylori infection. H. pylori eradication was established at 4-6 weeks follow-up with culture (2 antral, 1 corpus biopsies), histology (2 antral biopsies), and 13C-UBT. Ulcer healing by endoscopy and change in clinical symptoms were also assessed at 4-6 weeks. RESULTS: Two hundred and sixty-seven (267) patients were randomized to ACT-10 (n = 137) or Dual therapy (n = 130). By per-protocol and intention-to-treat analyses, H. pylori eradication at 4-6 weeks follow-up was 91% (115/127) and 88% (120/136), respectively, for ACT-10 patients and 59% (68/115) and 55% (72/130), respectively, for Dual therapy patients (P < 0.001 for both analyses). Ulcer healing was high in both treatment groups: ACT-10, 93% (118/127) and 90% (122/136), respectively; and Dual therapy, 91% (104/114) and 85% (111/130), respectively. Pre-treatment resistance to clarithromycin was low (4%, 8/214) as compared to metronidazole resistance which was over 40%. Emergence of resistance to clarithromycin was observed in 2% of patients receiving ACT-10 and in 25% of those receiving Dual therapy. ACT-10 and Dual therapy patients experienced similar rates of drug-related adverse events (33% vs. 32%, respectively) and discontinuation from therapy due to an adverse event (1.5% vs. 5%, respectively). More than 90% of patients were compliant with each prescribed medication. CONCLUSION: In patients with active duodenal ulcer, a 10-day course of amoxycillin-clarithromycin-based triple therapy without additional acid suppression is highly effective in eradicating H. pylori and healing duodenal ulcer.

PCR-RFLP typing of ureC from Helicobacter pylori isolated in Argentina from gastric biopsies before and after treatment with clarithromycin.

A clinical trial was conducted in Argentina to determine the efficacy of clarithromycin plus lansoprazole for the treatment of Helicobacter pylori in duodenal ulcers and non-ulcer dyspepsia. PCR-RFLP was conducted on an 820-bp amplified product of the ureC gene of H. pylori to determine the genetic heterogeneity of 83 pretreatment and 21 post-treatment isolates. Twelve different restriction patterns were observed when digested with Sau 3A or Hha I, resulting in 40 different RFLP types. Comparison of isolates before treatment to after treatment showed that 20 of 20 patients had the same RFLP type. In addition, the presence of the cytotoxin-associated gene (cagA) and the vacuolating gene (vacA) were determined. All pretreatment isolates were positive for vacA whereas 75% of the pretreatment isolates were positive for cagA. The results of this study indicate that a high degree of heterogeneity exists among H. pylori and that infection is not limited to a small number of RFLP types.

Human and guinea pig immune responses to Legionella pneumophila protein antigens OmpS and Hsp60.

We studied the immune responses of guinea pigs and humans to two Legionella pneumophila antigens. Guinea pigs surviving a lethal intraperitoneal challenge dose of virulent L. pneumophila exhibited strong cutaneous delayed-type hypersensitivity (DTH) reactions to purified OmpS (28-kDa major outer membrane protein) and Hsp60 (heat shock protein or common antigen), while weak DTH reactions were noted for extracellular protease (major secretory protein [MSP] [ProA]) and no reaction was observed with an ovalbumin (OA) control. Lymphocyte proliferation responses (LPRs) were measured for peripheral blood and spleen lymphocytes from guinea pigs surviving sublethal and lethal challenge doses of L. pneumophila. Lymphocytes from uninfected animals showed no proliferation to Hsp60 or OmpS, while lymphocytes from sublethally and lethally challenged animals exhibited strong proliferative responses to Hsp60 and OmpS. Guinea pigs vaccinated with purified OmpS exhibited low antibody titers and strong DTH and LPRs to OmpS, whereas lymphocytes from animals vaccinated with Hsp60 exhibited weak DTH responses and high antibody titers to Hsp60. All guinea pigs immunized with OmpS survived experimental challenge with L. pneumophila (two of two in a pilot study and seven of seven in trial 2) versus zero of seven OA-immunized controls (P = 0.006 by Fisher's exact test). In three vaccine trials in which animals were vaccinated with Hsp60, only 1 guinea pig of 15 survived lethal challenge. Peripheral blood lymphocytes (PBLs) from humans with legionellosis showed stronger LPRs to OmpS than PBLs from humans with no history of legionellosis (P = 0.0002 by Mann-Whitney test). PBLs of humans surviving legionellosis exhibited a lower but highly significant proliferative response to Hsp60 (P < 0.0001 compared with controls by Mann-Whitney test). These studies indicate that OmpS and Hsp60 are important antigens associated with the development of protective cellular immunity. However, as determined in vaccine trial studies in the guinea pig model for legionellosis, the species-specific antigen OmpS proved much more effective than the genus-common Hsp60 antigen.

Azithromycin pharmacokinetics and intracellular concentrations in Legionella pneumophila-infected and uninfected guinea pigs and their alveolar macrophages.

Azithromycin pharmacokinetics in Legionella pneumophila-infected and uninfected guinea pigs were assessed by measuring the drug concentration in whole lungs or the drug content in bronchoalveolar lavage (BAL) fluid in separate experiments. Azithromycin concentrations were measured by using a bioassay. The mean azithromycin content in the BAL fluid of infected guinea pigs was higher than that in controls at 10 h (0.87 versus 0.39 microgram; P = 0.05), 24 h (1.10 versus 0.37 microgram; P = 0.003), and 48 h (1.21 versus 0.28 microgram; P = 0.05) after a single intraperitoneal injection of drug (15 mg/kg). The mean peak lung azithromycin concentration was higher in control animals than in infected animals (15.8 versus 13.4 micrograms/ml). The mean lung azithromycin concentration in infected animals was significantly higher than that in controls 48 h after dosing (12.7 versus 10.4 micrograms/g; P = 0.04). There were no significant differences between infected and uninfected animals in serum azithromycin levels. Complementary experiments assessed intracellular/extracellular concentration ratios of azithromycin and erythromycin in L. pneumophila-infected and control guinea pig alveolar macrophages. Azithromycin was highly concentrated in alveolar macrophages, and the intracellular/extracellular concentration ratios for infected cells were significantly higher (P < 0.0001) than those observed in controls after 4 h (127 versus 119), 24 h (481 versus 361), and 48 h (582 versus 520) of incubation. Erythromycin was also preferentially concentrated in infected cells (P < 0.0001). AZ intracellular concentrations were at least fivefold higher than those measured for erythromycin, and this differential increased with incubation time. Thus, azithromycin recovery from BAL fluid, and from guinea pig lungs at the 48-h time point, was higher in the presence of experimental Legionnaires' disease. This likely results from recruitment of phagocytes, including macrophages, that have an enhanced capacity to highly concentrate the drug.

Possible psychometric problems in a test for selective deficits of conceptualization.

We administered a modified version of the test of Semenza, Denes, Lucchese, and Bisiacchi (Brain and Language, 10, 243-248 (1980)) for selective deficits in conceptualization to a group of normals and psychiatric patients. Analysis of the results obtained with the normal sample revealed several psychometric problems. The two components of the test (one for thematic and one for class relationships) each had poor internal consistency and were significantly different from each other on a measure of discriminating power. It is not clear if our results are related to difficulty in applying the test to an English-speaking population or reflect inherent psychometric problems.