Safety and Efficacy of Sildenafil Citrate for the Treatment of Female Sexual Arousal Disorder: A Double-Blind, Placebo Controlled Study

PURPOSE

We evaluated the efficacy and safety of sildenafil citrate in spontaneously or surgically postmenopausal women with female sexual arousal disorder (FSAD).

MATERIALS AND METHODS

Sildenafil (a 50 mg dose adjustable to 100 or 25 mg) was evaluated in a 12-week, double-blind, placebo controlled study in 202 postmenopausal women with FSAD who had protocol specified estradiol and free testosterone concentrations, and/or were receiving estrogen and/or androgen replacement therapy. Patients were excluded if emotional, relationship or historical abuse issues contributed significantly to sexual dysfunction. Primary end points were questions 2 (increased genital sensation during intercourse or stimulation) and 4 (increased satisfaction with intercourse and/or foreplay) from the Female Intervention Efficacy Index (FIEI). Secondary end points were the remaining questions from this index, the Sexual Function Questionnaire and sexual activity event log questions.

RESULTS

Significant improvements in FIEI questions 2 (p = 0.017) and 4 (p = 0.015) were noted with sildenafil compared with placebo. For women with FSAD without concomitant hypoactive sexual desire disorder (HSDD) sildenafil was associated with significantly greater improvement in 5 of 6 FIEI items compared with placebo (p <0.02). No significant improvements were shown for women with concomitant HSDD. Most adverse events were mild to moderate with headache, flushing, rhinitis, nausea and visual symptoms reported most frequently.

CONCLUSIONS

Sildenafil was effective and well tolerated in postmenopausal women with FSAD without concomitant HSDD or contributory emotional, relationship or historical abuse issues. All patients had protocol specified estradiol and free testosterone concentrations or were receiving estrogen and/or androgen replacement therapy.

Phase 2 Trial of an Alpha-7 Nicotinic Receptor Agonist (TC-5619) in Negative and Cognitive Symptoms of Schizophrenia

OBJECTIVES

This trial was conducted to test the effects of an alpha7 nicotinic receptor full agonist, TC-5619, on negative and cognitive symptoms in subjects with schizophrenia.

METHODS

In 64 sites in the United States, Russia, Ukraine, Hungary, Romania, and Serbia, 477 outpatients (18-65 years; male 62%; 55% tobacco users) with schizophrenia, treated with a new-generation antipsychotic, were randomized to 24 weeks of placebo (n = 235), TC-5619, 5mg (n = 121), or TC-5619, 50 mg (n = 121), administered orally once daily. The primary efficacy measure was the Scale for the Assessment of Negative Symptoms (SANS) composite score. Key secondary measures were the Cogstate Schizophrenia Battery (CSB) composite score and the University of California San Diego Performance-Based Skills Assessment-Brief Version (UPSA-B) total score. Secondary measures included: Positive and Negative Syndrome Scale in Schizophrenia (PANSS) total and subscale scores, SANS domain scores, CSB item scores, Clinical Global Impression-Global Improvement (CGI-I) score, CGI-Severity (CGI-S) score, and Subject Global Impression-Cognition (SGI-Cog) total score.

RESULTS

SANS score showed no statistical benefit for TC-5619 vs placebo at week 24 (5 mg, 2-tailed P = .159; 50 mg, P = .689). Likewise, no scores of CSB, UPSA-B, PANSS, CGI-I, CGI-S, or SGI-Cog favored TC-5619 (P > .05). Sporadic statistical benefit favoring TC-5619 in some of these outcome measures were observed in tobacco users, but these benefits did not show concordance by dose, country, gender, or other relevant measures. TC-5619 was generally well tolerated.

CONCLUSION

These results do not support a benefit of TC-5619 for negative or cognitive symptoms in schizophrenia.

Two-Dimensional Regulation of CAR-T Cell Therapy with Orthogonal Switches

Use of chimeric antigen receptors (CARs) as the basis of targeted adoptive T cell therapies has enabled dramatic efficacy against multiple hematopoietic malignancies, but potency against bulky and solid tumors has lagged, potentially due to insufficient CAR-T cell expansion and persistence. To improve CAR-T cell efficacy, we utilized a potent activation switch based on rimiducid-inducible MyD88 and CD40 (iMC)-signaling elements. To offset potential toxicity risks by this enhanced CAR, an orthogonally regulated, rapamycin-induced, caspase-9-based safety switch (iRC9) was developed to allow in vivo elimination of CAR-T cells. iMC costimulation induced by systemic rimiducid administration enhanced CAR-T cell proliferation, cytokine secretion, and antitumor efficacy in both in vitro assays and xenograft tumor models. Conversely, rapamycin-mediated iRC9 dimerization rapidly induced apoptosis in a dose-dependent fashion as an approach to mitigate therapy-related toxicity. This novel, regulatable dual-switch system may promote greater CAR-T cell expansion and prolonged persistence in a drug-dependent manner while providing a safety switch to mitigate toxicity concerns.

An information seeking disposition in child surgery patients

Several studies in the last decade have demonstrated the importance of considering an information seeking versus information avoiding coping dimension in adult medical patients. However, there have been few empirical demonstrations of such a dimension in children. The present study utilized the Coping Strategies Interview to assign an information seeking score to child elective surgery patients. This information seeking score was related to several parent-rated variables, including the child's historical success in coping with medical procedures, the child's typical preference for information acquisition, and the child's typically emitted coping behaviors. In addition, the information seeking score was related to question asking and discussion of medical procedures as rated by an objective observer during the blood test, by the nurse during anesthesia induction, and by the parent during recovery from surgery. It was strongly related to the information acquired prior to hospitalization. Information seeking was also related to stress responses, such that high information seeking scores predicted more adaptive behaviors prior to the blood test. This cross-rater and cross-situation validation suggests the existence of an information seeking dimension in children and the utility of considering this dimension in future research.

Oxidative Stress Plays an Important Role in the Pathogenesis of Drug-Induced Retinopathy

Several pharmaceutical agents have been associated with rare but serious retinopathies, some resulting in blindness. Little is known of the mechanism(s) that produce these injuries. Mechanisms proposed thus far have not been embraced by the medical and scientific communities. However, preclinical and clinical data indicate that oxidative stress may contribute substantially to iatrogenic retinal disease. Retinal oxidative stress may be precipitated by the interaction of putative retinal toxins with the ocular redox system. The retina, replete with cytochromes P450 and myeloperoxidase, may serve to activate xenobiotics to oxidants, resulting in ocular injury. These activated agents may directly form retinal adducts or may diminish ocular reduced glutathione concentrations. Data are reviewed that suggest that indomethacin, tamoxifen, thioridazine, and chloroquine all produce retinopathies via a common mechanism—they produce ocular oxidative stress.

Pyrazolinone-piperidine dipeptide growth hormone secretagogues (GHSs). Discovery of capromorelin

Novel pyrazolinone-piperidine dipeptide derivatives were synthesized and evaluated as growth hormone secretagogues (GHSs). Two analogues, capromorelin (5, CP-424391-18, hGHS-R1a K(i)=7 nM, rat pituicyte EC(50)=3 nM) and the des-methyl analogue 5c (hGHS-R1a K(i)=17 nM, rat pituicyte EC(50)=3 nM), increased plasma GH levels in an anesthesized rat model, with ED(50) values less than 0.05 mg/kg iv. Capromorelin showed enhanced intestinal absorption in rodent models and exhibited superior pharmacokinetic properties, including high bioavailabilities in two animal species [F(rat)=65%, F(dog)=44%]. This short-duration GHS was orally active in canine models and was selected as a development candidate for the treatment of musculoskeletal frailty in elderly adults.

Selective enhancement of cellular oxidative stress by chloroquine: implications for the treatment of glioblastoma multiforme

Chloroquine is used in the treatment of malaria, a disease caused by infection with the parasite Plasmodium. Although chloroquine appears to possess diverse pharmacological activity, its plasmodicidal activity results from augmentation of parasite oxidative stress. Chloroquine also appears to augment oxidative stress in metabolically active mammalian cells, including human astroglial cells. The authors propose that chloroquine may augment oxidative stress induced by radiotherapy in the treatment of glioblastoma multiforme, enhancing therapeutic efficacy. Such an effect would be consistent with the known pharmacological effects of chloroquine observed in Plasmodium. Other selective redox agents, such as tempol and artemisinin, should be investigated clinically for therapeutic benefit when coadministered with combined radio- and chemotherapy for cancer.

Multiple-dose pharmacokinetics of concurrent oral ciprofloxacin and rifampin therapy in elderly patients

The purpose of this clinical study was to investigate the influence of concomitant drug therapy with ciprofloxacin and rifampin on the individual pharmacokinetic profile of each agent in elderly patients. Twelve nursing home patients (age, 74 +/- 7 years), colonized with methicillin-resistant Staphylococcus aureus, were randomized to receive 14-day therapy with oral ciprofloxacin (750 mg every 12 h) (group A; n = 6) or ciprofloxacin (750 mg every 12 h) and oral rifampin (300 mg every 12 h) (group B; n = 6). Serial blood samples were obtained from 0 to 12 h following ciprofloxacin doses 1 and 13 and from 0 to 36 h after the last ciprofloxacin dose. No significant differences (P greater than 0.05) were found between or within groups in any pharmacokinetic parameter. The mean ciprofloxacin oral clearance values were 0.35 +/- 0.06, 0.41 +/- 0.15, and 0.38 +/- 0.11 liter/h per kg for doses 1, 13, and 28, respectively, in group A patients. The mean oral clearance values in group B patients for the respective doses were 0.53 +/- 0.36, 0.32 +/- 0.13, and 0.36 +/- 0.17 liter/h per kg. Likewise, no significant differences (P greater than 0.05) in rifampin pharmacokinetic parameters were found when compared with historical controls. These data suggest that ciprofloxacin and rifampin may be given concomitantly in standard clinical dosing regimens. The combination results in therapeutic levels of both drugs and appears to be safe for administration to elderly nursing home patients.

Preclinical pharmacology of CP-424,391, an orally active pyrazolinone-piperidine [correction of pyrazolidinone-piperidine] growth hormone secretagogue

Growth hormone secretagogues (GHSs) represent attractive therapeutic alternatives to recombinant growth hormone (GH), given their ability to amplify pulsatile hormone secretion in a relatively physiologic manner. CP-424,391 (391) is a novel, orally active pyrazolinone-piperidine [corrected] GHS. In rat pituitary cell cultures, 391 stimulated GH release with an EC50 = 3 nM. The addition of 391 to rat pituitary cells activated intracellular calcium signaling but did not elevate intracellular cyclic adenosine monophosphate (cAMP). 391 also modulated the effects of GH-releasing hormone and somatostatin on pituitary cell GH-release and intracellular signaling. In nonpituitary cell lines, the ability of 391 to stimulate intracellular signaling was dependent on the expression of recombinant human GHS receptor. Acute administration of 391 to anesthetized rats or to conscious dogs induced pulsatile release of G H in a dose-dependent manner. Plasma insulin-like growth factor-I (IGF-I) was elevated progressively over a 5-d course of daily oral dosing in dogs. Chronic oral administration of 391 augmented body weight gain in rats and dogs. Thus, the peptidomimetic GHS 391 has potential utility for the treatment of clinical conditions that could benefit from systemic augmentation of GH and IGF-I levels.

Discovery and biological characterization of capromorelin analogues with extended half-lives

New tert-butyl, picolyl and fluorinated analogues of capromorelin (3), a short-acting growth hormone secretagogue (GHS), were prepared as part of a program to identify long-acting GHSs that increase 24-h plasma IGF-1 levels. Compounds 4c and 4d (ACD LogD values >or=2.9) displayed extended plasma elimination half-lives in dogs, primarily due to high volumes of distribution, but showed weak GH secretagogue activities in rats (ED(50)s>10 mg/kg). A less lipophilic derivative 4 (ACD LogD=1.6) exhibited a shorter canine half-life, but stimulated GH secretion in two animal species. Repeat oral dosing of 4 in dogs for 29 days (6 mg/kg) resulted in a significant down-regulation of the post dose GH response and a 60 and 40% increase in IGF-1 levels relative to pre-dose levels at the 8- and 24-h post dose time points. Compound 4 (CP-464709-18) has been selected as a development candidate for the treatment of frailty.

A double-blind placebo-controlled evaluation of the acute effects of sildenafil citrate (Viagra) on visual function in subjects with early-stage age-related macular degeneration

PURPOSE

To assess the effects of a single 100-mg dose of sildenafil citrate on visual function in men with early-stage age-related macular degeneration.

DESIGN

Randomized double-blind placebo-controlled clinical trial.

METHODS

Nine men (mean age 71 years, range 59-85 years) with early-stage (minimal visual impairment and large drusen in the macula) age-related macular degeneration and 20/40 or better-corrected visual acuity in at least one eye were prospectively randomized to receive either placebo or sildenafil citrate (Viagra; Pfizer Inc, New York, New York) 100 mg as a single oral dose. After 7-14 days, they received the alternate treatment. Subjects underwent visual acuity, Amsler grid, color discrimination (D15), traffic light, Humphrey perimetry, and photo-stress testing in each eye before and at specific intervals within 8 hours after dosing.

RESULTS

Compared with placebo, no pattern of errors were evident in any visual function test following sildenafil administration. No statistically or clinically relevant changes from baseline were observed in visual acuity, Humphrey perimetry (corrected pattern standard deviation), D15 color discrimination, or photo-stress tests. No clinically relevant changes were observed in the Amsler grid or traffic light tests. Sildenafil treatment was associated with transient mild or moderate headache, flushing, and rhinitis. There were no visual adverse events spontaneously reported to the investigator.

CONCLUSION

A single 100-mg dose of sildenafil was well tolerated and produced no acute visual effects or exacerbation of preexisting visual impairment in nine men with early-stage age-related macular degeneration.

Severe phenytoin intoxication as a result of altered protein binding in AIDS

Alterations in plasma protein binding may alter patient response to pharmaceutical agents because only free drug is considered to be pharmacologically active. Such alterations appear to be more significant with highly bound agents such as phenytoin. Traditionally, most drug assays monitor total drug concentrations and do not quantitate free drug. When binding alterations are present, total drug concentrations may mislead clinicians in evaluating patient response. We describe a case in which profound hypoalbuminemia (0.2 g/dL), associated with focal segmental glomerulosclerosis, produced toxic free phenytoin concentrations (4.9 micrograms/mL) in an HIV-positive 25-year-old black woman. At such a high serum concentration of free phenytoin, the patient exhibited seizure-like effects. Renal abnormalities and hypoalbuminemia associated with acquired immunodeficiency syndrome (AIDS) may place patients at risk for elevated free fractions of phenytoin and subsequent toxicity.

Creatine is an ergogen for anaerobic exercise

Throughout history, athletes have searched for performance-enhancing agents. Recently, creatine (N-[aminoiminomethyl]-N-methyl glycine) has been marketed as an ergogenic dietary supplement. There appears to be scientific merit to the claim that creatine is ergogenic when taken in large amounts. However, several issues regarding its use need to be addressed.

Intraperitoneal and intraportal administration of droloxifene to the Sprague-Dawley rat: assessing the first-pass effect

1. Employing droloxifene as a probe substrate, we have compared the use of intraperitoneal injection and intraportal infusion, where the rate and duration of intraportal drug administration were designed to approximate those observed after oral drug delivery, as methods of discriminating between high first-pass hepatic extraction and poor oral absorption. 2. Intraperitoneal injection of droloxifene (1 mg/kg) yielded an AUC0-omega approximately twice that observed following intraportal infusion or oral delivery of equal doses. 3. Our findings suggest that hepatic first-pass metabolism may have been saturated following intraperitoneal drug administration due to the rapid rate of absorption and the corresponding high drug concentrations achieved. 4. Application of a model in which intraportal drug infusion rates are designed to mimic the oral absorption rate appears warranted under such circumstances.

Sensitive method for the quantitation of droloxifene in plasma and serum by high-performance liquid chromatography employing fluorimetric detection

A simple and highly sensitive reversed-phase fluorimetric HPLC method for the quantitation of droloxifene from rat, monkey, and human plasma as well as human serum is described. This assay employs solid-phase extraction and has a dynamic range of 25 to 10,000 pg/ml. Sample extraction (efficiencies > 86%) was accomplished using a benzenesulfonic acid (SCX) column with water and methanol rinses. Droloxifene and internal standard were eluted with 1 ml of 3.5% (v/v) ammonium hydroxide (30%) in methanol. Samples were quantitated using post-column UV-photochemical cyclization coupled with fluorimetric detection with excitation and emission wavelengths of 260 nm and 375 nm, respectively. Relative ease of sample extraction and short run times allow for the analysis of approximately 100 samples per day.

First-pass metabolism and biliary recirculation of droloxifene in the female Sprague-Dawley rat

1. Utilizing a validated ultrasensitive hplc assay (lower limit of quantitation 25 pg/ml), we characterized the disposition profile of droloxifene in the female Sprague-Dawley rat following intravenous, oral and intraportal administration. 2. The site and extent of first-pass metabolism and the extent of enterohepatic recirculation were investigated. 3. Our findings suggest that the intestine is neither a metabolic nor an absorptive barrier to the bioavailability of droloxifene in the female Sprague-Dawley rat and that first-pass hepatic extraction is approximately 70-80% following an oral dose of 1 mg/kg. 4. Employment of a modified linked-rat model revealed that droloxifene is subject to enterohepatic recirculation (approximately 5%) in the rat.

Invited Review: Fluphenazine Augments Retinal Oxidative Stress

Recently, fluphenazine, a phenothiazine neuroleptic, has been associated with idiosyncratic retinopathy. Neuroleptic-induced retinopathy appears to be isolated to only a few structurally related phenothiazines, suggesting that the causality is not the result of dopamine antagonism. The chemical structure of fluphenazine is very similar to that of chlorpromazine and thioridazine, agents known to produce retinopathy. Like chlorpromazine and thioridazine, fluphenazine may be oxidized by retinal cytochrome P450 and/or myeloperoxidase to an electrophile, producing injury in susceptible patients.

An information seeking disposition in child surgery patients

Several studies in the last decade have demonstrated the importance of considering an information seeking versus information avoiding coping dimension in adult medical patients. However, there have been few empirical demonstrations of such a dimension in children. The present study utilized the Coping Strategies Interview to assign an information seeking score to child elective surgery patients. This information seeking score was related to several parent-rated variables, including the child's historical success in coping with medical procedures, the child's typical preference for information acquisition, and the child's typically emitted coping behaviors. In addition, the information seeking score was related to question asking and discussion of medical procedures as rated by an objective observer during the blood test, by the nurse during anesthesia induction, and by the parent during recovery from surgery. It was strongly related to the information acquired prior to hospitalization. Information seeking was also related to stress responses, such that high information seeking scores predicted more adaptive behaviors prior to the blood test. This cross-rater and cross-situation validation suggests the existence of an information seeking dimension in children and the utility of considering this dimension in future research.

Evaluation of precision and accuracy of a fluorescence polarization immunoassay system after dilution of serum samples containing fluorescein dye

The accuracy and precision of a fluorescence polarization immunoassay for diluted gentamicin serum samples in the presence of fluorescein dye is described.

Head injury and cytochrome P-450 enzymes. Differential effect on mRNA and protein expression in the Fischer-344 rat

Head trauma produces debilitating injuries that affect millions of people each year. Such injuries lead to a cascade of physiologic sequelae resulting in a hypercatabolic/hypermetabolic state. Current information describing changes in hepatic drug metabolism as a result of head trauma is limited. In this study, the effect of craniotomy and craniotomy plus cerebral percussive injury (impact) were investigated and compared with anesthesia control. Steady-state mRNA levels for CYP2C11 and CYP3A were suppressed to 50% of control values 24 hr following injury for the impact treatments. Craniotomy treatments also demonstrated a 50% decline in steady-state levels of mRNA for CYP3A 24 hr following injury. However, Western blot analysis of the CYP3A enzyme revealed no change at 6, 24, or 48 hr following injury. In addition, activities for 2 alpha- and 6 beta-testosterone hydroxylase did not differ from control values at any time point. Spectral analysis of total P-450 demonstrated a very small decline of 15% for the impact treatment 48 hr following injury. Total cytochrome P-450 content did not differ from control values at any other time point. Head injury produces a profound decline in steady-state mRNA concentrations for CYP2C11 and CYP3A that do not translate into altered protein expression.