Benefit-risk profile of tofacitinib in patients with moderate-to-severe chronic plaque psoriasis: pooled analysis across six clinical trials.

BACKGROUND: Although existing psoriasis treatments are effective and well tolerated in many patients, there is still a need for new effective targeted treatment options. Tofacitinib is an oral Janus kinase inhibitor that has been investigated in patients with moderate-to-severe chronic plaque psoriasis. OBJECTIVES: To consider the benefits and risks of tofacitinib in patients with moderate-to-severe psoriasis. METHODS: Data were pooled from one phase II, four phase III and one long-term extension study comprising 5204 patient-years of tofacitinib treatment. Efficacy end points included patients achieving Physician's Global Assessments of 'clear' or 'almost clear', ≥ 75% and ≥ 90% reduction in Psoriasis Area and Severity Index (coprimary end points) and improvements in Dermatology Life Quality Index score, Hospital Anxiety and Depression Scale depression score and Itch Severity Item score, at weeks 16 and 52. Safety data were summarized for 3 years of tofacitinib exposure. RESULTS: Tofacitinib 5 and 10 mg twice daily (BID) showed superiority over placebo for all efficacy end points at week 16, with response maintained for 52 weeks of continued treatment. Tofacitinib improved patients' quality of life and was well tolerated. Rates of safety events of interest (except herpes zoster) were similar to those in the published literature and healthcare databases for other systemic psoriasis therapies. Tofacitinib 10 mg BID demonstrated greater efficacy than 5 mg BID. CONCLUSIONS: Tofacitinib has a benefit-risk profile in moderate-to-severe psoriasis consistent with that of other systemic treatments.

Association between serum interleukin-17A and clinical response to tofacitinib and etanercept in moderate to severe psoriasis.

BACKGROUND: Psoriasis is a systemic inflammatory disease with a pathophysiology involving interleukin (IL)-17. Tofacitinib is an oral Janus kinase inhibitor. Etanercept is a tumour necrosis factor-α inhibitor used in the treatment of psoriasis. Neither agent inhibits IL-17 directly. AIM: To evaluate correlations between circulating IL-17A and clinical efficacy in patients with psoriasis treated with tofacitinib or etanercept. METHODS: Serum concentrations of IL-17A homodimer and IL-17A/F heterodimer were determined by immunoassays at weeks 0, 4 and 12 in patients with moderate to severe psoriasis treated with placebo (n = 60), tofacitinib 5 mg twice daily (n = 184), tofacitinib 10 mg twice daily (n = 190), or etanercept 50 mg subcutaneously twice weekly (n = 190). Disease severity was assessed using the Psoriasis Area and Severity Index (PASI) and clinical response was defined as patients achieving ≥ 75% improvement from baseline PASI (PASI75). RESULTS: Serum levels of IL-17A homodimer at week 0 showed moderate correlation with PASI, with a Spearman correlation coefficient of 0.43. Furthermore, serum levels of IL-17A homodimer showed a clear correlation with clinical response, with a decrease of 57.1% in patients achieving PASI75 at week 12, but only 15.9% decrease in nonresponders. PASI75 responders had lower median concentrations of IL-17A (range across treatments: 0.24-0.27 pg/mL) at week 12 vs. nonresponders (0.37-0.62 pg/mL), regardless of the treatment. Serum IL-17A/F heterodimer showed similar decreases at week 12 in responders and nonresponders. CONCLUSIONS: Baseline serum IL-17A correlates moderately with psoriasis severity. Reduction in circulating IL-17A is required for disease remission regardless of therapeutic agent.

Tofacitinib withdrawal and retreatment in moderate-to-severe chronic plaque psoriasis: a randomized controlled trial.

BACKGROUND: Tofacitinib is an oral Janus kinase inhibitor being investigated for the treatment of moderate-to-severe plaque psoriasis. OBJECTIVES: To compare outcomes following tofacitinib withdrawal with outcomes of continuation. METHODS: In this phase 3 study (NCT01186744), patients received tofacitinib 5 mg (n = 331) or 10 mg (n = 335) twice daily for 24 weeks. The patients who achieved both ≥ 75% reduction in Psoriasis Area and Severity Index (PASI 75) score from baseline and Physician's Global Assessment (PGA) of 'clear' or 'almost clear' (PGA response) received a placebo (withdrawal) or the previous dose. At relapse (> 50% reduction in the PASI improvement during initial treatment) or week 40, the patients received the initial dose. RESULTS: Initial treatment: 33·5% and 55·2% achieved both PASI 75 and PGA responses with tofacitinib 5 and 10 mg twice daily, respectively, making them eligible for the treatment-withdrawal period. Withdrawal: 56·2%, 62·3%, 23·3% and 26·1% maintained PASI 75 responses with tofacitinib 5, 10 mg, placebo (5 mg) and placebo (10 mg) twice daily, respectively; 49·9%, 63·9%, 22·9% and 18·0% maintained PGA responses; and 92·3%, 93·0%, 32·8% and 42·9% did not relapse. Elevations in low-density lipoprotein-cholesterol levels following initial treatment (mean increase: 8·71 mg dL(-1) with 5 mg twice daily, 10·26 mg dL(-1) with 10 mg twice daily) were reversed upon withdrawal. Retreatment: 36·8% and 61·0% of patients who relapsed achieved PASI 75 responses with tofacitinib 5 or 10 mg after 16 weeks; 44·8% and 57·1% regained PGA responses. CONCLUSIONS: Patients who received continuous treatment maintained a response more effectively when compared with placebo recipients. Safety profiles were comparable in both the continuous treatment group and retreatment group. Of those patients who relapsed, up to 60% recaptured a response with tofacitinib.

Tofacitinib, an oral Janus kinase inhibitor, for the treatment of chronic plaque psoriasis: results from two randomized, placebo-controlled, phase III trials.

BACKGROUND: Tofacitinib is an oral Janus kinase inhibitor being investigated for psoriasis. OBJECTIVES: To determine the 16-week efficacy and safety of two oral tofacitinib doses vs. placebo in patients with moderate-to-severe chronic plaque psoriasis. METHODS: Patients in two similarly designed phase III studies (OPT Pivotal 1, NCT01276639, n = 901; OPT Pivotal 2, NCT01309737, n = 960) were initially randomized 2 : 2 : 1 to tofacitinib 10 or 5 mg or placebo, twice daily. Coprimary efficacy end points (week 16) included the proportion of patients achieving Physician's Global Assessment (PGA) of 'clear' or 'almost clear' (PGA response) and the proportion achieving ≥ 75% reduction in Psoriasis Area and Severity Index (PASI 75). RESULTS: Across OPT Pivotal 1 and OPT Pivotal 2, 745 patients received tofacitinib 5 mg, 741 received tofacitinib 10 mg and 373 received placebo. At week 16, a greater proportion of patients achieved PGA responses with tofacitinib 5 and 10 mg twice daily vs. placebo (OPT Pivotal 1, 41·9% and 59·2% vs. 9·0%; OPT Pivotal 2, 46·0% and 59·1% vs. 10·9%; all P < 0·001). Higher PASI 75 rates were observed with tofacitinib vs. placebo (OPT Pivotal 1, 39·9%, 59·2% and 6·2%, respectively, for tofacitinib 5 and 10 mg twice daily and placebo; OPT Pivotal 2, 46·0%, 59·6% and 11·4%; all P < 0·001 vs. placebo). Adverse event (AE) rates appeared generally similar across groups; rates of serious AEs, infections, malignancies and discontinuations due to AEs were low. Twelve patients reported herpes zoster across the tofacitinib treatment groups in both studies vs. none in the respective placebo groups. The most common AE across groups was nasopharyngitis. CONCLUSIONS: Oral tofacitinib demonstrated significant efficacy vs. placebo during the initial 16 weeks of treatment in patients with moderate-to-severe psoriasis. Safety findings were consistent with prior studies.

Effect of tofacitinib, a Janus kinase inhibitor, on haematological parameters during 12 weeks of psoriasis treatment.

BACKGROUND: The Janus kinase (JAK) inhibitor, tofacitinib, has shown efficacy for the treatment of psoriasis in a phase IIb trial (A3921047; NCT00678210). OBJECTIVES: To report haematology data from the phase IIb trial, given the importance of JAK-dependent signalling in haematopoiesis. METHODS: Patients with moderate-to-severe chronic plaque psoriasis were randomized to receive tofacitinib 2, 5 or 15 mg, or placebo, twice daily over 12 weeks. Blood samples were collected at screening, baseline, weeks 2, 4, 8 and 12 during treatment, and weeks 14 and 16 during off-treatment follow-up. RESULTS: Baseline haematology was similar across patients receiving tofacitinib 2 mg (n = 49), 5 mg (n = 49) or 15 mg (n = 49), or placebo (n = 50). Tofacitinib conferred dose-dependent decreases in haemoglobin, haematocrit and red blood cell counts, while reticulocyte counts initially declined, before recovering by week 8, and exceeding baseline levels after treatment cessation. With regard to white blood cells, tofacitinib had no clear dose-dependent effects on basophils or monocytes, but appeared to be associated with transient or reversible dose-dependent decreases in neutrophil and eosinophil counts and transient increases in lymphocyte counts, which were primarily attributable to increases in B-cell counts. Natural killer cell counts declined with tofacitinib. CONCLUSIONS: Tofacitinib conferred tolerable, dose-dependent changes in haematological parameters during short-term administration in patients with psoriasis. The effects did not appear to be progressive, and were often transient or reversible.

Efficacy and safety of tofacitinib, an oral Janus kinase inhibitor, in the treatment of psoriasis: a Phase 2b randomized placebo-controlled dose-ranging study.

BACKGROUND: Tofacitinib is a novel, oral Janus kinase inhibitor under investigation as a potential treatment for plaque psoriasis. OBJECTIVES: This Phase 2b, 12-week, dose-ranging study (A3921047, NCT00678210) aimed to characterize the exposure-response, efficacy and safety of tofacitinib vs. placebo in patients with moderate-to-severe chronic plaque psoriasis. METHODS: One hundred and ninety-seven patients were randomized. The primary endpoint was the proportion of patients achieving a ≥ 75% reduction in the Psoriasis Area and Severity Index (PASI 75) score at week 12. RESULTS: At week 12, PASI 75 response rates were significantly higher for all tofacitinib twice-daily groups: 25·0% (2 mg; P < 0·001), 40·8% (5 mg; P < 0·0001) and 66·7% (15 mg; P < 0·0001), compared with placebo (2·0%). Significant increases in the proportion of PASI 75 responses were seen by week 4 and were maintained at week 12. Exposure-response over the 0-15 mg tofacitinib twice-daily dose range was successfully characterized. PASI 50, PASI 90 and Physician's Global Assessment response rates were also higher for tofacitinib vs. placebo. The most frequently reported adverse events (AEs) were infections and infestations: 22·4% (2 mg twice daily), 20·4% (5 mg twice daily), 36·7% (15 mg twice daily) and 32·0% (placebo). Discontinuations due to AEs were 6·0%, 2·0%, 4·1% and 6·1% of patients in the placebo, and 2, 5 and 15 mg twice-daily tofacitinib groups, respectively. Dose-dependent increases from baseline in mean serum high-density lipoprotein, low-density lipoprotein and total cholesterol, and decreases in haemoglobin and neutrophils were observed. CONCLUSION: Short-term treatment with oral tofacitinib results in significant clinical improvement in patients with moderate-to-severe plaque psoriasis and is generally well tolerated.

Evaluating Dosage Optimality for Tofacitinib, an Oral Janus Kinase Inhibitor, in Plaque Psoriasis, and the Influence of Body Weight.

Tofacitinib is an oral Janus kinase inhibitor. An integrated analysis was conducted to evaluate dosage optimality for tofacitinib in patients with moderate-to-severe plaque psoriasis and the impact of body weight on optimality in this patient population. Data were pooled from one phase IIb trial (2, 5, and 15 mg twice daily (b.i.d.)) and four phase III trials (5 and 10 mg b.i.d.). A longitudinal exposure-response model for Psoriasis Area and Severity Index (PASI) improvement (percent change from baseline) was established. Body weight influenced potency; heavier subjects require higher doses to achieve comparable benefit to lighter subjects. Disease severity, sex, and prior biologic usage were also predictive of response. The 10 and 5 mg doses were predicted to achieve 81% and 65%, respectively, of the maximum effect based on a 75% improvement in PASI. The greater efficacy of 10 mg over 5 mg was clinically meaningful.

Quantitative Evaluations of Time-Course and Treatment Effects of Systemic Agents for Psoriasis: A Model-Based Meta-Analysis.

Aggregate data model-based meta-analysis is a regression approach to compare the dose-response and/or time-course across different treatments using summary level data from the literature. Literature search and systematic review following the Cochrane approach yielded 912 sources for investigational and approved treatments for psoriasis. In addition, data for tofacitinib were obtained from an internal database. Tofacitinib is an oral Janus kinase inhibitor. Two mathematical models were developed for Psoriasis Area and Severity Index (PASI) response in moderate to severe psoriasis patients to quantify the time to maximum effect for PASI75 and to evaluate the dose-response relationship for PASI responders (PASI50, PASI75, PASI90, PASI100) at Week 12. Body weight exhibited an inverse effect on the placebo component of both models, suggesting that body weight affects the overall PASI response regardless of drug. This analysis provides a quantitative framework for efficacy comparisons across psoriasis treatments.

Functional, structural, and dynamic basis of electrical heterogeneity in healthy and diseased cardiac muscle: implications for arrhythmogenesis and anti-arrhythmic drug therapy.

The electrophysiological properties of the ventricular myocardium are extremely heterogeneous. There are intrinsic electrical differences between the myocytes from different regions of the heart (most notably between the epicardium, midmyocardium, and endocardium), which are the result of different contributions of ionic currents to the transmembrane action potential. Sources of local anisotropy include directional differences in the distribution of gap junctions between adjacent myocytes and the presence of intercalated non-myocytes (e.g., fibroblasts), propagation boundaries, and wavefront collisions, which can lead to local variability of electrical load and, therefore, to nonuniform depolarisation and repolarisation. In addition, the complex anatomical arrangement of the myocardial fibres and nonuniform distribution of transmural mechanical stresses also contribute to electrical heterogeneity. Finally, dispersion of repolarisation is dynamically modified by the restitution properties of individual myocytes, stimulation rate, and the direction of conduction. All aspects of this electrical heterogeneity can be affected by different pathological conditions, such as myocardial ischaemia and cardiac hypertrophy. In particular, differential responses of various myocyte populations to these pathological stimuli and a marked increase in nonuniform anisotropy may be responsible for increased pro-arrhythmic potential in these conditions. In addition, the clinical effectiveness of anti-arrhythmic drugs may be related to their effects on electrical heterogeneity.

Regional electrophysiological effects of hypokalaemia, hypomagnesaemia and hyponatraemia in isolated rabbit hearts in normal and ischaemic conditions.

OBJECTIVE: The aims of this study were to establish an isolated working heart model for electrophysiological recordings from the epicardium and endocardium and to examine regional effects of changes in ion concentrations in normal and ischaemic conditions. METHODS: Monophasic action potential duration (MAPD90), effective refractory period (ERP) and conduction delay were measured simultaneously in the epicardium and endocardium of rabbit hearts paced at 3.3 Hz, subjected to 30 min of regional ischaemia and 15 min of reperfusion. The hearts were exposed before and throughout ischaemia and reperfusion to hypokalaemia (K+ = 2 mM), hypomagnesaemia (Mg2+ = 0.5 mM) or hyponatraemia (Na+ = 110 mM). RESULTS: In the control hearts, no regional electrophysiological differences were seen before ischaemia, but ischaemia-induced MAPD90 shortening and postrepolarisation refractoriness were greater in the epicardium than in the endocardium and conduction delay increased only in the epicardium. Hypokalaemia shortened ERP in the epicardium (but not endocardium) and increased conduction delay in all areas before ischaemia, but it had no effects during ischaemia. During reperfusion hypokalaemia increased the incidence of recurrent tachyarrhythmias. Hypomagnesaemia had no effect before ischaemia, increased epicardial (but not endocardial) MAPD90 shortening during ischaemia, although it had no pro-arrhythmic action. Hyponatraemia increased conduction delay in all areas before ischaemia and produced asystole or severe bradycardia in all hearts. During ischaemia, hyponatraemia decreased ERP shortening and inducibility of arrhythmias in the epicardium (but not endocardium). CONCLUSIONS: We conclude that the more pronounced effect of ischaemia upon the epicardium than the endocardium can be explained by the contact of the endocardium with intracavitary perfusate. We also conclude that changes in ion concentrations may have differential regional electrical effects in normal or ischaemic conditions.

Regional electrophysiological effects of left ventricular hypertrophy in isolated rabbit hearts under normal and ischaemic conditions.

OBJECTIVES: Left ventricular hypertrophy (LVH) has been reported to produce differential electrophysiological effects in isolated epicardial and endocardial cells. This study aimed to examine regional electrophysiological effects of LVH in normal and ischaemic conditions in the whole heart. METHODS: LVH was secondary to perinephritis-induced hypertension. Monophasic action potential duration (MAPD(90)), effective refractory period (ERP) and conduction delay were measured in paced, isolated working rabbit hearts either at one right ventricular and two left ventricular sites (apical and basal epicardium) or at three left ventricular sites (apical and basal epicardium, apical endocardium). The hearts were subjected to 30 min of regional ischaemia and 15 min of reperfusion. RESULTS: In non-ischaemic conditions, LVH produced uniform prolongation of MAPD(90) and ERP in the left ventricular epicardium, but not in the endocardium. After coronary artery occlusion, LVH significantly increased ischaemia-induced transepicardial dispersion of repolarisation, but not refractoriness. LVH did not affect arrhythmogenesis in either non-ischaemic or ischaemic conditions. CONCLUSIONS: Differential effects of LVH on epicardial and endocardial electrophysiological parameters are also observed in the whole heart. In addition, the sensitivity of hypertrophied myocardium to ischaemia is increased and leads to an increase in ischaemia-induced dispersion of repolarisation. However, neither dispersion of refractoriness nor arrhythmogenesis are affected by LVH in non-ischaemic or ischaemic conditions in this experimental model.

The course of life for old people.

Various aspects of institutional living for old people are discussed, particularly the imposition of a lifestyle completely foreign to their previous way of existence. Old people who have been living in one manner for about seventy years cannot be expected to adjust readily to another rhythm. The clash of lifestyles creates maladaptive behavior and adjustment problems that have not been adquately studied. Suggestions are made for approaches to resolve these difficulties. In essence, the techniques include reprogramming of institutional living for old people so that they have an opportunity to maintain their customary lifestyle. Examples of such programming are presented.

Immunology and adjuvant chemoimmunotherapy of breast cancer.

Antibody against a breast carcinoma antigen was present in patients with breast carcinoma and other cancer more often (P less than .05) than in normal women. The incidence of antibody in women with breast carcinoma correlated with the presence or absence of gross tumor, and the titer of antibody paralleled the clinical course. These results suggest importance of a host-immune response to breast carcinoma. Fifty-seven patients with stage II carcinoma of the breast were entered into a prospective randomized adjuvant chemoimmunotherapy program of cyclophosphamide, methotrexate, and fluorouracil, and BCG vaccine +/- an irradiated allogeneic tumor cell vaccine. After 24 months of study, metastases occurred in two patients (3.5%) and a new primary carcinoma developed in the contralateral breast in two others, for an overall treatment failure rate of 7%. Adjuvant chemoimmunotherapy can delay early recurrence. Long-term follow-up is needed to assess the significance of these results.

Facilitation of spontaneous defibrillation by moxonidine during regional ischaemia in an isolated working rabbit heart model.

Moxonidine has been shown to be antiarrhythmic during ischaemia in vivo. This study aimed to investigate its electrophysiological effects in isolated working rabbit hearts in vitro. Monophasic action potential duration, effective refractory period and conduction delay were measured at three ventricular sites. The hearts were treated before and during ischaemia and reperfusion with vehicle, moxonidine (0.01, 0.1 and 1 microM) or labetalol (1 microM). In all groups, ventricular fibrillation was always induced during ischaemia. Only 0.1 microM moxonidine decreased the incidence of sustained ventricular fibrillation from 86 to 17%, although it did not affect any electrophysiological parameters measured. Similarly, labetolol, an adrenoceptor blocker, facilitated spontaneous defibrillation without any electrophysiological effects. In conclusion, moxonidine directly facilitates spontaneous defibrillation of ventricular fibrillation during ischaemia. Since the same effect is observed with labetalol, it is possible that the defibrillatory action of moxonidine is related to its peripheral antiadrenergic activity, although other mechanisms cannot be excluded.

Nifedipine and captopril exert divergent effects on heart rate variability in patients with acute episodes of hypertension.

Acute changes of heart rate variability (HRV) depict alterations in autonomic influences on cardiovascular system and often precede ventricular arrhythmias. The aim of the study was to assess effects of sublingual 10 mg nifedipine (n = 15) or 25 mg captopril (n = 13) on HRV in consecutive patients admitted to hospital due to severe hypertension. HRV was calculated on-line from 300 cardiac cycles before and 60-90 min after drug administration. At baseline systolic blood pressure (SBP) was > 190 mm Hg and/or diastolic blood pressure (DBP) > 110 mm Hg. Both agents caused similar reduction of blood pressure (BP). Nifedipine reduced variance (-63 +/- 6%; P < 0.0001) and high-frequency (HF) component (-72 +/- 8%; P < 0.0001), and increased both LF/HF ratio (+870 +/- 336%; P < 0.02) and heart rate (+14 +/- 3%; P < 0.0001). Captopril exerted different effects: variance and HF component increased by +176 +/- 55%; (P < 0.007) and +126 +/- 44% (P < 0.015), respectively. LF/HF (low/high frequency) ratio decreased (-44 +/- 19%; P < 0.04) together with heart rate (-4 +/- 1%; < 0.009). It is concluded that captopril, in contrast to nifedipine, increases HRV and decreases LF/HF ratio and therefore is a better choice in hypertensive patients who might be prone to dangerous arrhythmias.

Parenteral nutrition in obstetrics and gynecology.

Parenteral nutrition is required to maintain and restore an anabolic state when oral or enteral routes are not feasible. Despite 16 years of parenteral nutrition availability, reports about parenteral therapy in gynecologic patients or during pregnancy have not been published until relatively recently. Most information is anecdotal but suggests that this mode of therapy is safe, effective, and occasionally life-saving. Parenteral nutrition is used most commonly in women with gynecologic malignancies who are unable to obtain adequate nourishment either during or after surgery, radiation, or chemotherapy. Parenteral alimentation during pregnancy has been used mostly to provide adequate nutrition for those who suffer from prolonged hyperemesis or when there is difficulty in absorption of adequate nutrients. The proper selection and administration of dextrose, fat, protein, vitamins, trace elements, and electrolytes for pregnant women has been associated with apparent favorable perinatal outcomes. Preterm deliveries and intrauterine fetal growth retardation are relatively common and relate to the preexisting or a coexisting medical or obstetric complication. Nutritional assessment before therapy should include a detailed diet history and establishment of baseline clinical and laboratory parameters. Oral or enteral feedings should be attempted beforehand if possible to conserve high costs and potential complications. Parenteral requirements are extrapolated from recommended daily allowances for oral intake, allowing for adjustments in variable absorption. Standardized formulations and fat emulsions are available at pharmacies in many hospitals, making ordering of complex solutions easier, more efficient, and cost effective. Metabolic and septic complications occur infrequently with close monitoring. Few women require intravenous therapy for very long, and home parenteral nutrition is rarely necessary.

The incidence of asymptomatic paroxysmal atrial fibrillation in patients treated with propranolol or propafenone.

Anti-arrhythmic therapy for paroxysmal atrial fibrillation leads to complete symptomatic relief in a number of patients. The elimination of symptoms may be associated either with a complete elimination of arrhythmia or with a conversion of symptomatic atrial fibrillation into asymptomatic episodes of arrhythmia. The aim of the study was to evaluate the occurrence of asymptomatic paroxysmal atrial fibrillation in 52 patients treated with propafenone (35 drug trials) or propranolol (34 drug trials) by means of ambulatory ECG Holter monitoring. Propafenone was clinically effective (complete relief of symptoms) in 26 (74%) patients. However, in 7 cases (27%) asymptomatic episodes of arrhythmia were still recorded when awake. In patients treated with propranolol clinical symptoms were absent in 18 (53%). However, in 4 (22%) patients attacks of paroxysmal atrial fibrillation were present. The mechanism of drug-induced conversion of symptomatic episodes of atrial fibrillation into asymptomatic spells of arrhythmia was a marked shortening in duration of episodes in 7 patients (from 2215 +/- 3843 s to 16 +/- 10 s, N.S.) or by a significant slowing of ventricular response during atrial fibrillation in 4 patients (from 125 +/- 27 to 84 +/- 8 beats/min, P = 0.05). In conclusion, in a significant proportion of patients with symptomatic paroxysmal atrial fibrillation asymptomatic episodes of arrhythmia may occur while on anti-arrhythmic drug therapy. Some of these patients, particularly those with other risk factors for stroke such as advanced age or the presence of organic heart disease, may require anti-coagulant therapy or change in anti-arrhythmic treatment, and can be selected on the basis of ambulatory ECG monitoring.

Effects of oral L-arginine supplementation on exercise-induced QT dispersion and exercise tolerance in stable angina pectoris.

We assessed the effects of L-arginine (an endogenous precursor of nitric oxide) on the magnitude of exercise-induced QT dispersion in patients with coronary artery disease. The study had a randomized double-blind cross-over design. Twenty-five patients with stable coronary artery disease underwent two separate exercise tests: after oral administration of L-arginine (6 g/24 h for 3 days) or placebo. Indications for cessation of exercise included: pulse limit, exhaustion, chest pain, ST segment depression >2 mm. We found that arginine significantly increased exercise duration from 604+/-146 to 647+/-159 s (P<0.03). However, it had no effect on the sum of exercise-induced ST segment depressions (1.9+/-2.3 and 2.4+/-3.3 on and off arginine, respectively, NS). Exercise shortened QT interval to a similar extent in patients treated with placebo or arginine. QT dispersion changed during exercise from 55+/-21 to 60+/-19 ms (NS) and from 60+/-21 to 53+/-17 ms (NS), respectively. We conclude that, in patients with coronary artery disease, oral supplementation of L-arginine does not affect exercise-induced changes in QT interval duration, QT dispersion or the magnitude of ST segment depression. However, it significantly increases exercise tolerance, most likely due to improved peripheral vasomotion. These results may be of clinical and therapeutic importance.

Stability of imipenem and cilastatin sodium in total parenteral nutrient solution.

The chemical stability and compatibility of imipenem-cilastatin sodium (Primaxin) in two different total parenteral nutrient (TPN) solutions was determined. TPN solutions consisted of 4.25% and 5% amino acids with 25% and 35% dextrose, respectively. Imipenem-cilastatin sodium was constituted with 10 ml of sterile water and admixed with 90 ml of TPN solution for a final concentration of 5 mg/ml of each drug. The final solutions were assayed at times 0 (immediately after admixture), 15 min, 30 min, 1, 4, 8, and 24 hr by a stability-indicating high-performance liquid chromatographic assay. Concurrently, test TPN solutions were monitored for pH changes, color changes, and precipitate formation. The potential effect of imipenem-cilastatin sodium on the stability of amino acids and other TPN additives was not evaluated. Imipenem and cilastatin sodium was stable (greater than or equal to 90% recovered) in each TPN solution at 15 min. A significant (greater than or equal to 10%) and steady decrease of imipenem recovery occurred at subsequent sampling times. Cilastatin appeared more stable than imipenem in both TPN solutions. A physical color change from colorless to dark orange appeared in each TPN solution over the 24-hr study period. Imipenem-cilastatin sodium is stable for 15 min in the TPN solutions studied; however, until the stability of the amino acids can be determined, the antibiotic should be administered through a separate line or Y-site while the TPN infusion is interrupted.

Role of the endogenous nitric oxide in the vasodilatory tone and CO2 responsiveness of the rostral ventrolateral medulla microcirculation in the rat.

The study was designed to check the role of endogenous NO in maintaining the vasodilatory tone and in mediation of local cerebral blood flow (CBF) responses to CO2 in rostral ventrolateral medulla (RVLM) in the rat. The ventral surface of the medulla was exposed and CBF in the RVLM continuously recorded with a laser-Doppler flowmeter. Local vascular resistance (CVR) was estimated as the ratio of mean arterial pressure (MAP) to CBF. During 1 min exposure to 10% CO2 in oxygen PaCO2 rose from 39.9 +/- 2 mm Hg to 89.7 +/- 4.6 mm Hg and pH fell from 7.4 +/- 0.04 to 7.1 +/- 0.03. After intravenous administration of 15 mg/kg L-NAME (Nitro-L-arginine-methyl ester) MAP increased by 43 +/- 2.9 mm Hg (p < 0.001), local CBF increased by 33 +/- 6% (p < 0.001) and CVR increased by 17 +/- 6% (p < 0.01). L-NAME significantly reduced CBF flow response to 60 s hypercapnia from 47 +/- 9% (p < 0.001) before administration of L-NAME to 14 +/- 5% (p < 0.001). This effect was due to reversal by L-NAME of a pressor response to hypercapnia to a depressor response. The attenuation of CVR response to CO2 by L-NAME was too small to account alone for the significant reduction of local CBF responsiveness to hypercapnia. We conclude that endogenous NO plays a role in maintaining a local vasodilatory tone in RVLM, but it is less significant than in the cortical microcirculation. NO is not a major mediator in the increase in local CBF in RVLM during brief hypercapnia. Endogenous NO is critical for the neurogenic pressor response to brief hypercapnia.