Fetal echocardiography: z-score reference ranges for a large patient population

OBJECTIVES

The main goal was to develop new z-score reference ranges for common fetal echocardiographic measurements from a large referral population.

METHODS

A retrospective cross-sectional study of 2735 fetuses was performed for standard biometry (biparietal diameter (BPD) and femoral diaphysis length (FDL)) and an assessment of menstrual age (MA). Standardized fetal echocardiographic measurements included aortic valve annulus and pulmonary valve annulus diameters at end-systole, right and left ventricular diameters at end-diastole, and cardiac circumference from a four-chamber view of the heart during end-diastole. Normal z-score ranges were developed for these echocardiographic measurements using MA, BPD and FDL as independent variables. This was accomplished by using first standard regression analysis and then weighted regression of absolute residual values for each parameter in order to adjust for inconstant variance.

RESULTS

A simple, linear regression model was the best description of the data in each case and correlations between fetal cardiac measurements and the independent variables were excellent. There was significant heteroscedasticity of standard deviation with increasing gestational age, which also could be modeled with simple linear regression. After this adjustment, the residuals conformed to a normal distribution, validating the calculation and interpretation of z-scores.

CONCLUSION

Development of reliable z-scores is possible for common fetal echocardiographic parameters by applying statistical methods that are based on a large sample size and weighted regression of absolute residuals in order to minimize the effect of heteroscedasticity. These normative ranges should be especially useful for the detection and monitoring of suspected fetal cardiac size and growth abnormalities.

Inhibition of acetyl- and butyryl-cholinesterase in the cerebrospinal fluid of patients with Alzheimer's disease by rivastigmine: correlation with cognitive benefit

Cholinesterase (ChE) inhibition represents the most efficacious treatment approach for Alzheimer's disease (AD) to date. This multiple-dose study has examined the relationship between inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities in the cerebrospinal fluid (CSF) and cognitive change (measured by the Computerised Neuropsychological Test Battery [CNTB]) following administration of the ChE inhibitor, rivastigmine (Exelon). In 18 patients with mild to moderate AD, CNTB scores, activities of AChE and BuChE in the CSF, and plasma BuChE activity were determined prior to treatment with rivastigmine. Doses of rivastigmine were then titrated (1 mg b.i.d./week) to final doses of 1, 2, 3, 4, 5 or 6 mg b.i.d. (n = 3 per dose). Following treatment with the target dose of rivastigmine for at least 3 days, CNTB scores were re-determined. CSF samples were continuously collected together with plasma samples prior to and for 12 hours after the final dose of rivastigmine, and AChE and BuChE activities determined.AChE in CSF and BuChE in plasma were dose-dependently inhibited by rivastigmine treatment. The inhibition of BuChE in CSF was not clearly dose-dependent. A statistically significant correlation was observed between the change in CNTB summary score and inhibition of AChE activity (r = -0.56, p < 0.05) and BuChE activity (r = -0.65, p < 0.01) in CSF. Improvement in speed-, attention- and memory-related subtests of the CNTB correlated significantly with inhibition of BuChE but not AChE activity in CSF. Weak or absent correlation with change in cognitive performance was noted for inhibition of plasma BuChE. These results indicate that cognitive improvement with rivastigmine in AD is associated with central inhibition of ChEs and support a role for central BuChE in addition to AChE inhibition in modulating cholinergic function in AD.

Efficacy and safety of sibutramine for weight loss in obese patients with hypertension well controlled by beta-adrenergic blocking agents: a placebo-controlled, double-blind, randomised trial

Sibutramine is a serotonin-noradrenaline reuptake inhibitor that is effective for long-term weight reduction and maintenance in obese patients when used as an adjunct to dietary and behavioural measures. Because the inhibition of noradrenaline reuptake may be expected to increase systolic and diastolic blood pressure (SBP and DBP) and pulse rate (PR), a 12-week multi-centre, placebo-controlled, double-blind study was designed to evaluate the efficacy and tolerability of sibutramine for weight loss in obese patients whose hypertension was well controlled (DBP < or = 95 mm Hg) by beta-adrenergic blocking agents (beta-blockers), with or without concomitant thiazide diuretics. Of the 61 patients randomised to sibutramine 20 mg once daily or placebo, 55 patients (90%) completed the study. After 12 weeks, sibutramine-treated patients lost significantly more weight than placebo-treated patients: mean weight reductions were 4.2 kg (4.5%) in the sibutramine group vs 0.3 kg (0.4%) in the placebo group (P<0.001). Greater weight reduction on sibutramine was accompanied by trends for greater mean reductions in serum triglycerides and very low density lipoprotein cholesterol. Sibutramine was well tolerated, and most adverse events were mild or moderate in severity. No sibutramine patient discontinued treatment because of an adverse event. Mean supine and standing DBP and SBP were not statistically significantly different between the sibutramine group and the placebo group at any post-baseline visit during the 12-week trial. At week 12, mean increases from baseline supine SBP and DBP, respectively, were 1.6 and 1.7 mm Hg for the sibutramine group vs increases of 0.4 and 1.3 mm Hg for the placebo group. At week 12, mean increases from baseline standing SBP and DBP, respectively, were 1.5 and 1.8 mm Hg for the sibutramine group vs an increase of 0.3 and a decrease of 0.8 mm Hg for the placebo group (P > 0.05 for treatment comparison). A statistically significant mean increase of 5.6 bpm (+/-8.25, s.d.) in supine PR from a baseline of 62 bpm was reported in sibutramine-treated patients at week 12, whereas placebo-treated patients had a mean supine PR decrease of 2.2 bpm (+/-6.43) (P < 0.001). In summary, sibutramine was well tolerated and effective in weight reduction. The addition of sibutramine did not result in an increase in BP in obese patients whose hypertension was well controlled by a beta-blocker. However, based on the potential for changes in BP and PR, obese patients being treated with sibutramine should be monitored periodically for changes in BP and PR and managed appropriately.

Pharmacokinetics and tolerability of buspirone during oral administration to children and adolescents with anxiety disorder and normal healthy adults

A 21-day, open-label, multisite, dose escalation study comprising three demographic groups (children, adolescents, and adults) was performed to determine the pharmacokinetics and tolerability of orally administered buspirone. Thirteen children and 12 adolescents with anxiety disorder and 14 normal healthy adults were escalated from 5 to 30 mg buspirone bid over the 3-week study. Pharmacokinetic analysis revealed that buspirone was rapidly absorbed in all study groups, reaching peak levels at about 1 hour after administration. Peak plasma buspirone concentrations (Cmax) were highest in children and lowest in adults at all three dose levels (7.5, 15, 30 mg bid). However, 1-pyrimidinylpiperazine (1-PP), the primary metabolite of buspirone, exhibited a different plasma concentration-time profile; Cmax was significantly higher in children than in either adolescents or adults at all concentrations. In addition, TAUC0-T for 1-PP was significantly higher in the children cohort relative to adolescents and adults. Buspirone was generally safe and well tolerated at doses up to 30 mg bid in adolescents and adults and most of the children. The most frequently reported adverse events in children and adolescents were lightheadedness (68%), headache (48%), and dyspepsia (20%); 2 children withdrewfrom the study at the higher doses (15 mg and 30 mg bid) due to adverse effects. In adults, the most common adverse effect was somnolence (21.4%); lightheadedness, nausea, vomiting, and diarrhea were also reported, although these were mild in intensity.

Pharmacokinetic-pharmacodynamic modeling of rivastigmine, a cholinesterase inhibitor, in patients with Alzheimer's disease

Rivastigmine is a cholinersterase inhibitor approved recently for the treatment of Alzheimer's disease (AD). The objective of this study is to characterize the pharmacokinetics-pharmacodynamics of rivastigmine in patients with AD. Eighteen AD patients received doses ranging from 1 to 6 mg bid for about 11 weeks. Rivastigmine and its active (major) metabolite (ZNS 114-666, also called NAP 226-90), plasma, and cerebrospinal fluid (CSF) concentrations were determined together with the AChE activity and computerized neuropsychological test battery (CNTB) scores. Nonlinear mixed-effects modeling of pharmacokinetic and pharmacodynamic data was conducted using NONMEM. Rivastigmine and its metabolite exhibited dose-disproportional pharmacokinetics. The apparent clearance and volume of distribution (plasma) of rivastigmine were estimated to be 120 L/h and 236 L, respectively. The relative bioavailability at the 6 mg dose was about 140%. The metabolite had a clearance of about 100 L/h and a volume of distribution of 256 L. The kinetics of the parent and metabolite in CSF showed an equilibration half-life of about 0.2 and 0.5 hours, respectively. The metabolite levels in CSF correlated very well with the acetylcholinesterase inhibition, with a ZNS 114-666 concentration of about 5.4 microg/L required for half-maximal inhibition of acetylcholinesterase activity. No statistically significant correlation of the CNTB scores with enzyme inhibition, parent or metabolite concentration (plasma/CSF), or rivastigmine dose could be established. The PK-PD model presented in this study can provide valuable information to optimize the drug development of rivastigmine and other related compounds and also in rationalizing dosing recommendations.

Pharmacokinetics and pharmacodynamics of the triptan antimigraine agents: a comparative review

The current approach to antimigraine therapy comprises potent serotonin 5-HT1B/1D receptor agonists collectively termed triptans. Sumatriptan was the first of these compounds to be developed, and offered improved efficacy and tolerability over ergot-derived compounds. The development of sumatriptan was quickly followed by a number of 'second generation' triptan compounds, characterised by improved pharmacokinetic properties and/or tolerability profiles. Triptans are believed to effect migraine relief by binding to serotonin (5-hydroxy-tryptamine) receptors in the brain, where they act to induce vasoconstriction of extracerebral blood vessels and also reduce neurogenic inflammation. Although the pharmacological mechanism of the triptans is similar, their pharmacokinetic properties are distinct. For example, bioavailability of oral formulations ranges between 14% (sumatriptan) and 74% (naratriptan), and their elimination half-life ranges from 2 hours (sumatriptan and rizatriptan) to 25 hours (frovatriptan). Clearly, such diverse pharmacokinetic properties will influence the effectiveness of the compounds and favour the prescription of one over another in different patient populations. This article reviews the pharmacological properties of the triptans (time to peak plasma concentration, half-life, bioavailability and receptor binding) and relates these properties to efficacy and time of onset. It also considers the effects of concomitant medication, food, age and disease on the pharmacokinetics of the compounds. In addition, the relative merits, such as headache recurrence, tolerability and route of administration, are discussed. Finally, the performance of the triptans is considered in the context of direct head-to-head comparative trials that have assessed the efficacy profile of the compounds.

Safety and efficacy of PNU-142633, a selective 5-HT1D agonist, in patients with acute migraine

In this randomized, double-blind, placebo-controlled, parallel-group study, patients received a single 50-mg oral dose of a 5-HT(1D) agonist, PNU-142633 (n = 34), or matching placebo (n = 35) during an acute migraine attack. No statistically significant treatment effects were observed at 1 and 2 h after dosing, even after stratifying by baseline headache intensity. At 1 and 2 h post-dose, 8.8% and 29.4% of the PNU-142633 group, respectively, and 8.6% and 40.0% of the placebo group, respectively, experienced headache relief; 2.9% and 8.8% of the PNU-142633 group and 0% and 5.7% of the placebo group were free of headache pain. Adverse events associated with PNU-142633 treatment included chest pain (two patients) and QTc prolongation (three patients). Results from this study suggest that anti-migraine efficacy is not mediated solely through the 5-HT(1D) receptor subtype, although this receptor may contribute, at least in part, to the adverse cardiovascular effects observed with 5-HT agonist medications.

Pharmacokinetic studies of antipsychotics in healthy volunteers versus patients

In clinical trials of dopamine-blocking antipsychotics, significant adverse events may occur in healthy volunteers at dose levels that are well tolerated by schizophrenic patients. Because of these differences in tolerability, bioequivalence and pharmacokinetic studies of antipsychotics should be performed in schizophrenic patients rather than in healthy volunteers. When clozapine is the drug being investigated, pharmacokinetic and bioequivalence studies should be carried out in real-life dosage conditions because the half-life of clozapine increases with multiple doses. Under real-life conditions, the evaluation of multiple doses of clozapine in a population of schizophrenic patients can provide direct therapeutic relevance to bioavailability findings. This article discusses patient recruitment and informed consent in pharmacokinetic trials of schizophrenia, issues in studying antipsychotic agents in healthy volunteers versus schizophrenic patients, and a bioequivalency study of Clozaril (Novartis Pharmaceuticals) and generic clozapine (Creighton [Sandoz]) in schizophrenic patients.

The status of ongoing trials for mild cognitive impairment

Mild cognitive impairment (MCI) is a term used to describe memory decline or other specific cognitive impairment in individuals who do not have dementia or significant impairment of other cognitive functions beyond that expected for their age or education. It has been suggested that as much as 38% of the elderly population would meet criteria for MCI and although the associated memory deficits are mild, the fact that up to 15% of MCI patients, particularly those with a particular type of memory impairment, convert to Alzheimer's disease (AD) annually has prompted serious attention. Despite the high conversion rate, MCI cannot be used synonymously with early or mild AD, as patients with AD are impaired not only in memory performance but in other cognitive domains as well; they meet diagnostic criteria for dementia. However, since there is a high conversion rate from MCI to AD, it is likely many with MCI have the underlying neuropathology of AD, though they do not yet meet clinical diagnostic criteria. Therefore, treatment strategies developed for AD, specifically acetylcholinesterase inhibitors and Cox-2 inhibitors, have been among the first employed to treat MCI. It is hoped that by impeding the progression of MCI in this manner, fewer patients will convert to AD. This article will give a brief overview of the condition of mild cognitive impairment and an account of trial methodology and current treatment strategies being employed for MCI.

Beta-amyloid therapies in Alzheimer's disease

Neurones in the brain produce beta-amyloid fragments from a larger precursor molecule termed the amyloid precursor protein (APP). When released from the cell, these protein fragments may accumulate in extracellular amyloid plaques and consequently hasten the onset and progression of Alzheimer's disease (AD). A beta fragments are generated through the action of specific proteases within the cell. Two of these enzymes, beta- and gamma-secretase, are particularly important in the formation of A beta as they cleave within the APP protein to give rise to the N-terminal and C-terminal ends of the A beta fragment, respectively. Consequently, many researchers are investigating therapeutic approaches that inhibit either beta- or gamma-secretase activity, with the ultimate goal of limiting A beta; production. An alternative AD therapeutic approach that is being investigated is to employ anti-A beta antibodies to dissolve plaques that have already formed. Both of these approaches focus on the possibility that accrual of A beta leads to neuronal degeneration and cognitive impairment characterised by AD and test the hypothesis that limiting A beta deposition in neuritic plaques may be an effective treatment for AD.

Review of the next generation of Alzheimer's disease therapeutics: challenges for drug development

1. AD is believed to stem from dysfunctional cholinergic signaling in the regions of the brain associated with memory and cognition. 2. The occurrence of AD in afflicted individuals correlates with an increase in the accumulation of A beta-rich senile plaques and neurofibrillary tangles in the brain. 3. Currently, the only FDA-approved AD therapies are a group of acetylcholinesterase inhibitors which slow the turnover of the neurotransmitter acetylcholine in the synapse. 4. Many other compounds which target other aspects of the disease, such as reducing neuronal damage and limiting oxidation, are in clinical trials. These include monoamine oxidase (MAO-B) inhibitors, NSAIDs, antioxidants and estrogen, among others. 5. Recent research discoveries have more completely defined the molecular nature of AD, and are generating new approaches for treatment. One idea is to limit the ability of the protein tau to become phosphorylated in hopes that this will limit the formation of neurofibrillary tangles in the brain. 6. A separate approach that is being pursued is to prevent formation and accumulation of A beta plaques. This may be accomplished by either regulating gamma-secretase activity, or using anti-beta-amyloid antibodies to reduce the size of existing plaques. 7. Employing improved procedural and technological approaches during clinical trials, such as bridging studies, dynabridge studies and PET analysis, promises to streamline the drug development process. 8. The use of biomarkers and MRI analysis may be an effective means by which to identify the disease early. Consequently, early intervention treatment therapies may be an effective way of delaying onset of the disease. 9. Long term AD studies, particularly those focusing on the MCI population, are likely to provide statistically valid results using a smaller study population.

Women's health care during the perimenopause

OBJECTIVE

To review the perimenopause, its associated symptoms, and current management options.

DATA SOURCES

Published articles identified through MEDLINE (1966-2000) using the search terms perimenopause and treatment. Additional articles and books were identified from the bibliographies of the retrieved articles.

DATA SYNTHESIS

The perimenopause is the transition period from normal ovulatory cycles to menopause. It is associated with erratic fluctuations in reproductive hormone levels, often leading to irregular menstrual cycles, vasomotor symptoms, changes in mood or cognition, and sexual dysfunction. The perimenopause is an ideal time to evaluate a woman's health risks for such common chronic midlife conditions as heart disease, osteoporosis, and some cancers, and to initiate appropriate preventive health measures. Low-dose oral contraceptives and other hormonal therapies are often effective in managing perimenopausal symptoms.

CONCLUSION

The transition to menopause is an important time in the female life span that is associated with varied physical and psychological symptoms. Pharmacists should be prepared to provide education about the perimenopause and counsel women on the benefits and risks of various pharmacologic and nonpharmacologic treatments that can ease their passage through this often difficult transition. Pharmacists also are well-positioned to educate and encourage perimenopausal women to initiate lifestyle changes that can enhance their health for the rest of their lives.

Review of the acetylcholinesterase inhibitor galanthamine

Galanthamine (or galantamine, Reminyl) is a tertiary alkaloid acetylcholinesterase inhibitor (AChEI) which has been approved in several countries for the symptomatic treatment of senile dementia of the Alzheimer's type. Derived from bulbs of the common snowdrop and several Amaryllidaceae plants, (-)-galanthamine (GAL) has long been used in anaesthetics to reverse neuromuscular paralysis induced by turbocurarine-like muscle relaxants and more recently, has been shown to attenuate drug- and lesion-induced cognitive deficits in animal models of learning and memory. GAL directly inhibits acetylcholinesterase activity, while demonstrating much weaker activity on butyrylcholinesterase (BuChE). GAL also stimulates pre- and postsynaptic nicotinic receptors, although the clinical significance of this finding is yet unclear. Numerous variants and analogues of GAL have also been developed, with varying potency in inhibiting AChE activity. GAL is readily absorbed after oral administration, with a t(max) of 52 min and a plasma elimination t(1/2) of 5.7 h. The efficacy of GAL administered to Alzheimer's disease (AD) patients has been well demonstrated by large-scale clinical trials. Typical of AChEIs, the most common adverse events associated with GAL are nausea and vomiting. In conclusion, evidence to date suggests galanthamine to be similar to other AChEIs in improving cognitive function in AD patients.

RBC cholinesterase inhibition: a useful surrogate marker for cholinesterase inhibitor activity in Alzheimer disease therapy?

Red blood cell (RBC) acetylcholinesterase (AChE) inhibition has been used as a peripheral surrogate marker for the activity of centrally acting AChE inhibitors (AChEIs) in the treatment of Alzheimer disease. As a valid peripheral surrogate marker, RBC AChE inhibition should reflect the central pharmacodynamic activity of the compound and should demonstrate a relation with cognitive or global improvement in patients with Alzheimer disease. As a useful clinical tool, RBC AChE inhibition should also provide an advantage in dose optimization. However, the application of surrogate markers in research and clinical use is controversial (Prentice, 1989; Gotzsche, 1996; Colburn, 1997; De Gruttola et al., 1997). For instance, surrogate markers that have been identified or applied inappropriately can lead to erroneous conclusions, slowing the drug development process (Colburn, 1997). Also, the validation of surrogate markers for the pharmacodynamic activity of central nervous system drugs is not always possible because samples of brain tissue cannot be analyzed in humans. Finally, although validation of peripheral markers for central nervous system drugs has been approached via analysis of cerebrospinal fluid (Cutler et al., 1998a), few markers have been subjected to such rigorous evaluation in clinical studies. The extent to which measures of peripheral AChE inhibition accurately model central drug activity and therapeutic effectiveness of AChEIs, both as individual agents and as a drug class, is the focus of this review. AChEIs comprise a group of structurally diverse compounds with a wide range of relative specificities for the various molecular species of cholinesterase found in plasma, RBCs, and the brain. Studies of RBC AChE inhibition after administration of AChEIs in animals are of limited utility because of the differential sensitivity of AChEIs for human versus animal forms of AChE, the poor correlation between effective doses in animals and humans, and the lack of standardized measurements of effectiveness. Although clinical studies of donepezil, metrifonate, and eptastigmine have suggested the potential use of RBC AChE inhibition as a predictor of clinical response, the degree of inhibition yielding maximum cognitive improvements was highly variable from compound to compound (30-80%). Further, investigators did not prove a relation between central and peripheral pharmacodynamics or demonstrate an advantage over dose in the ability of RBC AChE inhibition to predict clinical response. A study of rivastigmine in patients with Alzheimer disease revealed that cerebrospinal fluid AChE inhibition correlated well with cognitive performance, whereas peripheral inhibition did not. Therefore, RBC cholinesterase inhibition is not a reliable surrogate marker for the activity of AChEIs as a class of drugs, and its usefulness as a dose optimization tool for individual agents has yet to be demonstrated clearly.

Mild cognitive impairment: emerging therapeutics

OBJECTIVE

To present a general overview of the etiology, definition, and prevalence of mild cognitive impairment (MCI), as well as outline possible treatment strategies.

DATA SOURCES

A MEDLINE search was conducted for relevant references generated from 1990 to 2000 concerning MCI, mild to moderate Alzheimer disease (AD), and therapeutic strategies. Several books were also used in the compilation of data for this review, as well as the authors' experience in designing and conducting MCI trials.

DATA EXTRACTION

All of the references listed were assessed, and all relevant information was included in this review.

DATA SYNTHESIS

Forgetful individuals most likely to develop AD have a condition known as MCI previous to their development of dementia. This condition is hallmarked by memory impairment that is abnormal for the individual's age and educational level. While not all individuals with MCI develop AD, it is apparent that the condition can serve as a potential marker for early onset of AD.

CONCLUSIONS

As many clinicians can attest, occasional forgetfulness is a common aspect of the aging process. Eventually, however, a large portion of forgetful individuals, especially those with MCI, will be diagnosed with AD or some other form of dementia. Indeed, many researchers have suggested that MCI should be regarded as incipient AD and that these individuals would benefit from drug therapy. Thus, MCI screening may be beneficial in terms of both early AD intervention and perhaps even AD prevention.

Meta-analysis of the safety and tolerability of two dose regimens of buspirone in patients with persistent anxiety

Buspirone is an azapirone with 5-HT1A partial agonist activity which has demonstrated efficacy in the treatment of generalized anxiety disorder, commonly referred to as persistent anxiety. In this meta-analysis report, safety results from two studies comparing buspirone 15 mg twice daily (BID) with buspirone 10 mg three times daily (TID) in patients with persistent anxiety are presented. In the study protocols, qualified patients completed a 7-day placebo lead-in phase and were randomized to receive buspirone 30 mg per day, as either a BID or TID regimen, for 6-8 weeks. A total of 289 patients received buspirone 15 mg BID (n = 144) or 10 mg TID (n = 145) at 15 sites. The incidence of adverse events was similar between the two treatment groups, except for a significantly greater incidence of palpitations in patients receiving buspirone BID (5%) compared to buspirone TID (1%). The most frequently reported adverse events for both buspirone BID- and TID-treated patients were dizziness, headache, and nausea. No appreciable differences between treatments were observed for vital signs, physical exam, ECG, or clinical laboratory results. A change to BID dosing for buspirone may offer convenience and possibly higher compliance in patients with persistent anxiety without compromising the excellent safety and tolerability profile of the medication.

Ongoing trials in Alzheimer's disease

Researchers have sought to understand the underlying pathophysiology of Alzheimer's disease (AD) ever since Dr A Alzheimer first described the condition in 1907. Unfortunately however, until recently, they have done so with limited success. This lack of clarity has deterred advancements in therapeutic drug research beyond all but the purely symptomatic treatment relief currently available. However, through spatio-temporal analysis of the two types of cerebral lesions that characterise the disorder (senile plaques and neurofibrillary tangles) and the compilation of genetic data concerning familial AD, there now exists the foundation for a more comprehensive understanding of the disease. Although symptomatic cholinergic strategies have beneficial effects, their benefits are modest and current research has turned to the development of other promising strategies, including oestrogen replacement, anti-inflammatory agents, free radical scavengers, anti-oxidants and monoamine oxidase-B (MAO-B) inhibitors. Many of these strategies may have some merit, however further analysis and structured research are necessary before a definitive decision can be made about their efficacy and possible role in AD therapy. Strategies that are directed at halting the underlying biochemical changes in AD are nearing clinical testing and offer the promise for meaningful therapeutic outcomes.

Gender differences in depression and antidepressant pharmacokinetics and adverse events

OBJECTIVE

To review data generated by studies examining gender differences in the prevalence of depression, as well as in antidepressant pharmacokinetics, pharmacodynamics, and adverse events.

DATA SOURCES

Published articles and abstracts were identified through MEDLINE (January 1966-April 1999) using the following search terms: antidepressant, response, gender, pharmacokinetic, pharmacodynamic, female, side effect, and adverse events. All articles that assessed gender differences in antidepressant response, pharmacokinetics, and adverse events, as well as articles that evaluated postulated mechanisms for these differences, were reviewed. Additional articles were identified from bibliographies of retrieved articles.

STUDY SELECTION AND DATA EXTRACTION

All relevant abstracts, studies, and review articles were evaluated.

DATA SYNTHESIS

Gender differences in the prevalence of depression have been reported and may result from the interaction of several factors. Women have been shown to have a higher incidence of depression, which may be due to artifact, social, or biologic reasons. Studies suggest that the pharmacokinetic disposition of popular antidepressants varies between men and women, and women taking antidepressants may exhibit a different adverse event profile. Only one study specifically evaluated gender differences in antidepressant treatment response.

CONCLUSIONS

Further research elucidating gender differences in response to antidepressant treatment and on depression prevalence is needed. Some studies report that the pharmacokinetics of antidepressants may vary between men and women. Therefore, clinicians should be aware that potential differences in antidepressant pharmacokinetics may exist, and a dosage adjustment may be necessary for women to ensure a favorable drug response, compliance, and decreased incidence of adverse events.

A bridging study of fananserin in schizophrenic patients

Fananserin is a potential antipsychotic compound with high affinity for both D4 and 5-HT2A receptors, and negligible affinity for D2 receptors. Because the tolerance for antipsychotic compounds often differs between schizophrenic patients and healthy subjects, this bridging study was designed to evaluate the tolerability of fananserin, to define the slow titration maximum tolerated dose in the target population, and to identify the most rapid well-tolerated rate of titration for this compound. Three rates of titration regimens were examined in a total of 26 schizophrenic patients in a parallel group design, following a 3-day placebo washout period from previous antipsychotic medication. The slow rate of titration (reaching the maximum dose of 600 mg/day in 16 days with 100-mg increases every 3 days) was well tolerated, but a rapid titration schedule (reaching 600 mg/day in 8 days with 200-mg increases every 3 days) resulted in hypotension in 3 of 6 patients and termination of the group on Day 10. An intermediate rate of titration (reaching 600 mg/day in 10 days with 100-mg increases every 2 days) was then examined and was well tolerated, with transient episodes of mild hypotension reported in 2 of 10 patients. Thus, although hypotension was identified as the dose-limiting adverse event in this study, a reduction in the titration rate was effective in reducing the incidence and severity of this side effect. In this study, schizophrenic patients administered multiple doses of fananserin tolerated doses 400 percent greater than the maximum tolerated single dose in healthy volunteers.

Recent developments in the drug treatment of Alzheimer's disease

Alzheimer's disease (AD) is a chronic neurodegenerative disorder with an impact on public health which continues to increase with the increasing longevity of the population. The disease is characterised clinically by a progressive loss of cognitive and behavioural function. These deficits are thought to result from decreased cholinergic transmission; therefore, restoring cholinergic function has been the main focus in the development of drugs for AD. Several pharmacological approaches to enhancing cholinergic function have been developed for symptomatic or palliative therapy of AD. Although these strategies have resulted in modest cognitive and behavioural improvements in patients with AD, they do not address the underlying progression of the disease. New strategies will be required to slow, stop or reverse the effects of neurodegeneration in AD. A number of potential therapies are currently under investigation, including estrogen replacement, anti-inflammatory agents, free radical scavengers and antioxidants, and monoamine oxidase-B (MAO-B) inhibitors. The evidence for a protective effect of estrogens or nonsteroidal anti-inflammatory drugs (NSAIDs) is controversial, and largely based on retrospective studies. More controlled prospective studies are needed to definitively demonstrate the benefits of long term estrogen or NSAID use in the prevention of AD. Free radical scavengers/antioxidants such as idebenone, and selective prevention MAO-B inhibitors such as lazabemide are well tolerated, but require additional studies in order to demonstrate preventative effects. In addition, other approaches, such as anti-amyloid treatments that affect beta-amylase secretion, aggregation and toxicity, appear promising; treatments that hinder neurofibrillary tangle construction and nerve growth factor (NGF) induction are in the very early stages of development.

NXX-066 in patients with Alzheimer's disease: a bridging study

Reduced cholinergic transmission is a key neurotransmitter dysfunction in Alzheimer's Disease (AD). NXX-066, a physostigmine analog and acetylcholinesterase (AChE) inhibitor, has demonstrated activity in animal models of memory function, and was well tolerated in healthy subjects up to a single dose of 64 mg and multiple doses of 60 mg QD for seven days. Since AChE inhibitors are often tolerated differently in AD patients than in healthy volunteers, a randomized, placebo-controlled, double-blind, single-center, inpatient bridging study was conducted to determine the maximum tolerated dose (MTD) of NXX-066 in the target patient population. Seven consecutive panels of eight AD patients each (6 active, 2 placebo) received fixed oral doses of NXX-066 (20, 30, 40, 50, 60, 70, or 80 mg BID) for seven days. Initiation of each subsequent panel (dose group) was contingent upon the tolerability of lower dose levels. The MTD was determined to be 70 mg BID when four of six patients receiving 80 mg BID were prematurely discontinued from the study due to nausea and/or vomiting, accompanied in some patients by mild to moderate dizziness, headache, asthenia, and gastric symptoms. Wide variability in plasma levels of NXX-066 was observed in all dose panels. AChE inhibition in whole blood correlated with both maximum plasma concentration and dose; however, AChE inhibition was not predictive of adverse events. In this study, AD patients tolerated larger daily doses of NXX-066 on a BID regimen than healthy normal subjects had tolerated with QD dosing. Further studies are warranted to examine whether differing tolerability between patients and healthy subjects or the reduced dosing interval explains these findings.

Pharmacokinetics of Rizatriptan Tablets During and Between Migraine Attacks

Gastric stasis during migraine attacks results in delayed absorption of several orally administered antimigraine agents. This study, as part of a larger trial, was conducted to examine the pharmacokinetics of rizatriptan tablets during and between migraine attacks. Participating patients met IHS criteria for migraine with or without aura, and suffered between one and eight migraines per month for the previous 6 months. In part 1 of the study, 21 patients were randomized to receive a single 5-mg tablet of rizatriptan or placebo in the migraine-free state. In part 2, the same patients were treated during migraine with rizatriptan 5-mg tablets (n=18) or placebo (n=3). Blood samples were obtained before dosing and 0.25, 0.5, 0.75, 1, 1.5, 2, 3, 4, 6, 8, and 12 hours after dosing. The plasma concentration profile (ie, AUC((0-infinity)), C(max), T(max)) of rizatriptan 5-mg tablets administered during and between migraine attacks were comparable. The median T(max) for rizatriptan between and during attacks was 1 hour, indicating rapid absorption even during a migraine attack. Rizatriptan 5 mg was well tolerated and 67% of the patients experienced headache relief 2 hours postdose.

Cholinesterase inhibitors: a therapeutic strategy for Alzheimer disease

OBJECTIVE

To provide a review of acetylcholinesterase inhibitors (AChEIs) tested as therapeutic agents for Alzheimer disease (AD).

DATA SOURCES

MEDLINE searches (January 1986-July 1998) identified pertinent literature. Selected references from these articles, as well as abstracts from recent meetings and package insert literature from approved compounds, were also used as source material.

DATA EXTRACTION

AChEIs were reviewed with regard to chemical structure, mechanism of inhibition, substrate specificity, pharmacokinetics/pharmacodynamics, safety/tolerability, and efficacy.

DATA SYNTHESIS

Cholinergic deficits, leading to cognitive impairment, are a significant aspect of neurodegeneration in AD. AChEIs reduce the degradation of acetylcholine, thus enhancing cholinergic transmission. In addition to the two agents approved by the Food and Drug Administration, tacrine and donepezil, six other compounds of diverse chemical structure and mechanism of inhibition including physostigmine, metrifonate, rivastigmine, and galantamine are under investigation as potential therapy for AD. These compounds are structurally diverse, possess unique patterns of specificities for the various forms of cholinesterase enzymes, use distinct mechanisms of enzyme inhibition, present unique adverse event profiles, and offer relatively similar mean gains in cognitive abilities to patients with AD in controlled clinical trials.

CONCLUSIONS

Relative to placebo, new AChEIs in development provide modest improvements in cognition for patients with mild to moderate AD, with improved tolerability profiles and more convenient dosing relative to tacrine. The availability of a wide array of AChEIs soon to be accessible to patients with AD will provide additional options to those who cannot tolerate or do not respond to drugs currently used for AD.

A double-blind, randomized, crossover assessment of blood pressure following administration of avitriptan, sumatriptan, or placebo to patients with mild to moderate hypertension

We examined the effects of avitriptan, a 5-hydroxytryptamine 1-like (5HT1) receptor agonist for the treatment of migraine, in patients with medicated, controlled, mild to moderate hypertension relative to placebo and sumatriptan. The study was randomized, double-blinded, placebo-controlled, and 4-way crossover in design. Twenty patients (12M, 8F) participated. As required by protocol, all were stable on medications for mild to moderate hypertension, with a supine diastolic blood pressure of < 95 mmHg. Qualified subjects were randomized to receive oral administration of either 75 or 150 mg of avitriptan, 100 mg sumatriptan or placebo during the four treatment visits. Supine blood pressure and pulse rates were recorded up to 24 h after drug administration. Avitriptan 150 mg significantly increased peak diastolic and systolic blood pressure, and mean arterial pressure compared to placebo and sumatriptan 100 mg (p < 0.05). Only those hypertensive patients receiving medication for hypertension should receive anti-migraine medications, such as avitriptan, which are 5HT1-like receptor agonists.

Exploratory studies: implications for drug development in Alzheimer's disease

The process of drug development involves cycles of learning and confirming. In the learning phase of the cycle, data from studies are used to generate hypotheses; later studies are designed specifically to confirm these hypotheses. There is a growing realization that exploratory studies early in drug development are critical for the design of large confimatory clinical trials. For example, patients often differ from healthy volunteers in their tolerance of CNS compounds, so investigators should determine the maximum tolerated dose (MTD) in the patient population though a "bridging study" prior to designing Phase II efficacy trials. By performing well-controlled safety/tolerability studies with a small number of patients on an inpatient basis, researchers can avoid exposing large numbers of study participants to the wrong dose. Bridging studies also provide information on the approximate frequencies of various types of adverse events, which is very helpful in designing outpatient trials to confirm the safety profile. A second type of exploratory study, a "dynabridge study", is an early pharmacokinetic/pharmacodynamic (PK/PD) study in patients to measure drug concentrations and activities in the central compartment (assessed by sampling the CSF). Dynabridge studies can be used to optimize the dosing regimen, to confirm that the drug is affecting the targeted receptor, and to measure correlations between drug activity and proposed surrogate markers.

Efficacy of xanomeline in Alzheimer disease: cognitive improvement measured using the Computerized Neuropsychological Test Battery (CNTB)

The cognitive efficacy of the M1-selective muscarinic agonist xanomeline in mild-to-moderate Alzheimer disease (AD) was measured using the Computerized Neuropsychological Test Battery (CNTB) and the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-cog) in this 17-center, double-blind, placebo-controlled study. Three hundred forty-three patients were randomly assigned to receive 25, 50, or 75 mg xanomeline tartrate or placebo three times daily (t.i.d.) for 24 weeks, followed by placebo for 4 weeks in a single-blind washout phase. Cognitive function was assessed at randomization and after 4, 8, 12, 24, and 28 weeks. Three hundred nineteen patients were included in an intent-to-treat (ITT) analysis; 209 completers had evaluable data at week 24. ITT analysis showed a significant (p < or = 0.05) dose-response trend and a significant (p < or = 0.05) between-group comparison favoring 75 mg t.i.d. over placebo for the CNTB summary score but not for the ADAS-cog. In the completer analysis, however, the ADAS-cog showed a significant (p < or = 0.05) dose-response trend and between-group comparison, whereas the CNTB Summary Score did not. The ADAS-cog was less sensitive to treatment effects in mildly impaired patients (ADAS-cog < 21) than in moderately impaired patients (ADAS-cog > or = 21), whereas the CNTB was sensitive in the entire study population (mean ADAS-cog = 22.5+/-9.6). Significant (p < or = 0.05) beneficial treatment effects were seen in measures of simple reaction time and delayed verbal recall, which are included in the CNTB but not in the ADAS-cog. During the single-blind placebo washout period, the ADAS-cog score of the placebo group worsened dramatically (change of 2.63 points; p < or = 0.001), whereas the CNTB score remained stable (change of 1.04 points; p=0.694). Thus, the CNTB appears to be more objective than the ADAS-cog.

Sertraline in children and adolescents with obsessive-compulsive disorder: a multicenter randomized controlled trial

CONTEXT

The serotonin reuptake inhibitors are the treatment of choice for patients with obsessive-compulsive disorder; however, empirical support for this assertion has been weaker for children and adolescents than for adults.

OBJECTIVE

To evaluate the safety and efficacy of the selective serotonin reuptake inhibitor sertraline hydrochloride in children and adolescents with obsessive-compulsive disorder.

DESIGN

Randomized, double-blind, placebo-controlled trial.

PATIENTS

One hundred eighty-seven patients: 107 children aged 6 to 12 years and 80 adolescents aged 13 to 17 years randomized to receive either sertraline (53 children, 39 adolescents) or placebo (54 children, 41 adolescents).

SETTING

Twelve US academic and community clinics with experience conducting randomized controlled trials.

INTERVENTION

Sertraline hydrochloride was titrated to a maximum of 200 mg/d during the first 4 weeks of double-blind therapy, after which patients continued to receive this dosage of medication for 8 more weeks. Control patients received placebo.

MAIN OUTCOME MEASURES

The Children's Yale-Brown Obsessive Compulsive Scale (CY-BOCS), the National Institute of Mental Health Global Obsessive Compulsive Scale (NIMH GOCS), and the NIMH Clinical Global Impressions of Severity of Illness (CGI-S) and Improvement (CGI-I) rating scales.

RESULTS

In intent-to-treat analyses, patients treated with sertraline showed significantly greater improvement than did placebo-treated patients on the CY-BOCS (adjusted mean, -6.8vs -3.4, respectively; P=.005), the NIMH GOCS (-2.2 vs -1.3, respectively; P=.02), and the CGI-I (2.7 vs 3.3, respectively; P=.002) scales. Significant differences in efficacy between sertraline and placebo emerged at week 3 and persisted for the duration of the study. Based on CGI-I ratings at end point, 42% of patients receiving sertraline and 26% of patients receiving placebo were very much or much improved. Neither age nor sex predicted response to treatment. The incidence of insomnia, nausea, agitation, and tremor were significantly greater in patients receiving sertraline; 12 (13%) of 92 sertraline-treated patients and 3 (3.2%) of 95 placebo-treated patients discontinued prematurely because of adverse medical events (P=.02). No clinically meaningful abnormalities were apparent on vital sign determinations, laboratory findings, or electrocardiographic measurements.

CONCLUSION

Sertraline appears to be a safe and effective short-term treatment for children and adolescents with obsessive-compulsive disorder.

Distinct mechanism for antidepressant activity by blockade of central substance P receptors

The localization of substance P in brain regions that coordinate stress responses and receive convergent monoaminergic innervation suggested that substance P antagonists might have psychotherapeutic properties. Like clinically used antidepressant and anxiolytic drugs, substance P antagonists suppressed isolation-induced vocalizations in guinea pigs. In a placebo-controlled trial in patients with moderate to severe major depression, robust antidepressant effects of the substance P antagonist MK-869 were consistently observed. In preclinical studies, substance P antagonists did not interact with monoamine systems in the manner seen with established antidepressant drugs. These findings suggest that substance P may play an important role in psychiatric disorders.

Guidelines for conducting bridging studies in Alzheimer disease

This report provides guidelines for conducting bridging studies in patients with Alzheimer disease (AD). Bridging studies are late phase I safety/tolerance studies that determine the maximum tolerated dose (MTD) in patients before phase II efficacy studies are initiated, facilitating the transition from phase I to phase II development. Determining the MTD in patients maximizes the potential to detect efficacy by permitting the use of the highest tolerated doses in phase II while providing a good understanding of potential adverse events. Bridging studies should be double-blind, placebo-controlled, inpatient studies conducted in acute-care facilities by clinical personnel who are equipped to handle unexpected contingencies under the oversight of a competent, multidisciplinary review board. Patients should be in good physical health (excluding AD), and a comprehensive informed consent procedure must be instituted. We recommend initially using a fixed-dose panel design with a dose schedule based on the MTD in normal volunteers and later establishing the dose titration MTD.

Pharmacokinetics and pharmacodynamics of avitriptan in patients with migraine after oral dosing

Avitriptan (BMS-180048) is a 5-HT1-like receptor agonist for the treatment of migraine. This double-blind, placebo-controlled, randomized, parallel-group study evaluated the pharmacokinetics, safety, and preliminary efficacy of avitriptan in patients with migraine during migrainous and pain-free states. Patients met the IHS criteria for migraine with or without aura and suffered one to six migraines per month for at least 1 year. Patients in a clinic experiencing a migraine headache received avitriptan 75 mg, 150 mg, or 200 mg or matching placebo capsules. Blood samples were obtained before and 0.25, 0.75, 1, 1.5, 2, 2.5, 3, 4, 5, and 6 hours after dosing. Headache intensity was rated before and up to 6 hours after dosing. Seven to 30 days after the inclinic treatment, patients returned in a pain-free state for the same study medication. All pharmacokinetic and safety measures were repeated. Forty-eight patients (9 men and 39 women) participated. Peak plasma concentrations of avitriptan were achieved 1 to 2 hours following dosing in migraine and pain-free states for all doses. The pharmacokinetics of avitriptan were proportional to dose during a migraine attack over the 75- to 200-mg dose range. The 150- and 200-mg doses of avitriptan demonstrated a greater decrease in headache intensity scores at 2 hours postdose. The most common adverse event was paresthesia. Thus, avitriptan was rapidly absorbed, well tolerated, and demonstrated preliminary efficacy in this population.

Safety and tolerability of metrifonate in patients with Alzheimer's disease: results of a maximum tolerated dose study

Metrifonate, a pro-drug that is transformed non-enzymatically into a potent inhibitor of acetylcholinesterase (AChE), has been used in the tropics for over 30 years for the treatment of schistosomiasis. A pilot study, and Phase I and Phase II studies of metrifonate in Alzheimer's disease (AD) patients conducted prior to the current study showed benign, dose-dependent adverse event profiles consisting primarily of gastrointestinal events, optimal daily dosing with a loading phase (in the absence of a loading dose phase, 6-8 weeks were required to attain steady-state AChE inhibition levels), and an improvement in Alzheimer's Disease Assessment Scale (ADAS) scores. The current open-label study was designed to evaluate the safety and tolerability of relatively high loading doses, followed by lower maintenance doses of metrifonate in the same patient population, and to determine the maximum tolerated dose (MTD) of metrifonate. Accordingly, the first cohort of 8 probable AD patients (per National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association [NINCDS-ADRDA] criteria) were administered once-daily loading doses of 2.5 mg/kg (125-225 mg) for 14 days, followed by 4.0 mg/kg (200-360 mg) for an additional 3 days. These patients were maintained on once-daily doses of 2.0 mg/kg (100-180 mg) for 14 days. AChE inhibition for this cohort ranged from 88% to 94%. On Day 28 of 31, this cohort was discontinued due to moderate to severe side effects in 6 patients; consequently, the second cohort of 8 probable AD patients received a once-daily loading dose of 2.5 mg/kg (125-225 mg) for 14 days followed by a once-daily maintenance dose of 1.5 mg/kg (75-135 mg) for 35 days. This maintenance dose yielded an AChE inhibition level ranging from 89% to 91%. In spite of an AChE inhibition level comparable to that achieved with the higher dose, the reduced dose was associated with a more favorable adverse event profile which was mainly gastrointestinal and musculoskeletal in nature. The maximum tolerated dose was established at 1.5 mg/kg/day (75-135 mg/day) for maintenance dosing in AD patients.

Initial safety, tolerability pharmacodynamics, and pharmacokinetics of CI-1007 in patients with schizophrenia

CI-1007 is a novel dopamine autoreceptor agonist and partial dopamine D2/D3 agonist that is currently under development for the treatment of schizophrenia. This single-blind, rising, multiple-dose, inpatient bridging study was designed to evaluate the safety and tolerability of CI-1007 in consecutive panels of patients with schizophrenia. Following a 4-day placebo washout period, 16 patients (4 per panel) were assigned to receive one of four fixed-dosage regimens of CI-1007 (5, 10, 15, or 20 mg q12h for 9 doses). CI-1007 was generally well tolerated over the dose range evaluated. Adverse events, including mild to moderate sporadic orthostatic hypotension and/or nausea and vomiting, were most commonly observed after the initial drug dose and decreased after repeated dosing. Serum concentrations of growth hormone (GH) increased following the administration of CI-1007, confirming its central dopamine agonist activity. Changes in serum prolactin were not related to dose. The pharmacokinetics of CI-1007 and its active metabolite appear linearly related to dose. The results of this study suggest that patients with schizophrenia tolerate slightly higher initial doses of CI-1007 than do healthy subjects.

Long-term efficacy, tolerability, and safety of the combination of enalapril and felodipine ER in the treatment of hypertension. Enalapril-Felodipine ER Factorial Study Group

A recent 8-week, double-masked, placebo-controlled, 3 x 4 factorial-design study demonstrated that enalapril-felodipine extended-release (ER) combinations had statistically significant additive effects for reducing both sitting systolic blood pressure (SiSBP) and sitting diastolic blood pressure (SiDBP) and were generally well tolerated in hypertensive patients with SiDBPs ranging from 95 to 115 mm Hg. The present open-label study was undertaken to assess the long-term efficacy, tolerability, and safety of such combinations. Patients from the factorial study were eligible for the 1-year, open-label extension. Initially, all patients received enalapril 5 mg-felodipine ER 2.5 mg once daily; if SiDBP was not controlled (< 90 mm Hg) after 4 weeks of treatment, the dose was titrated upward at 2- to 4-week intervals to a maximum of enalapril 10 mg-felodipine ER 10 mg. Hydrochlorothiazide (HCTZ) 12.5 mg was added to the regimen of patients whose hypertension was not controlled at the highest enalapril-felodipine ER dose. A total of 507 patients were enrolled, of whom 502 were assessable. At their last study visit, 391 (78%) of the assessable patients were receiving only an enalapril-felodipine ER combination. The enalapril-felodipine ER combinations resulted in mean trough SiDBPs of 85 to 89 mm Hg (decreases of 13 to 16 mm Hg from baseline) and SiSBPs of 137 to 140 mm Hg (decreases of 13 to 21 mm Hg). Overall, 407 (81%) of the 502 assessable patients achieved an SiDBP < 90 mm Hg or a reduction from baseline > or = 10 mm Hg (responders); such a response was recorded in 331 patients (66%) taking a combination of enalapril-felodipine ER alone and 76 patients (15%) taking the combination with the addition of HCTZ 12.5 mg. Blood pressure reductions were maintained throughout the treatment period. Drug-related adverse events were relatively infrequent, often transient, usually mild, and apparently not dose related. The most frequently reported drug-related adverse events were edema/swelling, asthenia/fatigue, dizziness, cough, and headache. These results suggest that combination therapy with enalapril-felodipine ER is effective for long-term blood pressure reduction, has an excellent safety profile, and is generally well tolerated. Addition of low-dose HCTZ to the enalapril-felodipine ER combination appears to provide further blood pressure control without increasing drug-related adverse events.

Rizatriptan (MAXALT) for the acute treatment of migraine and migraine recurrence. A placebo-controlled, outpatient study. Rizatriptan 022 Study Group

Rizatriptan is a novel 5-HT1B/1D agonist which is rapidly absorbed after oral administration. The efficacy and tolerability of oral rizatriptan (5 mg and 10 mg) were examined in this multicenter, double-blind, outpatient study of 1473 migraineurs which featured randomized, placebo-controlled treatment of migraine recurrences. On experiencing moderate or severe migraine headaches, patients rated headache severity prior to dosing and at 30-minute intervals for 2 hours after dosing. Onset of effect was seen as early as 30 minutes after dosing with rizatriptan 10 mg. At 2 hours postdose, the percentage of patients with pain relief was significantly higher after rizatriptan 5 mg (62%) or 10 mg (71%) compared with placebo (35%). Complete relief was also significantly higher after rizatriptan 5 mg (33%) and 10 mg (42%) compared with placebo (10%). In patients experiencing headache recurrence after initial benefit, further relief was obtained in 71% with rizatriptan 5 mg (placebo 54%) and in 82% with rizatriptan 10 mg (placebo 44%). Complete relief of recurrent headache was obtained in 36% with rizatriptan 5 mg, 49% with rizatriptan 10 mg, and 15% with placebo (P < 0.05). The most common drug-related adverse experiences were dizziness, somnolence, asthenia/fatigue, and nausea (the incidences of which were low and dose related). There was no increase in the incidence of adverse experiences after use of up to three doses of rizatriptan within 24 hours. We conclude that both doses of rizatriptan are effective and well tolerated in the acute treatment of migraine and migraine recurrence, with the 10-mg dose preferred as it is more effective with a faster onset of action.

Dose-dependent CSF acetylcholinesterase inhibition by SDZ ENA 713 in Alzheimer's disease

INTRODUCTION

This study evaluates the activity of SDZ ENA 713, a centrally-selective acetylcholinesterase (AChE) inhibitor, in the cerebral spinal fluid (CSF) of patients with Alzheimer's disease (AD), and its relationship to central and peripheral pharmacokinetic parameters.

METHODS

Eighteen AD patients were enrolled in this open-label, multiple-dose study. Patients were titrated in 1 mg bid/week increments to target doses of 1, 2, 3, 4, 5, or 6 mg bid SDZ ENA 713. After patients had been maintained at their target dose for at least 3 days, continuous CSF samples were obtained via a lumbar catheter for 12.5 h, beginning 0.5 h prior to the final dose of SDZ ENA 713.

RESULTS

Dose-dependent inhibition of CSF AChE was significantly correlated (P < 0.05) with plasma drug and metabolite concentrations. The 6 mg bid treatment group showed a maximum mean inhibition of 62% at 5.6 h post-dose.

CONCLUSION

Rapid, sustained, dose-dependent inhibition of CSF AChE suggests that SDZ ENA 713 has therapeutic potential in AD patients.

A bridging study of LU 25-109 in patients with probable Alzheimer's disease

Lu 25-109 is a functionally selective partial M1 agonist with M2/M3 antagonist properties. This double-blind, placebo-controlled, two-part, inpatient bridging study was designed to evaluate the safety and tolerability of multiple oral doses of Lu 25-109 in patients with Alzheimer's Disease(AD), and to determine the maximum tolerated dose (MTD) in this population. In the first part of the study, the fixed-dose MTD was to be determined in five consecutive panels of 6 patients each (4 Lu 25-109/2 placebo). Doses for the five panels were 100, 125, 150, 200, and 225 mg tid for 7 days. Cholinergic adverse events such as increased salivation, dizziness, and gastrointestinal symptoms were observed at all doses studied. The dosing of fixed-dose panels was discontinued after 3 days at 200 mg tid due to unacceptable gastrointestinal adverse events. Thus, 150 mg tid was defined as the fixed-dose MTD. The second part of the study, conducted in a single panel of 8 patients (6 Lu 25-109/2 placebo), was designed to determine if patients could tolerate higher doses of Lu 25-109 when administered on a titration regimen. Patients were to receive doses that were 50%, 75%, 100%, 125%, and 150% of the fixed dose MTD, with dose increases every five days. The first dose, 75 mg tid, was very well-tolerated; however, as in the first phase of the study, patients did not tolerate the 200 mg tid dose. Thus, the titration regimen employed did not improve the overall tolerability of Lu 25-109.

Monitoring of acute migraine attacks: placebo response and safety data

In the course of evaluating the safety and efficacy of an investigational compound for acute migraine headaches, a large number of patients received placebo at a single site, offering the opportunity to characterize subjective and clinical physiologic responses of migraine patients to placebo in a controlled environment. In a single-site, double-blind, placebo-controlled study, 67 patients reported to the clinic while suffering a moderate to severe acute migraine headache and received oral placebo. For 6 hours after treatment, a continuous electrocardiogram (ECG) was performed, and headache severity, adverse events, and vital signs were recorded. Patients returned and repeated the procedure when free from pain. A headache was considered to be improved if its severity dropped to "mild" or "none." Twenty-five patients (37%; 95% CI: 26% to 50%) experienced headache improvement within 2 hours of receiving placebo, and 32 patients (48%: 36% to 60%) improved within 4 hours. There were no clinically important ECG changes during the migraine visit, and there were no clinically relevant differences in vital signs between the migraine and pain-free visits. Thus, a substantial placebo response occurs in migraine headache. Hemodynamic and ECG parameters are unchanged between migraine and pain-free states.

Ethnicity and antipsychotic response

OBJECTIVE

To review the data generated by studies examining interethnic/racial differences in response to antipsychotics.

DATA SOURCES

A MEDLINE search (1966-1996) identified all articles examining differences in antipsychotic response among Caucasians, Asians, Hispanics, and African-Americans, as well as articles evaluating postulated mechanisms for these differences.

STUDY SELECTION

All abstracts, studies, and review articles were evaluated.

DATA SYNTHESIS

Ethnic/racial differences in response to antipsychotic medications have been reported and may be due to genetics, kinetic variations, dietary or environmental factors, or variations in the prescribing practices of clinicians. Studies suggest that Asians may respond to lower doses of antipsychotics due to pharmacokinetic and pharmacodynamic differences. Research relevant to African-Americans is limited, but some studies suggest that differences in this group may be due to clinician biases and prescribing practices, rather than to pharmacokinetic or pharmacodynamic variability.

CONCLUSIONS

Future research directed at validating the hypotheses that different ethnic/racial groups show variations in response to antipsychotics should focus on homogeneous ethnic groups, use recent advances in pharmacogenetic testing, and control for such variables as observer bias, gender, disease chronicity, dietary and environmental factors, and exposure to enzyme-inducing and -inhibiting agents. Clinicians should be aware that potential interethnic/racial differences in pharmacodynamics and pharmacokinetics may exist that can alter response to antipsychotics.

Two rapid-dose titrations of sertindole in patients with schizophrenia

The novel antipsychotic sertindole has demonstrated efficacy in psychosis with an extrapyramidal syndrome profile indistinguishable from placebo. Prior trials of sertindole have increased the dose by 4 mg every third day, whereas the present study evaluated the safety and tolerability of two, previously untested, more rapid dose escalation regimens. Sixteen schizophrenic inpatients entered a 4-day, single-blind placebo washout period in two consecutive groups. All patients received sertindole in 4-mg dose increments up to a maximum dose of 24 mg, which was maintained for 5 days. Dose increases were every other day for group 1 (N = 8) and daily for group 2 (N = 8). Adverse events, electrocardiograms, routine laboratory tests, and plasma sertindole concentrations were recorded. No patient was discontinued because of adverse events. The most frequent adverse events were tachycardia upon orthostatic challenge, nasal congestion, dry mouth, and headache; except for dry mouth, the incidence of these was greater in group 2. All cases of tachycardia were asymptomatic. No clinically significant laboratory abnormalities were detected in either group. In conclusion, 4-mg increases of sertindole every other day seems to be safe. Daily titration was, in general, not well tolerated.

Penetration of trovafloxacin into cerebrospinal fluid in humans following intravenous infusion of alatrofloxacin

A single-dose study was conducted to determine concentrations of trovafloxacin (CP-99,219) achieved in the cerebrospinal fluid (CSF) relative to those in the serum of healthy subjects after intravenous infusion of alatrofloxacin (CP-116,517), the alanyl-alanyl prodrug of trovafloxacin. Twelve healthy subjects were administered single doses of alatrofloxacin at a trovafloxacin equivalent of 300 mg as an intravenous infusion over 1.0 h. CSF samples were taken by lumbar puncture at 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 24 h after the start of the infusion; each subject was sampled at only one time point. Serum samples were taken from each subject at the time of CSF collection. A mean concentration of 5.8 microg of trovafloxacin per ml was present in serum 1.0 h after the start of the infusion. CSF/serum ratios ranged from 0.14 to 0.33 in the postdistribution phase (5 to 24 h postinfusion), with a mean ratio of 0.25. The most common adverse events were dizziness, nausea, and rash and were mild or moderate in intensity. The potency of trovafloxacin against susceptible organisms, coupled with its rapid penetration of CSF following the intravenous administration of alatrofloxacin, suggests that it may be useful in the treatment of bacterial meningitis in humans.