Human pharmacology of intravenous lisdexamfetamine dimesylate: abuse liability in adult stimulant abusers

The objective of this study is to determine the safety, tolerability and abuse liability of single intravenous (i.v.) doses of lisdexamfetamine dimesylate (LDX) and immediate-release d-amphetamine sulphate in adult stimulant abusers compared with placebo. Adult substance abusers were enrolled in this phase I, randomized, single-centre, double-blind study. An initial cohort of three subjects was enrolled to assess safety followed by a primary cohort that consisted of nine subjects. Single i.v. doses of LDX (25 or 50 mg), immediate-release d-amphetamine sulphate (10 or 20 mg) or placebo were administered at a minimum of 48-h intervals in a single-dose, three-way crossover design. 20 mg of d-amphetamine showed significantly increased abuse-related liking scores compared with placebo (P < 0.05), whereas the liking effects of 50 mg LDX did not significantly differ from placebo. The mean C(max) of d-amphetamine was 38.9 +/- 8.1 and 105 +/- 91.4 ng/ml after the administration of 50 mg LDX and 20 mg d-amphetamine respectively. The mean T(max) of d-amphetamine was 2.51 h after the administration of 50 mg LDX and 0.82 h after the administration of 20 mg d-amphetamine. LDX was well tolerated in this population. In contrast to d-amphetamine, LDX administered intravenously did not produce significant subjective abuse-related liking scores at assessed doses.

Abuse liability and safety of oral lisdexamfetamine dimesylate in individuals with a history of stimulant abuse

Lisdexamfetamine dimesylate (LDX) is the first prodrug stimulant and is indicated for the treatment of attention-deficit/hyperactivity disorder. A single-centre, double-blind, randomised, placebo-controlled, 6-period crossover study evaluated the abuse potential of single oral doses of 50, 100 (equivalent to 40 mg d-amphetamine), and 150 mg LDX, 40 mg d-amphetamine and 200 mg diethylpropion in 36 individuals with a history of stimulant abuse. On the primary abuse liability measure, maximum change of the Drug Rating Questionnaire-Subject Liking Scale compared with placebo, d-amphetamine and diethylpropion showed significant differences of 4.5 and 4.0 units, respectively (P < 0.001 for both vs placebo). LDX, administered at 50, 100 and 150 mg, showed nonsignificant differences of 2.0 and 2.1 units, respectively, at the two lower doses but a significant (P < 0.001 vs placebo) difference of 6.1 units at the highest dose. Subjects significantly favoured d-amphetamine 40 mg versus LDX 100 mg (2.4 units difference; P < 0.05). There was no significant difference in liking scores between d-amphetamine 40 mg and LDX 150 mg. Drug Rating Questionnaire-Subject Feel-Drug-Effect score was significantly lower for 100 mg LDX than for 40 mg d-amphetamine. There were no statistically significant differences between LDX and diethylpropion hydrochloride, a Schedule IV amphetamine-like stimulant, on abuse-related liking scores. Cardiovascular responses of LDX and d-amphetamine were similar at equivalent doses. In conclusion, at an equivalent amount of amphetamine base taken orally, LDX 100 mg had attenuated responses on measures of abuse liability compared with immediate-release d-amphetamine 40 mg. Abuse-related liking scores of LDX at a dose corresponding to a 50% higher amphetamine base (LDX 150 mg) were similar to d-amphetamine 40 mg.

The prognostic value of polymorphisms in the insulin-like growth factor receptor (IGFR) pathway in patients with locally advanced pancreatic cancer (LAPC)

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Background: The IGFR pathway is activated in pancreatic cancer and may result in aggressive disease course. The study of single nucleotide polymorphisms (SNPs) involved in this pathway may provide prognostic information and predict response to IGFR directed agents. We investigated IGFR pathway SNPs in patients with LAPC. Methods: We evaluated 39 SNPs from 7 candidate genes in the IGFR pathway (IGF1R, IGF2R, IGF1, IGF2, IRS1, IRS2, IGFBP3) in 105 LAPC patients. DNA extraction from whole blood was performed using the Qiagen Flexigene DNA and Promega Maxwell 16 kits. Genotyping was performed using the Sequenom method. Overall survival was measured from date of diagnosis to date of death or last follow-up. Kaplan-Meier plot, log-rank test, and Cox regression were used to compare survival of patients according to genotype corrected for previously identified prognostic factors, including induction chemotherapy, CA 19–9, albumin, LDH, hemoglobin and Karnofsky performance status (KPS). Results: Median survival time (MST) was 15 months (95% CI 13.3–16.7). Induction chemotherapy, LDH, CA 19–9 level, hemoglobin, and KPS were not significantly associated with survival. Serum albumin and three SNPs of the IGF pathway (IGF1R IVS20–3431A>G, IRS1 G971R, and IGF2 *4352A>G) were significantly associated with prognosis ( Table ). Two of the three genotypes remained as significant predictors for survival in Cox regression analysis when adjusted for clinical factors. A significant combined genotype effect was observed wherein patients with all three deleterious alleles had significantly worse survival than those with only two or one (10 vs. 16.3 vs. 21.3 months, p< 0.0001). Conclusions: These data suggest that SNPs in the IGFR pathway genes may have prognostic value for LAPC patients. This information may identify population subgroups that could benefit from IGFR-targeted agents.

[Table: see text]

No significant financial relationships to disclose.

Association of sTNF-R1 and the development of treatment-related symptoms in patients undergoing concurrent chemoradiation therapy for colorectal or esophageal cancer

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Background: Cancer-treatment-induced dysregulation of proinflammatory cytokines may be a common mechanism underlying the development of symptom burden (e.g., pain, fatigue, distress, and disturbed sleep) during concurrent chemoradiation therapy (CXRT). Methods: Patients undergoing CXRT for locally advanced colorectal or esophageal cancer (N=97) reported symptoms weekly via the M. D. Anderson Symptom Inventory (MDASI). Serum samples were tested weekly during therapy for changes in concentration levels of inflammatory cytokines (interleukin [IL]-6, IL-8, IL-10, IL-1 receptor antagonist [IL-1RA], vascular endothelial growth factor [VEGF], and soluble tumor necrosis factor receptor type 1 [sTNF-R1]) via enzyme-linked immunosorbent assay (ELISA). Symptom responses were modeled using longitudinal ordinal probit regression functions that included these serum cytokine values, along with age, cancer type, prechemotherapy status, and race (non-Hispanic white vs. others), as explanatory variables. Results: The severity of multiple symptoms significantly increased at week 4 and peaked around the end of CXRT (weeks 5–7). We found that an increase in the serum level of sTNF-R1 was significantly associated with an increase in the severity of 14 of the 16 MDASI symptoms individually over the course of CXRT, as well as with each of the 6 interference items (all p<.001). Even when week of observation was added as a variable to account for concurrent systematic trends in symptom reports and cytokine levels, sTNF-R1 retained a significant positive association with 14 of 16 symptoms, and IL-6 also showed a significant positive association with 6 of 16 symptoms. Conclusions: Longitudinal analysis identified temporal associations between increases in level of serum sTNF-R1 (and, to a lesser degree, IL-6) and the development of multiple symptoms in patients undergoing CXRT for colorectal and esophageal cancer. The results may be indicative of these cytokines as potential intervention targets of reducing aggressive chemoradiation-induced symptom burden.

No significant financial relationships to disclose.

Acute renal failure in intensive care unit

A retrospective study was done to analyse the incidence and outcome of acute renal failure among all patients admitted in intensive care unit (ICU) of Apollo Hospital, Secunderabad during the 12-month period from March 2003 to February 2004. Of the total 1100 patients admitted in ICU during the period, 75 patients were diagnosed with acute renal failure considering the primary markers as the levels of nitrogenous compounds in blood, i.e., blood urea nitrogen and serum creatinine. Sepsis in 24 (32%), hypoperfusion in 46 (61.3%), nephrotoxic drugs in 3, contrast induced in 1 and 20 patients with surgical ailments were the factors responsible for causing acute renal failure in various combinations. Thirty-three patients required dialytic support. Of the 75 patients, 29 died and of those who survived 9 had partial recovery. The overall mortality in ICU was 8.1% as compared to mortality among acute renal failure in ICU setting at 38.7%. Sepsis, oliguria and hypotension and scores over 120 on the Apache III scoring system were indicators of poor outcome. More than one pathogenetic factor playing a role in the development of acute renal failure in the majority. Acute renal failure can be prevented in several cases or the severity reduced by appropriate measures.

Synergy of gatifloxacin with cefoperazone and cefoperazone-sulbactam against resistant strains of Pseudomonas aeruginosa

Chequerboard and time-kill methods were used to compare the in vitro efficacies of the combinations gatifloxacin (GAT) with cefoperazone (CFP) and GAT with cefoperazone-sulbactam (CFP-SUL) against 58 clinical isolates of Pseudomonas aeruginosa. The combinations GAT+CFP and GAT+CFP-SUL were shown to be synergistic for 36.2 and 58.6 % of isolates tested, respectively, using the chequerboard method. Time-kill studies with 11 strains showed synergy in 54.5 % for the GAT+CFP combination and 72.7 % for the GAT+CFP-SUL combination. The agreement between these two methods was found to be 72-81 %. There was a significant difference in synergy between the two combinations tested (P=0.011).

Optimizing cardiac resuscitation outcomes using wavelet analysis

Ventricular fibrillation (VF) is the most lethal of cardiac arrhythmias that leads to sudden cardiac death if untreated within minutes of its occurrence. Defibrillation using electric shock resets the heart to return to spontaneous circulation (ROSC) state, however the success of which depends on various factors such as the viability of myocardium and the time lag between the onset of VF to defibrillation. Recent studies have reported that performing cardio pulmonary resuscitation (CPR) procedure prior to applying shock increases the survival rate especially when VF is untreated for more than 5 minutes. Considering the limited time within which the VF has to be treated for better survival rates, the choice of the right therapy (shock parameters, shock first or CPR first, drug administration) is vital. In aiding this choice, it would be of immense help for emergency medical staff (EMS) if an objective feedback could be provided at near real-time rate on the VF characteristics and its relation to the shock outcomes. Existing works in the literature have demonstrated correlation between the characteristics of the VF waveform and the outcome (ROSC) of the defibrillation. The proposed work improves on this by attempting to arrive at a near real-time monitoring tool in aiding the EMS staff. Using data collected from 16 pigs during VF, the proposed wavelet methodology achieved an overall accuracy of 94% in successfully predicting the shock outcomes.

A sensitive and high dynamic range cw laser power meter

We report the design of a cost effective, highly sensitive cw laser power meter with a large dynamic range based on a photodiode. The power meter consists of a photodiode, a current to voltage converter circuit, an offset balancing circuit, a microcontroller, an analog to digital converter, reed relays, and an alphanumeric liquid crystal display. The power meter can record absolute laser power levels as low as 1 pW. The dynamic range measured with a cw laser at a wavelength of 532 nm is 8x10(10). The high sensitivity and large dynamic range are achieved by the implementation of an analog background balancing circuit and autoranging.

Effects of donepezil on cortical activation in mild cognitive impairment: a pilot double-blind placebo-controlled trial using functional MR imaging

BACKGROUND AND PURPOSE

Cholinesterase-inhibitor therapy is approved for treatment of Alzheimer disease; however, application in patients with mild cognitive impairment (MCI) is still under active investigation. The purpose of this study was to determine the effect of such therapy on the neural substrates underlying memory processing in subjects with MCI by using functional MR imaging (fMRI).

MATERIALS AND METHODS

Thirteen subjects with MCI (mean age, 68 +/- 6.9 years) enrolled in a multicenter double-blind placebo-controlled trial testing the clinical efficacy of the cholinesterase-inhibitor, donepezil, were studied with fMRI at baseline and following 12 or 24 weeks of therapy (single-site pilot study). The cognitive paradigm was delayed-response visual memory for novel faces. Within-group 1-sample t tests were performed on the donepezil and placebo groups at baseline and at follow-up. A repeated-measures analysis of variance design was used to look for a Treatment Group x Time interaction showing a significant donepezil- but not placebo-related change in blood oxygen level-dependent response during the course of the study.

RESULTS

At baseline, both groups showed multiple areas of activation, including the bilateral dorsolateral prefrontal cortex, fusiform gyrus, and anterior cingulate cortex. On follow-up, the placebo group demonstrated a decreased extent of dorsolateral prefrontal activation, whereas the donepezil group demonstrated an increased extent of activation in the ventrolateral prefrontal cortex. Interaction demonstrated significant donepezil- but not placebo-related change in the left inferior frontal gyrus.

CONCLUSIONS

Despite the limitations inherent to a pilot study of a small sample, our results point to specific cortical substrates underlying the actions of donepezil, which can be tested in future studies.