Enhancing the utility of alanine aminotransferase as a reference standard biomarker for drug-induced liver injury.

Drug-induced liver injury (DILI) is the most frequent cause of discontinuation of new chemical entities during development. DILI can either be intrinsic/predictable or an idiosyncratic type. These two forms of DILI are contrasted in their manifestation and diagnosis. Even with regulatory guidance (FDA, 2009), there is still a gap in our ability to identify predictable DILI, both specifically and sensitively. Alanine aminotransferase (ALT) is the principal reference standard biomarker to diagnose DILI, yet its current application in preclinical to clinical translation for decision-making purposes has imperfections: (1) analytical ALT assay uniformity across industry would be aided by common analytical processes; (2) assessment of ALT toxicological performance in a large preclinical analysis would help to establish a true threshold of elevation for predictable DILI and improve translational use across various stages of pharmaceutical development and finally, (3) clinical evaluation of ALT elevations prospectively and retrospectively is recommended to define and manage variations in clinical study subjects including rising body mass index (BMI) range and ALT upper limit of normal (ULN) in the broader population over time. The emergence of new hepatotoxicity biomarkers necessitates a parallel and equivalent assessment to the aminotransferases in a regulatory qualification model.

Efficacy and safety of recombinant growth hormone treatment in children with growth retardation related to long-term glucocorticosteroid therapy.

OBJECTIVE: To evaluate safety and efficacy of recombinant human growth hormone treatment in children on long-term glucocorticoid therapy. METHODS: A 5-year prospective open-label study included children on glucocorticoid therapy with either standard deviation score (SDS)<-2 for height for chronological age (CA) if naïve to growth hormone treatment, or annual growth rate≥0 SDS for CA if currently receiving growth hormone. RESULTS: Ninety-eight patients began treatment, 63 discontinued; 59 were analyzed for safety and 58 for efficacy. There was male predominance (78.0%). Median age was 13.0 years. Median height screening was 136.0cm (range, 95.1-159.7cm). Mean SDS for height for CA in the efficacy analysis set was -2.91±1.19 (range, -7.49 to -0.96). Mean growth hormone dose was 0.4, 0.4, 0.4 and 0.3mg/kg/week at month 0, M12, M24, and M36, respectively. Primary analysis of change in SDS for height for CA from baseline to M36 showed a significant increase of 0.80±1.03. Twenty patients in the safety analysis set had≥1 treatment-emergent adverse event (TEAE) related to study treatment. Two patients experienced serious treatment-related TEAEs: 1 case of poor compliance, and 1 of mild hyperglycemia, both already observed under growth hormone treatment. CONCLUSION: This study suggests that growth hormone treatment could be effective in increasing height in children on long-term glucocorticoid treatment with a safety profile comparable to that in approved rhGH treatment indications. CLINICAL TRIAL REGISTRATION: NCT00163189.

Use of cGMP PDE5 inhibitors in the treatment of neuropathy: a review of the patent literature.

In addition to the classic roles that cyclic-3',5-guanosine monophosphate (cGMP) is thought to play in cell function regulation, such as smooth muscle regulation, inhibition of platelet aggregation, visual signal conduction and neutrophil degranulation, it is now understood to be involved with various physiological functions. The tissue levels and hence activity of cGMP are determined by the balance between production rates from guanosine triphosphate (GTP) through the guanylyl cyclase pathways, and degradation to GMP by specific cyclic nucleotide phosphodiesterases (PDEs). PDE5 inhibitors were initially developed for a possible role in cardiovascular disease; their role in the treatment of erectile dysfunction was brought to the forefront by the development of sildenafil. The focus of this article is the current patent literature around the use of PDE5 inhibitors for neuropathy. It also explores the possible hypotheses that may help to explain the mechanism(s) by which cGMP PDE5 inhibitors could have potential benefits in neuropathy.

Recent advances in the treatment of erectile dysfunction in patients with diabetes mellitus.

OBJECTIVE: To present current information on the pathogenesis of and available therapeutic options for erectile dysfunction (ED) in patients with diabetes. METHODS: We provide a detailed review of the following topics: (1) peripheral and central neurotransmitter pathways involved in the penile erectile process (for example, nitric oxide, acetylcholine, vasoactive intestinal polypeptide, and prostaglandin E(1)), (2) pathogenesis of ED in patients with diabetes (vascular insufficiency, endothelial dysfunction, and autonomic neuropathy), (3) currently available treatment options for ED and their advantages and disadvantages, (4) potential new avenues for future research, and (5) the possibility of preventive treatment. RESULTS: Clearly a need exists for effective treatment options for ED in patients with diabetes. Because the development of ED in patients with diabetes is often caused by several interrelated mechanisms, including vascular disease, endothelial dysfunction, autonomic neuropathy, hormone imbalance, and certain medications, a thorough understanding of the various pathways involved in penile erection and their modulation in diabetes is essential for physicians to design an effective treatment plan. Interventions that modulate the erectile pathway at different points include therapies that enhance the erectile mechanism (amplification of the nitric oxide pathway), inhibit the detumescence mechanism, or affect the final common pathway by augmenting smooth muscle relaxation. Oral therapy, intracavernosal injections, transurethral pellets, combination therapy, and surgical procedures are available treatment strategies. CONCLUSION: Despite the availability of many treatment options for ED, early intervention and prevention (by such measures as improved glycemic control and general reduction of associated risk factors) should be emphasized because many of the diabetes-related complications leading to ED are irreversible.

Evaluation of the nonsteroidal anti-inflammatory drug-sparing effect of etanercept in axial spondyloarthritis: results of the multicenter, randomized, double-blind, placebo-controlled SPARSE study.

INTRODUCTION: In clinical practice, nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly discontinued after response to biologic therapy is achieved in patients with axial spondyloarthritis (axSpA), but the impact of NSAID discontinuation has not been assessed in prospective controlled trials. The aim of the SPARSE study was to evaluate the effects of the anti-tumor necrosis factor agent etanercept on NSAID intake and conventional clinical outcomes in axSpA patients. METHODS: In the double-blind, placebo-controlled period, patients with active (mini Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) ≥4) axSpA despite optimal NSAID intake were randomized to receive etanercept 50 mg or placebo once weekly for 8 weeks. All patients were advised to taper/discontinue their NSAID intake during the treatment period. NSAID intake was self-reported by diary and Assessment of SpondyloArthritis International Society (ASAS)-NSAID scores calculated based on ASAS recommendations. The primary endpoint was change from baseline to week 8 in ASAS-NSAID score (analysis of covariance). RESULTS: In 90 randomized patients at baseline, mean age (standard deviation) was 38.9 (11.8) years; disease duration, 5.7 (8.1) years; 59/90 (66%) were human leukocyte antigen-B27 positive; 51/90 (57%) had radiographic sacroiliitis; and 45/90 (50%) were magnetic resonance imaging sacroiliitis-positive. Mean ASAS-NSAID scores were similar between etanercept and placebo groups at baseline (98.2 (39.0) versus 93.0 (23.4)), as were BASDAI (6.0 (1.7) versus 5.9 (1.5)), and Bath Ankylosing Spondylitis Functional Index (5.2 (2.1) versus 5.1 (2.2)). Mean changes (SE) in ASAS-NSAID score from baseline to week 8 were -63.9 (6.1) and -36.6 (5.9) in the etanercept and placebo groups (between-group difference, -27.3; P = 0.002). Significantly higher proportions of patients receiving etanercept versus placebo had an ASAS-NSAID score <10 (46% versus 17%; P = 0.008) and ASAS-NSAID score of 0 (41% versus 14%; P = 0.013) at this time point. Significantly more patients in the etanercept versus placebo group achieved BASDAI50 (39% versus 18%; P = 0.032) and ASAS40 (44% versus 21%; P = 0.028) at week 8. CONCLUSIONS: In patients with axSpA, etanercept was associated with clinically relevant NSAID-sparing effects in addition to significant improvements in conventional clinical outcomes. TRIAL REGISTRATION: ClinicalTrials.gov NCT01298531. Registered 16 February 2011.

Recommendations to qualify biomarker candidates of drug-induced liver injury.

Certain compounds that induce liver injury clinically are not readily identified from earlier preclinical studies. Novel biomarkers are being sought to be applied across the pharmaceutical pipeline to fill this knowledge gap and to add increased specificity for detecting drug-induced liver injury in combination with aminotransferases (alanine and aspartate aminotransferase)--the current reference-standard biomarkers used in the clinic. The gaps in the qualification process for novel biomarkers of regulatory decision-making are assessed and compared with aminotransferase activities to guide the determination of safe compound margins for drug delivery to humans where monitoring for potential liver injury is a cause for concern. Histopathologic observations from preclinical studies are considered the principal reference standard to benchmark and assess subtle aminotransferase elevations. This approach correlates quite well for many developmental compounds, yet cases of discordance create dilemmas regarding which standard(s) indicates true injury. Concordance amongst a broader set of biomarker injury signals in a qualification paradigm will increase confidence, leading to accepted and integrated translational biomarker signals during safety assessment processes across the pharmaceutical industry, with academia, in government and in contractor laboratories.

Efficacy of sildenafil citrate (Viagra) in men with premature ejaculation.

OBJECTIVES: Premature ejaculation (PE) is the most common ejaculatory dysfunction. We assessed the efficacy of sildenafil to increase the time to ejaculation, improve ejaculatory control, and decrease the postejaculatory erectile refractory time in men with PE. DESIGN AND METHODS: The main study was an 8-week, double-blind, placebo-controlled, parallel group study in men between 18 and 65 years of age with diagnosed PE. A substudy was also conducted using a subset of patients (two-way crossover, one center) before entry to the main study. The primary study measured intravaginal ejaculatory latency (IELT) and responses to the Index of Premature Ejaculation (IPE) questionnaire. The substudy measured vibrotactile stimulation ejaculatory latency time (VTS-ELT) and postejaculatory erectile refractory time. Differences between treatment groups were determined by ancova at the 5% level of significance. RESULTS: The change in IELT (1.6 +/- 6.08 vs. 0.6 +/- 2.07 minutes) and VTS-ELT (2.9 +/- 0.4 vs. 2.4 +/- 0.4 minutes) were higher after taking sildenafil, compared with placebo, but did not reach statistical significance. However, patients who took sildenafil (vs. placebo) reported significantly (P < 0.05) increased ejaculatory control (1.8 +/- 0.3 vs. 1.5 +/- 0.3), increased ejaculatory confidence (2.2 +/- 0.2 vs. 1.9 +/- 0.2), and improved overall sexual satisfaction scores (3.1 +/- 0.2 vs. 2.8 +/- 02) on the IPE, and had a decreased postejaculatory erectile refractory time (3.2 +/- 0.7 vs. 6.4 +/- 0.7 minutes). The most common adverse events for sildenafil (vs. placebo) were headache (15% vs. 1%), flushing (15% vs. 0%), dyspepsia (5% vs. 1%), abnormal vision (5% vs. 0%), and rhinitis (5% vs. 0%). CONCLUSIONS: Although IELT and VTS-ELT were not significantly improved, sildenafil increased confidence, the perception of ejaculatory control, and overall sexual satisfaction, and decreased the refractory time to achieve a second erection after ejaculation in men with PE.

Efficacy and safety of sildenafil citrate in women with sexual dysfunction associated with female sexual arousal disorder.

OBJECTIVE: Sildenafil citrate (Viagra Pfizer, New York, NY) is indicated for the treatment of erectile dysfunction in men. The nitric oxide-cyclic guanosine monophosphate pathway (NO-cGMP) involved in penile erection and enhanced by sildenafil may also play a role in some components of the female sexual arousal response. The efficacy and safety of sildenafil were evaluated in estrogenized and estrogen-deficient women with sexual dysfunction that included female sexual arousal disorder (FSAD). METHODS: Patients were randomized to receive 10-100 mg sildenafil or matching placebo. To assess efficacy, patients completed two global efficacy questions (GEQ), the Life Satisfaction Checklist (LSC), an event log of sexual activity, and a 31-item sexual function questionnaire (SFQ). To assess safety, adverse event (AE) data were recorded. RESULTS: A total of 577 estrogenized and 204 estrogen-deficient women were randomized to treatment. All were diagnosed with FSAD, but it was the primary presenting symptom in only 46% and 50% of women, respectively. Differences in efficacy between sildenafil and placebo were not significant for any patient or partner end points (e.g., the two GEQ, the sexual event logs, the LSC, and the SFQ). The main AE were headache, flushing, rhinitis, nausea, visual disturbances, and dyspepsia, which were generally mild to moderate in nature. CONCLUSIONS: Any genital physiological effect of sildenafil was not perceived as improving the sexual response in estrogenized or estrogen-deficient women with a broad spectrum of sexual dysfunction that included FSAD. Whether more specific subgroups of women with FSAD could potentially benefit from treatment with sildenafil is an area for future research.