Combining Antidepressants with β-Blockers: Evidence of a Clinically Significant CYP2D6 Drug Interaction

BACKGROUND

The β-blockers and antidepressants are two of the most commonly prescribed drug classes in the United States. Several antidepressants are potent inhibitors of cytochrome P450 2D6 liver enzymes (CYP2D6) and can increase the plasma concentrations of certain β-blockers when administered concomitantly, potentially leading to serious medical consequences such as hypotension, bradycardia, and falls.

OBJECTIVE

The primary objective of this investigation was to determine whether initiating an antidepressant in patients receiving β-blockers increased the risk of hemodynamic adverse events. Our primary outcome was time to hospital admissions or emergency department (ED) visits for an International Classification of Diseases-9 diagnosis suggestive of excessive β-blockade.

METHODS

We conducted a survival analysis for adults continuously enrolled in the California Medicaid system (Medi-Cal) between 2004 and 2012. Eligible patients were required to be receiving β-blocker medications that are primarily CYP2D6 substrates (e.g., metoprolol, propranolol, or carvedilol). Univariate and multivariable analyses were performed for patients who concurrently received antidepressants with β-blockers. An additional multivariable analysis analyzed the association of this combination upon hospitalizations or ED visits for all causes.

RESULTS

A total of 21,292 beneficiaries met the inclusion criteria, and 4.3% of patients required hospitalization or ED visits within 30 days of co-medication. In multivariable analysis, patients receiving antidepressants with moderate to strong CYP2D6 inhibitory potential (fluoxetine, paroxetine, duloxetine, or bupropion) had a greater risk for hospitalization or ED visits for hemodynamic events than those initiated on antidepressants with weak CYP2D6 inhibition for 30 days or less when each was compared with patients receiving no antidepressants (hazard ratio [HR] 1.53, 95% confidence interval [CI] 1.03-2.81; p=0.04 vs HR 1.24; 95% CI 0.82-1.88; p=0.30). Other demographic variables associated with increased morbidity included advanced age, male sex, higher β-blocker doses, and African American race or Hispanic ethnicity.

CONCLUSIONS

Results of this analysis suggest that initiation of certain antidepressants was associated with an increased risk for serious medical sequelae among patients concurrently receiving β-blockers. Greater risk was observed with antidepressants that potently inhibit the CYP2D6 enzyme, implying that increased morbidity may be mediated by a metabolic drug interaction.

Association between Use of Methadone, Other Central Nervous System Depressants, and QTc Interval-Prolonging Medications and Risk of Mortality in a Large Cohort of Women Living with or at Risk for Human Immunodeficiency Virus Infection

STUDY OBJECTIVE

To evaluate the association between use of methadone, other central nervous system (CNS) depressants, and QTc interval-prolonging medications and risk of mortality among human immunodeficiency virus (HIV)-infected and at-risk HIV-uninfected women.

DESIGN

Multicenter, prospective, observational cohort study (Women's Interagency HIV Study [WIHS]).

PARTICIPANTS

A total of 4150 women enrolled in the WIHS study between 1994 and 2014 who were infected (3119 women) or not infected (1031 women) with HIV.

MEASUREMENTS AND MAIN RESULTS

Data on medication utilization were collected from all study participants via interviewer-administered surveys at 6-month intervals (1994-2014). Mortality was confirmed by National Death Index data. With age defining the time scale for the analysis, Cox proportional hazards models were used to estimate hazard ratios (HRs) for all-cause mortality in HIV-infected and -uninfected women and non-acquired immunodeficiency syndrome (AIDS) deaths in HIV-infected women. A total of 1046 deaths were identified, of which 429 were considered non-AIDS deaths. Use of benzodiazepines, CNS depressants (excluding methadone), and number of medications with conditional QTc interval-prolonging effects were each associated with all-cause mortality in multivariate models of HIV-infected women: hazard ratio (HR) 1.28, 95% confidence interval (CI) 1.01-1.60, p=0.037; HR 1.61, 95% CI 1.35-1.92, p<0.0001; and HR 1.15 per drug, 95% CI 1.00-1.33, p=0.047, respectively. Other explanatory variables for all-cause mortality in this model included HIV viral load, CD4+  cell count, renal function, hemoglobin and albumin levels, HIV treatment era, employment status, existence of depressive symptoms, ever use of injection drugs, and tobacco smoking. Of interest, use of CNS depressants (excluding methadone) was also associated with non-AIDS deaths (HR 1.49, 95% CI 1.49-2.2, p<0.0001). Although use of benzodiazepines and conditional QT interval-prolonging medications were associated with increased risk of non-AIDS mortality (HR 1.32 and 1.25, respectively), the effect was not statistically significant (p>0.05).

CONCLUSION

In this cohort of HIV-infected and at-risk HIV-uninfected women, use of benzodiazepines, CNS depressants, and conditional QTc interval-prolonging medications were associated with a higher risk of mortality independent of methadone and other well-recognized mortality risk factors. Care must be taken to assess risk when prescribing these medications in this underserved and at-risk patient population.

Drug Interactions with Lithium: An Update

Lithium has been used for the management of psychiatric illnesses for over 50 years and it continues to be regarded as a first-line agent for the treatment and prevention of bipolar disorder. Lithium possesses a narrow therapeutic index and comparatively minor alterations in plasma concentrations can have significant clinical sequelae. Several drug classes have been implicated in the development of lithium toxicity over the years, including diuretics and non-steroidal anti-inflammatory compounds, but much of the anecdotal and experimental evidence supporting these interactions is dated, and many newer medications and medication classes have been introduced during the intervening years. This review is intended to provide an update on the accumulated evidence documenting potential interactions with lithium, with a focus on pharmacokinetic insights gained within the last two decades. The clinical relevance and ramifications of these interactions are discussed.

Abstract W MP110: Stimulant Medications as a Risk Factor for Childhood Stroke

Background: The association of stimulants and stroke in adults has raised concerns about attention deficit hyperactivity disorder (ADHD) medications prescribed to children. A large retrospective cohort study found no increased risk for serious cardiovascular events but was limited in how stroke was identified. We examined the association between stimulant medications and stroke in a case-control study with cases rigorously detected.

Methods: This study was nested in a cohort of 2.5 million children (<20y) enrolled in a large integrated health care plan, 1993-2007. Cases of hemorrhagic and ischemic stroke at ≥2 years of age were identified from searches of radiology reports in addition to diagnostic codes, and confirmed through independent chart review; 4 controls per case were randomly selected, matched by age, year of enrollment and primary care facility. The cohort was linked to electronic pharmaceutical records to collect data on ADHD medications prior to stroke (index date for controls). Analyses using conditional logistic regression focused on current use (at time of event), use within the past 6 months (at least 2 sequential prescriptions), and ever use. Length of most recent continuous exposure was compared between groups. Our study was powered to detect an OR as low as 4.4 for current exposure and 3.7 for 6-month exposure.

Results: We identified 258 cases and 1030 controls. No measured exposures significantly differed between the two groups in adjusted analyses (Table). The median (IQR) length of continuous exposure for those using stimulants within the prior 6 months was 322 days (100, 187) for cases and 377 days (198, 821) for controls (p=0.10).

Conclusions: No significant associations were found between stroke and use of ADHD stimulants in this study rigorously identifying pediatric stroke outcomes over a 14-year period. The OR for current use was similar to that found in a large cohort study.

A pilot study evaluating genetic and environmental factors for postpartum depression

OBJECTIVE

To assess the influence of genetic and environmental risk factors upon postpartum depression.

DESIGN

Case-control, prospective study.

SETTING

The University of California at San Francisco Obstetric and Gynecology Clinic.

PARTICIPANTS

Mothers screened for postpartum depression six weeks after delivery with the Edinburgh Postnatal Depression Scale and recruited as cases and controls.

MEASUREMENTS

Eligible subjects completed a series of assessments and a structured clinical interview to confirm diagnosis of depression. Deoxyribonucleic acid was obtained for genotyping of 81 single nucleotide polymorphisms in 12 genes hypothesized to be postpartum depression-related.

RESULTS

Twenty-four cases and 24 controls were eligible for analysis. Three single necleotide polymorphisms in the serotonin 2A receptor (HTR2A) gene were associated with postpartum depression. The strongest association at a functional promoter polymorphism (rs6311), a functional promoter single nucleotide polymorphisms (p=0.002, odds ratio 0.25, 95% confidence interval:0.10-0.63), was a finding robust to population stratification. Gene-wide association was significant for HTR2A (permuted p=0.008), but not when corrected for all 12 genes. Analysis of demographic and psychosocial risk factors identified distressed relationship, unplanned pregnancy, and a previous history of depression as significant predictive variables (p≤0.05).

CONCLUSIONS

This pilot data suggests deoxyribonucleic acid variations in HTR2A may be associated with postpartum depression. Psychosocial variables were also identified as risk factors. The relative influence of these variables on the manifestation of postpartum depression is yet to be determined.

Heart of Pharmacy: a course exploring the psychosocial issues of patient care

OBJECTIVE

To implement and assess the impact of a course utilizing reflective learning to explore the complex, psychosocial human issues encountered in pharmacy practice.

DESIGN

A 1-credit-hour elective course, The Heart of Pharmacy, was offered to all pharmacy students. The course utilized both content and reflective techniques to produce a mutual exploratory learning experience for students, staff, and faculty members. Faculty and staff facilitators observed competencies and used a single group posttest design to assess students' attitudes. In year four, students' written reflections for each session were added and reviewed on a continuous basis throughout the course.

ASSESSMENT

Faculty and staff observations indicated that educational outcomes were achieved and student perceptions and evaluations of the course were highly positive. Three major themes were identified in the students' qualitative responses: a recognition of communal support among student and faculty colleagues; a grounding for personal growth and professional formation; a deeper insight into and experience with the role of the pharmacist as compassionate listener and caregiver.

CONCLUSION

Faculty observations of student competencies and students' perceptions of this course point to the need for pharmacy education to provide organized, structured reflective learning opportunities for students and faculty members to explore the deeper human issues of pharmacy practice and patient care.

Tamoxifen treatment and new-onset depression in breast cancer patients

The authors conducted a retrospective cohort study of female patients diagnosed with breast cancer (BRCA), evaluating the risk of new-onset depression associated with tamoxifen treatment among those with estrogen receptor-positive (ER+) tumors, versus estrogen receptor-negative (ER-) tumors, who were not receiving tamoxifen. A total cohort of 2,943 patients was identified. The hazard-ratio for new-onset depression in the tamoxifen group was nonsignificant. A post-hoc analysis revealed that chemotherapy and ER+ status were significantly and independently associated with an increased risk for developing depression.

Evaluating the Impact of Pharmacists in Mental Health: A Systematic Review

Efforts to improve the outcomes of patients with mental illness often have involved incorporating the skills of a variety of health care professionals into collaborative care models. For over 30 years, clinical pharmacists have contributed to these care models in capacities ranging from educator to consultant to provider. This systematic review evaluates the quantity and quality of medical literature examining the impact of pharmacists in mental health from 1972-2003. Although we identified approximately 35 publications describing the roles of clinical pharmacists in this regard, only 16 were of sufficient scientific rigor to permit evaluation and comparison. The 16 studies were divided equally between inpatient and outpatient settings and were conducted in a variety of health care organizations (e.g., Veterans Administration, health maintenance organizations, community mental health clinics, and nursing homes). Nine of the studies examined the role of pharmacists in providing treatment recommendations and patient education, five featured pharmacists as providers (with prescriptive authority), and the remaining two described the impact pharmacists have in delivering education to the psychiatric staff. Six of the 16 studies were prospective, but only three of these incorporated a randomization procedure for patients or facilities. Collectively, the results of the 16 studies were positive, demonstrating improvements in outcomes, prescribing practices, patient satisfaction, and resource use. Unfortunately, most of the investigations were small, and significant limitations in study design limited further comparison. Given the long history and anecdotal success of pharmacists in mental health care settings, additional multicenter cost-effectiveness trials are warranted to further support the role of the psychiatric pharmacist.

Impact of a Collaborative Care Model on Depression in a Primary Care Setting: A Randomized Controlled Trial

To measure the effects of a collaborative care model that emphasized the role of clinical pharmacists in providing drug therapy management and treatment follow-up to patients with depression, we conducted a randomized controlled trial at a staff model health maintenance organization. We compared the outcomes of subjects treated in this collaborative care model (75 patients, intervention group) with subjects receiving usual care (50 patients, control group). After 6 months, the intervention group demonstrated a significantly higher drug adherence rate than that of the control group (67% vs 48%, odds ratio 2.17, 95% confidence interval 1.04-4.51, p=0.038). Patient satisfaction was significantly greater among members randomly assigned to pharmacists' services than among controls, and provider satisfaction surveys revealed high approval rates as well. Changes in resource utilization were favorable for the intervention group, but differences from the control group did not achieve statistical significance. Clinical improvement was noted in both groups, but the difference was not significant. Clinical pharmacists had a favorable effect on multiple aspects of patient care. Future studies of this model in other health care settings appear warranted.

Risk of seizures associated with psychotropic medications: emphasis on new drugs and new findings

Psychotropic medications in the classes of antidepressants, antipsychotics and mood stabilisers have been recognised in the literature and clinical settings as having high epileptogenic potential. Among these three classes, clozapine, tricyclic antidepressants (TCAs) and lithium are agents that clinicians have historically recognised as precipitants of drug-induced seizures. There are few reports that review the epileptogenic risk of newer psychotropic agents; in this qualitative review, the authors provide an update on the most recently published reports on seizures associated with antidepressants, antipsychotics, mood stabilisers, anxiolytics and sedative-hypnotics. In general, the epileptogenic risks of the newer psychotropic agents appear to be quite low as long as dosing strategies are consistent with recommended guidelines. Whilst newer psychotropic medications appear to be safe in patients with epilepsy, few studies have specifically addressed this population. In addition, the potential for drug interactions between antiepileptic drugs and psychotropics may be substantial with certain agents. For example, many psychotropes are both substrates and inhibitors of cytochrome P450 (CYP450) isoenzymes, whilst many antiepileptic drugs are both substrates and inducers of CYP450 activity. Every attempt should be made to minimise potential interactions when these agents are concomitantly administered.

Impact of a collaborative pharmacy practice model on the treatment of depression in primary care

The effects of a collaborative pharmacy practice model, in which clinical pharmacy specialists provided medication maintenance and follow-up patient care services at a clinic, on patients' adherence to treatment and satisfaction and costs were studied. A cohort of 13 primary care providers (PCPs) was designated to refer patients diagnosed with depression to the practice model at a staff-model health maintenance organization (HMO) immediately after the initiation of antidepressant medications. Clinical pharmacy specialists proceeded to coordinate follow-up with the patients for six months through a combination of scheduled office visits and telephone calls. Working closely with psychiatric liaisons, pharmacists were granted limited prescribing privileges to provide medication comanagement. These patients' adherence to treatment and satisfaction and costs to the HMO were compared with a control group of patients being treated for depression by the remaining 17 PCPs at the facility. A total of 91 patients were referred to the intervention group and received care from the pharmacists during the 10-month enrollment phase; 129 patients were included in the control group. There were no significant differences between groups regarding age, sex and chronic disease scores. An intent-to-treat analysis of medication adherence revealed that adherence was significantly higher in the intervention group (medication possession ratio, 0.81 versus 0.66) (p = 0.0005). Medication switch rates were higher among intervention patients as well (24% versus 5%) (p = 0.0001). There was a greater decline in the number of visits to PCPs for patients in the intervention group (39% versus 12%) (p = 0.029). A collaborative practice model in which clinical pharmacy specialists managed the medication therapy of patients with mild to moderate depression increased patients' adherence to treatment and their satisfaction and reduced the patients' subsequent visits to PCPs.

Clinical and economic outcomes associated with olanzapine for the treatment of psychotic symptoms in a county mental health population

BACKGROUND

The comparatively high acquisition costs of the newer antipsychotic medications have caused the mental health community to look closely at their potential benefits.

OBJECTIVE

The purpose of this study was to perform a naturalistic analysis of changes in mental health service utilization, economic costs, and clinical outcomes after the initiation of olanzapine therapy for psychotic symptoms in an indigent patient population from a large county-operated mental health care system.

METHODS

This was a prospective, uncontrolled investigation using a mirror-image cohort design. All captured costs from patients who began olanzapine therapy between November 1, 1996, and April 30, 1998, were analyzed in an intent-to-treat fashion to compare resource utilization in the 12 months immediately before and after the intervention. Clinical function was assessed at baseline and 6 months using the Positive and Negative Syndrome Scale (PANSS). In a subgroup analysis, the baseline characteristics of patients who completed 12 months of olanzapine treatment were compared with those of patients who (1) changed medication or (2) changed pay or source or were lost to follow-up.

RESULTS

One hundred eighty-nine patients were started on olanzapine treatment during the 18-month study entry phase. Patients were primarily male (63.5%) and had a mean age of 35.9 years. Most (66.3%) had a formal diagnosis of thought disorder. Fifty-six patients received olanzapine for 12 consecutive months, and 22 were switched to other psychotropic medications. Of the remaining 111 patients, 70 changed payors (ie, qualified for Medicaid), and 41 were lost to follow-up. In the subgroup analysis, patients who completed 12 months of treatment (ie, responders) had significantly lower mean PANSS total scores at baseline compared with those who changed payors or were lost to follow-up (P = 0.047), and were significantly more likely to have a formal diagnosis of thought disorder (P = 0.039). Responders demonstrated a significant reduction in PANSS total and negative subscale scores at 6-month follow-up (both measures, P < 0.001). In the intent-to-treat analysis of resource utilization in all patients with complete data sets (n = 78), hospitalization costs and crisis costs decreased significantly during the 12-month follow-up period (P = 0.003 and P = 0.009, respectively), and both outpatient and medication costs increased significantly (P = 0.035 and P < 0.001, respectively). Overall, the change in total annual resource utilization during the 12 months after initiation of olanzapine was not statistically significant (mean decrease per patient, $1,991; 95% CI, -$5,258 to $1,122).

CONCLUSIONS

Initiation of olanzapine therapy was associated with favorable clinical outcomes in this population, particularly in patients with a formal diagnosis of thought disorder. Overall, there was a cost shift away from hospital and crisis costs toward medication and outpatient services costs. The decline in total resource utilization was not statistically significant, although it may be of practical importance.

Risperidone: clinical outcome predictors and cost-effectiveness in a naturalistic setting

Although risperidone seems to be a safe and effective treatment for the management of psychotic symptoms, its acquisition cost is considerably higher than that of conventional antipsychotics, and its precise role in managing psychiatric illnesses has yet to be defined. The purpose of this investigation was to examine the relationship of patient demographic variables to therapeutic outcomes and to analyze the financial impact of risperidone on the treatment of psychotic symptoms. Subjects included in this 2-year, retrospective cohort, intent-to-treat analysis were all patients initiated on risperidone therapy at an inpatient psychiatric treatment facility. Clinical outcomes were assessed from the absolute change in hospitalized days, total number of psychotropic medications prescribed, and historic Clinical Global Impression severity scores. Logistic regression analysis was conducted to analyze the potential relationship to certain demographic variables to therapeutic response. The cost-benefit analysis compared the direct treatment costs incurred by the institution before and after risperidone initiation. Of the 66 patients originally started on risperidone, 57 completed a therapeutic trial. A clinical response was evident in 54 percent of these patients overall. Logistic regression analysis identified previous treatment intolerance and a negative history of substance abuse as predictive of therapeutic success with risperidone (p = .0006 and p = .01, respectively). Hospitalization rates declined by 43 percent among treatment responders and by 1.3 percent among nonresponders resulting in a net annual savings of $147,962. Risperidone may be efficacious in many patients who had previously failed antipsychotic trials. Patients who had been unable to tolerate traditional antipsychotics and those who lacked a documented history of substance abuse were uniquely responsive to risperidone treatment. The significant decline in hospitalized days that was observed among responsive patients seems to indicate that risperidone may be a cost-effective approach to the management of psychotic symptoms.

Lithium and angiotensin-converting enzyme inhibitors: evaluation of a potential interaction

The potential interaction between lithium and angiotensin-converting enzyme (ACE) inhibitors was investigated in a retrospective, longitudinal, case-control study of 20 hypertensive patients previously stabilized on lithium therapy. The objective of the study was to determine the impact of ACE inhibition on steady-state lithium concentrations and to evaluate the potential association of altered lithium clearance with age, renal function, and electrolyte balance. After initiation of the ACE inhibitor, steady-state lithium concentrations increased by 36.1%, lithium clearance was reduced by 25.5% (p < 0.0001), and four patients presented with symptoms suggestive of lithium toxicity. Significant bivariate correlations were observed for lithium clearance change and age (r = -0.45; p < 0.05) and for lithium clearance change and serum creatinine (r = -0.52; p < 0.02). Multiple regression analysis indicated that 25% of the change in lithium clearance was associated with a change in serum creatinine. This percentage was increased to 35% by the inclusion of age in the regression model. None of the other variables (age, height, weight, or change in serum sodium/potassium) made a significant contribution to this model. The authors concluded that a clinically important increase in lithium concentrations can occur in patients started on ACE inhibitor therapy. As elderly patients may be uniquely predisposed to this interaction, avoidance of this medication combination in older populations should be considered.

Clinical relevance of drug interactions with lithium

Although lithium continues to be regarded as the treatment of choice for bipolar disorders, the clinical use of this mood stabiliser is associated with an extremely narrow therapeutic range. Relatively minor increases in serum concentrations may induce serious adverse sequelae, and concentrations within the therapeutic range may result in toxic reactions. The safety of combining lithium with other medications, therefore, is a major concern, and extensive clinical experience has served to identify several significant drug interactions. Lithium removal from the body is achieved almost exclusively via renal means. As a result, any medication that alters glomerular filtration rates or affects electrolyte exchange in the nephron may influence the pharmacokinetic disposition of lithium. Concomitant use of diuretics has long been associated with the development of lithium toxicity, but the risk of significant interactions varies with the site of pharmacological action of the diuretic in the renal tubule. Thiazide diuretics have demonstrated the greatest potential to increase lithium concentrations, with a 25 to 40% increase in concentrations often evident after initiation of therapy. Osmotic diuretics and methyl xanthines appear to have the opposite effect on lithium clearance and have been advocated historically as antidotes for lithium toxicity. Loop diuretics and potassium-sparing agents have minor variable effects. Nonsteroidal anti-inflammatory drugs (NSAIDs) have also been associated with lithium toxicity, although the relative interactive potential of specific NSAIDs is difficult to determine. Small prospective studies have demonstrated large interindividual differences in lithium clearance values associated with different NSAIDs. A growing body of evidence also suggests that ACE inhibitors may impair lithium elimination, but further investigations are needed to identify patients at risk. Anecdotal reports have linked numerous medications with the development of neurotoxicity without an apparent effect on the pharmacokinetic disposition of lithium. Antipsychotics, anticonvulsants and calcium antagonists have all be implicated in a sufficient number of case reports to warrant concern. As these medications have all been commonly coadministered with lithium, the relative risk of serious interactions appears to be quite low, but caution is advised.

Measurement of prostaglandin E2 in rectal mucosa in human subjects: a method study

It has been demonstrated and confirmed that certain nonsteroidal anti-inflammatory drugs which inhibit cyclooxygenase and the synthesis of prostaglandins and other eicosanoids, can reduce the formation of both colon polyps and cancers in experimental animals given known carcinogens. Additionally, the results of several epidemiologic studies have suggested that nonsteroidal anti-inflammatory drugs may reduce the risk of colon polyp occurrence and/or colon cancer mortality. We have carried out a study to evaluate the methodology of the measurement of prostaglandin E2 (PGE2) in human colonic mucosa because its concentration may serve as a valuable intermediate marker of the pharmacological activity in Phase II studies of nonsteroidal anti-inflammatory drugs as colon cancer preventive agents. We studied all aspects of the actual measurement of PGE2 including the extraction efficiency of the PGE2 from the mucosa, the precision of the assay and calculation of the PGE2 content in terms of milligrams of protein in the sample, the inhibition of PGE2 by indomethacin over time, the reproducibility of the measurement within one homogenate, the rate of PGE2 production over time, the effect of adding indomethacin versus snap freezing on PGE2 production, the stability of PGE2 in tissues over time stored in liquid nitrogen, and the variability of the measurement of PGE2 in separate biopsies from one individual. Our studies indicated that the most reliable method for accurate and consistent measurements of PGE2 was to add the mucosal tissue instantly after biopsy to an indomethacin buffer that effectively inhibited the in vitro formation of PGE2.

Selective serotonin reuptake inhibitors: pharmacologic profiles and potential therapeutic distinctions

OBJECTIVE

To review the respective pharmacologic profiles of the selective serotonin reuptake inhibitors (SSRIs), with particular emphasis placed on clinically relevant distinctions.

DATA SOURCES

A MEDLINE search was conducted to identify English language literature published within the last five years on the four SSRIs (fluoxetine, sertraline, paroxetine, fluvoxamine). Previous review articles were scrutinized for additional citations, and manufacturers provided a contemporary bibliography of more recent material.

STUDY SELECTION/DATA EXTRACTION

Studies were selected for specific citation on the basis of comparative research merit and the contribution of this original literature to the pharmacologic profile(s) described.

DATA SYNTHESIS

All SSRIs appear to be more efficacious than placebo for the acute treatment of major depressive disorder (MDD). Short-term (six-week) efficacy was comparable with that of tricyclic antidepressants for the amelioration of MDD regarded as moderate in severity. Further comparative trials are clearly indicated to demonstrate the therapeutic benefits of SSRIs in specific populations (e.g., geriatric, severely ill) and to demonstrate sustained benefit with long-term prophylaxis. Other potential indications for SSRIs include obsessive-compulsive disorder, panic disorder, bulimia, and chronic pain syndromes. Pharmacokinetic profiles of the four SSRIs reveal similar parametric values, and most quantitative differences are of limited clinical significance. Adverse effects are common but ordinarily mild and transient, primarily restricted to the gastrointestinal tract and central nervous system. Important differences in the prevalence or severity of these adverse effects await the accumulation of further clinical experience and the completion of additional comparative trials. Similarly, the relative propensity of SSRIs to inhibit the metabolism of other medications is currently under investigation.

CONCLUSIONS

The four SSRIs studied appear to be more similar than they are different. Slowly, important distinctions are beginning to emerge with regard to adverse effect profiles and potential drug interactions. Given that the costs of these respective medications are comparable, such differences may ultimately serve to establish the preferential selection of individual agents in specific clinical situations.

Prospective study of the safety and financial benefit of ketoconazole as adjunctive therapy to cyclosporine after heart transplantation

In a prospective study of the relative safety and potential benefit of concomitant ketoconazole and cyclosporine after heart transplantation, 15 transplant recipients were followed up for up to 1 year (mean, 10.7 months) after ketoconazole was added to their immunosuppressive regimen of cyclosporine, prednisone, and azathioprine, and these patients were compared with a matched cohort over the same time. There was an 88% reduction in the mean (+/- SD) dose of cyclosporine, from 394 (115) mg/day to 47 (21) mg/day (p less than 0.0005) in the ketoconazole group, compared with an insignificant change in the control group. The projected annual cost of cyclosporine was reduced by 88%, with a 72% reduction in the projected cost of immunosuppressive drugs and prophylactic antifungal therapy, from a mean of $6800 to $1862 per year per transplant recipient in the ketoconazole-treated group. Other beneficial effects found over the study period included a significant reduction in the mean and diastolic systemic arterial pressure and a significant reduction in serum cholesterol. The mean total serum cholesterol fell from 265 (44) to 204 (38) mg/dl in the ketoconazole group but did not change significantly in the control group (p less than 0.005). Low-density lipoprotein cholesterol also fell from a mean of 167 (32) mg/dl to 112 (28) mg/dl (p less than 0.005). Renal function was not significantly affected by ketoconazole when compared with the control group. Ketoconazole and other drugs of potential use in organ transplant recipients should be evaluated for financial as well as for other potential clinical benefits in the long-term management of these patients.

Circulating levels of tumor necrosis factor and interleukin-1 in cystic fibrosis

To assess the role of tumor necrosis factor (TNF) and interleukin-1 (IL-1) in the pathophysiology of cystic fibrosis (CF)-associated growth failure/cachexia and lung disease we measured height, weight, triceps skin fold, forced vital capacity, forced expiratory volume in 1 second, and plasma levels of TNF, interleukin-1-alpha (IL-1 alpha), interleukin-1-beta (IL-1 beta), and alpha-1-antitrypsin (A1AT) in 12 patients with CF, and in 12 age- and gender-matched healthy controls. The patients as a group had significantly lower values for the anthropomorphic measurements and lung function parameters as compared to controls. They also had higher circulating levels of A1AT than controls. TNF, however, was detected less frequently in patients than in controls. Neither group had detectable levels of circulating IL-1 alpha or IL-1 beta, which is consistent with the observation that CF patients infrequently present with fever. Potential explanations for these findings include compartmentalization of secreted TNF/IL-1, altered regulation of TNF/IL-1 secretion as a result of the chronic inflammatory state seen in CF, or increased degradation of TNF/IL-1, also a result of chronic inflammation. The role of these cytokines in the pathophysiology of CF remains unclear, but should be explored further; however it seems unlikely that circulating TNF plays a role in the growth failure/cachexia associated with CF.

Regulation of tumor necrosis factor secretion in leukocytes from alpha-1-antitrypsin deficient humans

Alpha-1-antitrypsin (AT) is one of several alpha-globulins which have been shown to be inhibitors of human peripheral blood monocyte TNF secretion in vitro. AT deficiency states exist, within which individuals of either the PiSS or PiZZ phenotype have reduced hepatocyte and mononuclear phagocyte AT secretion when compared to normal PiMM subjects. Here we have compared the capacity of peripheral blood monocytes of all three phenotypes to respond to both enhancers and inhibitors of TNF secretion. All monocytes exposed to lipopolysaccharide (LPS), interferon-gamma (IFN-gamma) and endotoxin, PGE2, transforming growth factor-beta 1, whole plasma alpha-globulins, purified AT and IL-6 responded equally with respect to the secretion of TNF. Our findings show that the regulation of TNF secretion in leukocytes from AT deficient humans is normal and suggest that defective AT secretion alone does not result in the aberrant regulation of TNF secretion.

Effect of interleukin-2 on microvascular liquid and protein transport in the rat small intestine

Interleukin-2 (IL-2), a glycoprotein lymphokine derived from activated T-lymphocytes displays potent anti-cancer properties but its therapeutic use has been limited by generalized tissue swelling. To shed light on the mechanism underlying this potentially life-threatening edematogenic syndrome, recombinant IL-2 or an equal volume of control solution (excipient or 5% dextrose) was administered to 88 adult, male Sprague-Dawley rats. Initially, rats were injected with 50,000 Cetus units (equal to 300,000 I.U.) of IL-2 intraperitoneally, either one-time ("acute" rats) or every eight hours for two or seven days ("chronic" rats). Thereafter, under pentobarbital anesthesia, the main mesenteric lymph duct was isolated, incised, and measurements made of intestinal lymph flow (JV) and the total protein content and protein fractions in lymph (L) and plasma (P) (refractometry and agarose gel electrophoresis, respectively). Final measurements were also carried out after superior mesenteric vein constriction to assess filtration-independent L/P total protein "washdown." After IL-2, JV and protein clearance (JV x L/P) were increased (p less than 0.001) while lymph and plasma total protein content and protein fractionation were unchanged. Protein washdown was also maintained. These data are not only inconsistent with bulk "plasma leak" from damaged capillaries, but in conjunction with previously demonstrated increased cardiac output and reduced systemic vascular resistance after IL-2 administration, the findings favor augmented microvascular surface exchange area from increased capillary perfusion as the primary mechanism underlying increased transcapillary liquid and protein flux. This conclusion conforms to the rapid reversal of edema in patients after cessation of IL-2 therapy.

Comparison of ultrasonically applied vs. intra-articular injected hydrocortisone levels in canine knees

Phonophoresis of hydrocortisone is a commonly performed treatment for a wide variety of soft-tissue as well as intra-articular musculoskeletal disorders. There have been no previously reported studies indicating the degree of hydrocortisone penetration into joints achieved by means of phonophoresis. Twenty-four purebred greyhounds were used to compare intra-articular levels of hydrocortisone resulting from intra-articular injection, phonophoresis, and external application of hydrocortisone. A total of 40 samples from canine knees were analyzed by means of fluorescence polarization. Intra-articular hydrocortisone levels obtained with phonophoresis were extremely low in comparison with those obtained with intra-articular injection. There were no statistically significant differences in intra-articular hydrocortisone levels between the phonophoresis and external application treatments, or between either of these and placebo control measurements taken from knees of untreated dogs and from shoulders of treated dogs. It appears that phonophoresis is an ineffective method of obtaining hydrocortisone penetration into a joint in the canine model.

Plasma levels of fibronectin and prostacyclin metabolite in peripartum preeclamptic women

Plasma fibronectin and prostacyclin levels have been reported to vary in preeclamptic women when compared with pregnant control women. Elevation of fibronectin and deficiency of prostacyclin have been postulated to be due to endothelial cell disruption or dysfunction. Eighteen preeclamptic women and 19 normal pregnant controls were evaluated for plasma levels of fibronectin and the prostacyclin metabolite 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha). 6-keto-PGF1 alpha and fibronectin plasma levels in patients were significantly different from control patients, with preeclamptic patients exceeding control subjects. Five patients had serial samples of 6-keto-PGF1 alpha prior to, during, and after intravenous magnesium sulfate therapy and no consistent effect was noted. No correlation existed between fibronectin and 6-keto-PGF1 alpha levels or between either compound and platelet count or liver function tests. Despite an overall elevation of fibronectin in preeclamptic patients, two patients with the hemolysis, elevated liver tests, and low platelet count syndrome showed low normal fibronectin levels coinciding with thrombocytopenia, hemolysis, and liver dysfunction. The magnitude of fibronectin elevation may therefore not predict the severity of preeclampsia. The significance of these findings is discussed.

Immunochemical assays for IgG, IgA, IgM and transferrin compared

We compared immunochemical methods for determining IgG, IgA, IgM, and transferrin in serum by studying calibrator crossover, patient comparison, and, for a newly developed technology, normal reference intervals. For the immunoglobulins, we compared radial immunodiffusion (RID), rate nephelometry using the Beckman ICS, and a new nephelometric method adapted to the Abbott TDx; for transferrin we compared the ICS, TDx, and immunoturbiditry. The methods examined for quantifying IgA and transferrin showed good agreement in calibrator crossover and patient comparison studies. In studies comparing IgG methods, the ICS and TDx demonstrated acceptable agreement, although neither showed accordance with RID. For IgM determination, crossover studies and patients having less than 4300 mg/L in this protein showed good agreement, even though more elevated samples, run on the TDx, showed a discrepancy in proportionally compared to the other two methods. Normal reference intervals (95% confidence limits) determined on the TDx agreed well with those established for the other immunochemical methods.

Alpha-globulins suppress human leukocyte tumor necrosis factor secretion

The secretion of tumor necrosis factor (TNF) by human peripheral blood mononuclear cells was suppressed by either whole human plasma alpha-globulins or purified alpha 1-acid-glycoprotein, alpha 1-antitrypsin and alpha 2-macroglobulin in a concentration-dependent manner. alpha 1-Antitrypsin was found to be the most suppressive of the purified proteins tested and completely blocked TNF release at concentrations above 1.25 mg/ml. Both alpha 1-acid glycoprotein and alpha 1-antitrypsin blocked TNF secretion by leukocytes which were simultaneously stimulated with either recombinant human interferon-gamma (IFN-gamma) or lipopolysaccharide (LPS). IFN-gamma- and LPS-activated cells were also susceptible to suppression mediated by these two alpha-globulins and the inhibition produced by 5 mg/ml alpha 1-antitrypsin was greater than that caused by either 1 microM prostaglandin E2 or 10 ng/ml transforming growth factor-beta 1. The level of TNF mRNA in TNF-secreting and alpha-globulin-suppressed cells was examined and found to be equal in both groups. The suppressive effect of whole alpha-globulins was confined to the inhibition of TNF secretion and these plasma proteins had no effect on the cytolytic activity of the recombinant cytokine as measured on murine L-929 target cells. Thus the alpha-globulins, which are a major fraction of the circulating plasma proteins, may function in TNF homeostasis by controlling TNF secretion without inhibiting the biological activity of the released cytokine.

Precipitation of benzodiazepine withdrawal following sudden discontinuation of midazolam

Midazolam hydrochloride is an ultra-short acting benzodiazepine recently approved by the Food and Drug Administration for anesthesia induction and preoperative sedation. Frequently, midazolam is also used as an injection or infusion for the treatment of agitation in ventilator-dependent patients. A 53-year-old man underwent a gastrojejunostomy and was later intubated following the development of pseudomonal pneumonia. Midazolam was initiated in an effort to resolve his agitation and the patient continued to receive frequent bolus injections, averaging 22 mg/d over 21 days. Approximately eight hours after midazolam was abruptly discontinued, the patient became increasingly anxious and developed somatic complaints felt to be consistent with benzodiazepine withdrawal syndrome. Symptoms rapidly abated upon the reintroduction of midazolam and the drug was ultimately tapered over a period of four days and discontinued without further incident. Implications derived from the association of long-term midazolam therapy with benzodiazepine withdrawal syndrome are discussed.

Gonadotropin deficiency in Tourette's syndrome: a preliminary communication

Plasma baseline levels of gonadotropins and sex steroids were measured in 17 patients with Tourette's Syndrome (TS). In addition, a Gonadotropin Stimulation test, using a synthetic Gonadotropin releasing factor analogue (GnRH, 100 micrograms, i.v.), was performed in 7 patients. Plasma levels of Luteinizing Hormone (LH) were uniformly low in all patients, while those of Follicle Stimulating hormone (FSH) and sex steroids were less depressed in some patients and in the normal range in others. In all patients, stimulation with GnRH analogue produced a marked rise in LH levels, but the FSH responses were much less dramatic and did not significantly exceed that of normal controls. Our findings indicate reduced gonadotropin release in patients with TS, and support the hypothesis of hypothalamic involvement in the disease.

Raised serum levels of tumour necrosis factor in parasitic infections

In a study of serum levels of endogenous tumour necrosis factor (TNF) in healthy people and patients with neoplastic or infectious disease, only patients with kala-azar (visceral leishmaniasis) and malaria were found to have a strikingly increased frequency of raised TNF levels (66.6% and 70.0%, respectively). 7.9% of samples from both healthy subjects and patients with neoplastic disease contained measurable TNF. The discovery of elevated TNF levels in the sera of patients with parasitic diseases suggests that this cytokine may play a part in host defences against parasitic infections.

Amitriptyline plasma protein binding: effect of plasma pH and relevance to clinical overdose

Reversing ventricular ectopy with plasma alkalinization following acute tricyclic antidepressant overdose is a recognized mode of therapy. The mechanism responsible for this effect is unclear. Changes in plasma protein binding of free drug, effects of the sodium ion on the myocardium, and alterations of plasma concentrations of alpha-1-acid glycoprotein may all interact to alter toxicity of tricyclics in overdose. An in vitro investigation using equilibrium dialysis was designed to examine the effect of altering plasma pH on percentage of free amitriptyline at clinical overdose plasma concentrations. A 1973 report on this effect lacked adequate controls and was faulty in experimental protocol. The current investigation used plasma concentrations typically present in amitriptyline overdose, a sensitive gas liquid chromatographic assay to detect total and free drug, and adequate control of plasma pH. The results of two separate experiments demonstrated a significant decrease in percentage of free amitriptyline of 20% over a pH range of 7.0-7.4 (P less than 0.05) and 42% over a pH range of 7.4-7.8 (P less than 0.05). The rate of change in slope in both experiments was not significantly different (P less than 0.01) indicating similar effects of pH change on plasma protein binding of amitriptyline within the two groups.

Methotrexate: bioavailability and pharmacokinetics

Six adult patients with squamous cell carcinoma of the head and neck were treated with single low doses of methotrexate (MTX) (30 mg/m2) iv, im, and orally in the form of commercial tablets. A randomized crossover design was employed. Plasma concentrations were measured by a modified EMIT assay over a period of 24 hours following each dose. The mean (+/- SD) parameters following iv MTX were as follows: total-body clearance, 124 (36) ml/minute; Vss, 0.56 (0.18) L/kg; V lambda, 0.69 (0.24) L/kg; and beta-half-life, 3.20 hours. The absolute systemic bioavailability of the oral tablets was 36% (+/- 10%). After im administration, the systemic bioavailability was 93% (+/- 14%). Dose-dependent gastrointestinal absorption is suggested as the mechanism for the low availability of the oral tablets. Administration of MTX by the oral route will require further study to determine the optimal method of dosing.

Increased activities of MB and BB isozymes of creatine kinase in denervated neonatal and adult rat muscle

Creatine kinase (CK) activity and isozyme patterns were assessed in newborn and adult rat anterior tibial muscle in response to denervation. Total CK activity was low in the control neonatal muscle, gradually increasing to the adult level within 1 month. Denervation prevented this normal increase, and, therefore, CK activity was reduced to 25% of control at 2 months. In the denervated adult muscle, total CK activity decreased to 50% of control within 3 weeks and remained at that level. Denervation of neonatal muscle resulted in a greater conservation of MB isozyme compared with controls. The alteration in BB isozyme expression was even more dramatic with a 33-fold difference expressed at 2 months in terms of percent total CK in denervated vs. control muscle. In denervated adult muscle, MB and BB isozyme activities increased gradually, attaining levels 3-fold and 13-fold, respectively, above control muscle at the end of the experimental period.

Alterations in creatine kinase, ornithine decarboxylase, and transglutaminase during muscle regeneration

Creatine kinase (CK), transglutaminase (TGase) and ornithine decarboxylase (ODC), enzymes implicated in the regulation of growth processes, were studied during muscle regeneration subsequent to the injection of bupivacaine into rat tibialis anterior. Within 2 days, the percent BB isozyme of CK detected in the muscle was elevated 70-fold coincident with a marked decrease in total CK activity. The MB isozyme also increased and was 15-fold of control at 4-5 days postinjection. TGase activity was increased significantly to greater than 2-fold of control within 2 days of injection and significantly decreased at days 3 through 7 compared to controls. ODC activity was elevated significantly to 2- to 3-fold of control from 2-7 days after injection. These results suggest an early alteration in the expression of a coordinated battery of genes in this model of muscle degeneration-regeneration. The increased expression of MB and BB isozymes of CK in various human neuromuscular diseases may be a manifestation of an ongoing process of degeneration-regeneration.

Phagocytic, lambda light chain, plasma cell myeloma

A case of phagocytic, lambda light chain, plasma cell myeloma was characterized by its clinical, morphologic, cytochemical, immunologic, and cell kinetic features. A 40-year-old man presented with Coombs-negative hemolytic anemia, hepatosplenomegaly, lytic bone lesions, lambda light chain monoclonal gammopathy, and infiltration of the bone marrow by dysplastic plasma cells, 10% of which demonstrated phagocytosis of erythroid cells. Electron microscopy demonstrated myeloma cells with prominent cytoplasmic microfilaments and erythroid cells in intracytoplasmic vacuoles. The myeloma cells did not phagocytose staphylococci in vitro. Phagocytic and nonphagocytic myeloma cells were tartrate-sensitive, acid-phosphatase positive, alpha-napthyl butyrate esterase negative, and did not form E rosettes or EAox(IgG) rosettes. The tumor cells were Tdt, Ia antigen, and SIg negative. Immunofluorescent staining for cytoplasmic light chains showed a monoclonal lambda pattern in nonphagocytic myeloma cells, and a probable monoclonal lambda pattern in phagocytic myeloma cells. These findings characterize the neoplasm as a monoclonal proliferation of differentiated plasma cells with the capability of erythrophagocytosis. Erythrophagocytosis by myeloma cells may have been responsible for the hemolytic anemia. The tritiated thymidine labeling index (LI%) was high (8%), suggesting a poor prognosis, despite a dramatic initial response to chemotherapy.

Effect of alcohols and selected solvents on serum osmolality measurements

The method by which serum osmolality is measured can significantly affect the result if certain volatiles or solvents are present in the specimen. Commonly available solvents and alcohols were added to aliquots of pooled human serum to produce toxicologically relevant concentrations. Increasing concentrations of carbon tetrachloride, chloroform, mono-n-butyl ether (butyl cellosolve), 1, 1,1 trichloroethylene, toluene, and xylene did not change vapor pressure (VP) or freezing point depression (FPD) osmolality. Acetone, ethanol, isopropanol, and methanol in increasing concentrations produced a linear increase in FPD osmolality, but no change in VP osmolality. Only ethylene glycol produced a linear increase in VP and FPD osmolality across the range of concentrations studied. Despite the excellent correlation between osmolality and ethanol concentration in prepared serum samples, this relationship could not accurately predict patient ethanol concentrations from FPD osmolality. The osmolal gap, "delta" osmolality, (measured FPD minus calculated osmolality) did not correlate with the difference between measured FPD and VP osmolalities. Patient ethanol levels could not be predicted with accuracy using an equation based on the osmolal gap or "delta" osmolality.

Lidocaine elimination: effects of metoprolol and of propranolol

The effects of administration of metoprolol and propranolol on lidocaine elimination were studied in six healthy young men who did not smoke. Each received three single intravenous doses of lidocaine (2.5 to 3.0 mg/kg injected over 10 min): one alone, one after 1 day pretreatment with propranolol (40 mg orally every 6 hr), and one after 1 day pretreatment with metoprolol (50 mg orally every 6 hr). Lidocaine clearance was 0.88 +/- 0.28 l X hr-1 X kg-1 before beta blockade, 0.61 +/- 0.20 l X hr-1 X kg-1 during metoprolol dosing, and 0.47 +/- 0.16 l X hr-1 X kg-1 during propranolol dosing. There was no correlation between the change in lidocaine elimination and the steady-state concentrations of metoprolol or propranolol, nor between the change in lidocaine clearance and the change in resting heart rate produced by either beta blocker. Metoprolol and propranolol reduce lidocaine elimination significantly.

Assay of cerebrospinal fluid protein: a rate biuret method evaluated

We evaluated a rate colorimetric method (Beckman) for measuring total protein in cerebrospinal fluid. The automated instrument we used was Beckman's ASTRA TM. A 100-microL sample of spinal fluid is introduced into the biuret reagent in the reaction cell and the increase in absorbance at 545 nm is monitored for 20.5 s. Solid-state circuits determine the rate of alkaline biuret-protein chelate formation, which is directly proportional to the total protein concentration in the sample. The linear range of measurement is 120 to 7500 mg/L. Day-to-day precision (CV) over the range of 150 to 1200 mg/L ranged from 15.2 to 2.3%. The method was unaffected by radical alteration of the albumin/globulin ratio, but there is a positive interference in the presence of hemoglobin, a suppression in the presence of bilirubin, and no effect by xanthochromia. The method is precise, accurate, rapid, and convenient. The method was compared with the trichloroacetic acid method as performed on the Du Pont aca III, giving a correlation coefficient (r2) of 0.9693. The method is precise, accurate, rapid, and convenient.

Assay of cerebrospinal fluid protein: a rate biuret method evaluated

We evaluated a rate colorimetric method (Beckman) for measuring total protein in cerebrospinal fluid. The automated instrument we used was Beckman's ASTRA TM. A 100-microL sample of spinal fluid is introduced into the biuret reagent in the reaction cell and the increase in absorbance at 545 nm is monitored for 20.5 s. Solid-state circuits determine the rate of alkaline biuret-protein chelate formation, which is directly proportional to the total protein concentration in the sample. The linear range of measurement is 120 to 7500 mg/L. Day-to-day precision (CV) over the range of 150 to 1200 mg/L ranged from 15.2 to 2.3%. The method was unaffected by radical alteration of the albumin/globulin ratio, but there is a positive interference in the presence of hemoglobin, a suppression in the presence of bilirubin, and no effect by xanthochromia. The method is precise, accurate, rapid, and convenient. The method was compared with the trichloroacetic acid method as performed on the Du Pont aca III, giving a correlation coefficient (r2) of 0.9693. The method is precise, accurate, rapid, and convenient.

RBC zinc protoporphyrin to screen blood donors for iron deficiency anemia

We evaluated a rapid RBC zinc protoporphyrin (ZP) test in 1,147 male and 615 female blood donors to study its value in screening for evolving iron deficiency anemia. Fifteen men (1.8%) and 32 women (7.9%) who returned to donate were found to be anemic. A matched sample analysis between anemic and nonanemic donors demonstrated significant differences in serum ferritin levels, percent iron saturation, and the RBC ZP level from samples collected during the initial evaluation. Red cell ZP correlated well with the natural logarithm of serum ferritin in both men and women who later became anemic. The predictive value of RBC ZP levels compared favorably with that of the serum ferritin level. We also observed a strong association between the yearly donation frequency and RBC ZP concentration. These findings indicate that predonation RBC ZP testing may be useful in screening for iron depletion and potential risk of anemia in blood donors.