Nitroglycerin lingual spray: clinical efficacy and dose-response relation

Associations between nutritional factors and excessive daytime sleepiness in older patients with chronic kidney disease

BACKGROUND

Excessive daytime sleepiness (EDS) is prevalent in not only older adults, but also patients with chronic kidney disease (CKD), and is associated with higher risks of morbidity and mortality.

AIMS

The aim of the present study is to determine associations between EDS and nutritional status and serum nutrient levels in older patients with CKD.

METHODS

This cross-sectional study included 367 patients (aged ≥ 65 years) with CKD (eGFR < 60 ml/min/1.73 m² and/or > 30 mg/day of albuminuria for > 3 months). EDS was recorded using the Epworth Sleepiness Scale (a score of ≥ 11). Malnutrition was diagnosed according to the Mini Nutritional Assessment (MNA) tool (a score of < 17).

RESULTS

The mean age was 81 ± 7 years, and 248 (67%) were female. EDS was seen in 99 (26.9%) patients. Those with EDS had significantly lower MNA scores and more frequent malnutrition than those without EDS (p < 0.05). In multivariable analysis adjusted for age, sex, cerebrovascular disease, dementia, number of drugs, and number of urinations at night, and the Charlson Comorbidity Index the relationship between malnutrition and EDS persisted (OR 2.58, 95% CI 1.38-4.83, p = 0.003). There was no significant difference between the presence of EDS and serum levels or deficiencies of vitamin D, vitamin B₁₂, and folate (p > 0.05).

CONCLUSIONS

EDS is associated with malnutrition in older patients with CKD. Therefore, EDS and nutritional status should be evaluated together in clinical practice. However, future studies are needed to determine the direction of the association between malnutrition and EDS and to evaluate if dietary intervention can improve EDS.

Pilot randomized sham-controlled trial of self-acupressure to manage the symptom cluster of insomnia, depression, and anxiety in cancer patients undergoing chemotherapy

PURPOSE

Current evidence for using self-acupressure to manage the cancer-related symptom cluster of insomnia, depression, and anxiety, while promising, is unknown. This study evaluated the feasibility of self-acupressure to manage this symptom cluster and to explore its potential effectiveness.

METHODS

Participants were assigned randomly to three study groups, namely the true acupressure (TAP), the sham acupressure (SAP), and the enhanced standard care group (ESC). Participants in the TAP and SAP groups received a training session on acupressure and were required to practice self-acupressure at home once per day for 28 days. The duration of participant involvement was 8 weeks. Patients completed a Numerical Rating Scale (NRS) for each symptom, the Insomnia Severity Index, the Hospital Anxiety and Depression Scale, and the Functional Assessment of Cancer Therapy-General at baseline (T1), post-intervention (T2, week 4), and post follow-up (T3, week 8).

RESULTS

The results indicated that the intervention had clinical significance in improving the targeted symptoms and quality of life. In the TAP group, the symptom cluster severity was significantly lower than in the other groups at T2 (p < 0.05). The insomnia severity and anxiety scores in the TAP and SAP groups were significantly lower than those in ESC at T2 and T3 (p < 0.05).

CONCLUSION

The trial was feasible. The promising results of the study suggest that further testing of self-acupressure is warranted to inform its effectiveness on the targeted symptom cluster in patients with cancer. A placebo effect was evident alongside therapeutic effects.

TRIAL REGISTRATION

ClinicalTrials.gov (ID: NCT03823456) on January 30th, 2019.

Subgrouping Poor Sleep Quality in Community-Dwelling Older Adults with Latent Class Analysis - The Yilan Study, Taiwan

The manifestation of older adults with poor sleep quality is heterogeneous. Using data-driven classifying methods, the study aims to subgroup community-dwelling older adults with poor sleep quality. Adults aged 65 and older participated in the Yilan study. Poor sleep quality was defined using the Pittsburgh Sleep Quality Index. Latent class analysis with the 7 subscores of the Pittsburgh Sleep Quality Index as the indicators was used to generate empirical subgroups. Differences in comorbidity patterns between subgroups were compared. A total of 2622 individuals, of which 1011 (38.6%) had Pittsburgh Sleep Quality Index -defined poor sleep quality, participated. Three groups for poor sleep quality were specified in the latent class analysis: High Insomnia (n = 191, 7.3%), Mild Insomnia (n = 574, 21.9%), and High Hypnotics (n = 246, 9.4%). The High Insomnia and Mild Insomnia groups shared similar profiles but different severities in the 7 domains of the Pittsburgh Sleep Quality Index. In contrast, the High Hypnotics group had the lowest Pittsburgh Sleep Quality Index total scores and insomnia severity but had similar mental and physical comorbid patterns as the High Insomnia group. This finding suggests that poor sleep quality in community-dwelling older adults had various feature-based subgroups. It also implicates the development of group-centered interventions.

Stable angina pectoris: the medical management of symptomatic myocardial ischemia

Coronary artery disease (CAD) remains an important cause of morbidity and mortality and is a serious public health problem. Over the last 4 decades there have been dramatic advances in the both the prevention and treatment of CAD. The management of CAD was revolutionized by the development of effective surgical and percutaneous revascularization techniques. In this review we discuss the importance of the medical management of symptomatic, stable angina. Medical management approaches to both the treatment and prevention of symptomatic myocardial ischemia are summarized. In Canada, organic nitrates, β-adrenergic blocking agents, and calcium channel antagonists have been available for the therapy of angina for more than 25 years. All 3 classes are of proven benefit in the improvement of symptoms and exercise capacity in patients with stable angina. Although there is no clear first choice within these classes of anti-anginal agents, the presence of prior or concurrent conditions (for example, prior myocardial infarction and/or hypertension) plays an important role in the choice of anti-anginal class in individual patients. For some patients, combinations of different anti-anginal agents can be effective; however it is recommended that this approach be individualized. Although not currently available in Canada, other classes of anti-anginal agents have been developed; their mechanism of action and clinical efficacy is discussed. Patients with stable angina have an excellent prognosis. Patients in this category who obtain relief from symptomatic myocardial ischemia may do well without invasive intervention.

Nitrates as an integral part of optimal medical therapy and cardiac rehabilitation for stable angina: review of current concepts and therapeutics

The goals of optimal medical therapy in patients with stable angina pectoris are to reduce the risk of cardiovascular mortality and future cardiovascular events, improve exercise capacity, and enhance quality of life. Whereas myocardial revascularization is frequently employed in the management of patients with stable angina, a variety of pharmacologic interventions are recommended as part of optimal medical management. The use of short- and rapidly-acting nitrates (eg, sublingual nitroglycerin spray and tablets) is at the core of the therapeutic armamentarium and should be integrated into optimal medical therapy for stable angina along with exercise therapy. The potential clinical implications from these observations are that prophylactic sublingual nitrates, when combined with cardiac rehabilitation, may allow the patient with angina to exercise to a greater functional capacity than without sublingual nitrates.

A randomized, double-blind, placebo-controlled, crossover, dose-ranging multicenter study to determine the effect of sublingual nitroglycerin spray on exercise capacity in patients with chronic stable angina

BACKGROUND

Sublingual nitroglycerin increases exercise duration in patients with stable angina. Brief results from this study were published previously in German. Here, we more fully describe the study methodology, patient characteristics, and detailed results.

METHODS

This double-blind, crossover study enrolled 51 patients with stable angina. Patients were randomized to 1 of 5 treatment sequences and were administered placebo or nitroglycerin spray (0.2 mg, 0.4 mg, 0.8 mg, or 1.6 mg). Patients carried out 1 control exercise tolerance test (ETT) and 1 investigational ETT at each visit.

RESULTS

Dose-dependent increases in time to onset of angina, time to onset of moderate angina, and the occurrence of a minimum 1.0-mm ST-segment depression were seen following administration of nitroglycerin spray.

CONCLUSIONS

These results support the use of sublingual nitroglycerin spray in patients with stable angina who are being managed with medical therapy and in patients who have persistent angina post-revascularization.

Permeation of quinine across sublingual mucosa, in vitro

Quinine is the first line treatment in severe P. falciparum malaria and nocturnal leg cramps and a fast, convenient delivery method of this drug quinine is needed. The purpose of this study was to investigate in vitro the sublingual route for the delivery of quinine. Permeation studies were carried out with Franz diffusion cells containing sublingual mucosa membranes with PBS receptor phase and dosed with solutions of quinine hydrochloride or quinine/2-hydroxypropyl-beta-cyclodextrin complexes. Receptor phase samples were taken 2 hourly over a 12h period and quinine was determined by reverse-phase HPLC analysis. The ventral surface of the tongue was significantly more permeable than porcine floor of the mouth (p<0.05) and there was no significant effect of freezing on the ventral surface of the tongue (p 0.2444). The presence of saliva caused a decrease in the permeation of quinine across the ventral surface of the tongue by up to 68%. Inclusion complexation between quinine and 2-HP-beta-CD was supported by (1)H NMR spectral data, and an ethanol vehicle provided the highest quinine flux from the inclusion complex solutions compared to deionised water and PEG. Overall, the data support further investigations into the clinical use of sublingual quinine, particularly for children with falciparum malaria or patients with nocturnal leg cramps. Use of quinine/cyclodextrin inclusion complexes may circumvent compliance issues due to bitter taste.

Chronic angina pectoris: inadequacies of current therapy

Chronic angina is a major medical problem in the United States with more than 6 million patients affected, a number that will increase substantially because of the progressive aging of the population. The annual mortality rate for patients with chronic angina is approximately 2%, but is much higher in certain subsets of patients, particularly the elderly. Angina is also associated with major social and economic burdens. Because of poor symptom control and hemodynamic, as well as other drug side effects, angina is commonly associated with a poor quality of life. No new class of drug has been available for angina treatment in more than two decades, and current medications frequently fail to provide adequate symptom control. Thus, the majority of patients are taking two or three antianginal medications. New agents that modulate myocardial metabolism have shown antianginal efficacy, a favorable side-effect profile, and an absence of hemodynamic effects.

Preserved flow-mediated dilation in the inactive legs of spinal cord-injured individuals

The aim of the study was to assess endothelial function, measured by flow-mediated dilation (FMD), in an inactive extremity (leg) and chronically active extremity (arm) within one subject. Eleven male spinal cord-injured (SCI) individuals and eleven male controls (C) were included. Echo Doppler measurements were performed to measure FMD responses after 10 and 5 min of arterial occlusion of the leg (superficial femoral artery, SFA) and the arm (brachial artery, BA), respectively. A nitroglycerine spray was administered to determine the endothelium independent vasodilatation in the SFA. In the SFA, relative changes in FMD were significantly enhanced in SCI compared with C (SCI: 14.1 +/- 1.3%; C: 9.2 +/- 2.3%), whereas no differences were found in the BA (SCI: 12.5 +/- 2.9%; C: 14.2 +/- 3.3%). Because the FMD response is directly proportional to the magnitude of the stimulus, the FMD response was also expressed relative to the shear rate. No differences between the groups were found for the FMD-to-shear rate ratio in the SFA (SCI:0.061 +/- 0.023%/s(-1); C: 0.049 +/- 0.024%/s(-1)), whereas the FMD-to-shear rate ratio was significantly decreased in the BA of SCI individuals (SCI: 0.037 +/- 0.01%/s(-1); C: 0.061 +/- 0.027%/s(-1)). The relative dilatory response to nitroglycerine did not differ between the groups. (SCI: 15.6 +/- 2.0%; C: 13.4 +/- 2.3%). In conclusion, our results indicate that SCI individuals have a preserved endothelial function in the inactive legs and possibly an attenuated endothelial function in the active arms compared with controls.

Smooth muscle dysfunction occurs independently of impaired endothelium-dependent dilation in adults at risk of atherosclerosis

OBJECTIVES

We sought to assess smooth muscle function in adults at risk for atherosclerosis.

BACKGROUND

Previous studies in subjects at risk for atherosclerosis have demonstrated arterial endothelial dysfunction, with reduced vasodilator responses after pharmacologic or physiologic stimulation of endothelial nitric oxide (NO). Most have also shown a slight but nonsignificant impairment of vasodilation in response to exogenous sources of NO, such as nitroglycerin (NTG). We hypothesized that NTG responses might be reduced in a large number of consecutively studied adults at risk for atherosclerosis, independent of any impaired endothelium-dependent responses, consistent with concomitant smooth muscle dysfunction.

METHODS

Using high resolution ultrasound, the dilator response of the brachial artery to 400 microg of sublingual NTG was measured in 800 asymptomatic subjects. Subjects were also assessed for a history of vascular risk factors, blood pressure, total serum cholesterol and flow-mediated endothelium-dependent dilation (EDD).

RESULTS

We studied 317 men and 483 women, 38 +/- 17 years old (mean +/- SD, range 15 to 76). The mean cholesterol level was 5.2 +/- 1.3 mmol/liter, and there were 126 smokers and ex-smokers (16 +/- 9 mean pack-years) and 105 diabetic subjects. On univariate analysis, a reduced vasodilator response to NTG was associated with high cholesterol, cigarette smoking, diabetes mellitus, increasing age, male gender, larger vessel size and reduced EDD (p < or = 0.01 for all). On multivariate analysis, diabetes, larger vessel size and reduced EDD were all independently associated with impaired NTG-related vasodilation (p < or = 0.001 for all). In the 574 nondiabetic subjects who had never smoked cigarettes, the independent relation between EDD and NTG responses was still observed (r = 0.24, p = 0.01).

CONCLUSIONS

The vasodilator response to exogenous NO is impaired in asymptomatic subjects with reduced EDD, consistent with smooth muscle dysfunction in adults at risk for atherosclerosis.

Effect of wetting the mouth on aortic blood pressure just before taking sublingual nitrates

The absorption of sublingual nitrate tablets is sometimes variable. We performed a randomized controlled trial to determine whether wetting the mouth improved the decrease in aortic systolic blood pressure (BP) from sublingual nitrate tablet or spray. The 100 patients undergoing routine diagnostic cardiac catheterization were allocated to control (no nitrate), 0.3 mg sublingual nitrate tablet, 0.4 mg sublingual nitrate spray, water + 0.3 mg sublingual nitrate tablet, or water + 0.4 mg sublingual nitrate spray. Aortic systolic and diastolic BP were recorded using a fluid-filled catheter and measured off-line blind to the treatment group. Compared with control subjects, there were significant decreases in aortic systolic BP with both nitrate preparations (tablet = -7.1 mm Hg, 95% confidence interval [CI] = -12.5 to -1.6 mm Hg; spray = -8.0 mm Hg, 95% CI = -13.4 to -2.5 mm Hg). On average, water significantly increased the fall in aortic systolic BP with nitrate tablets (-5.5 mm Hg, 95% CI = -10.9 to -0.1 mm Hg, p = 0.044) but did not significantly enhance the effect of nitrate spray (-2.8 mm Hg, 95% CI = -8.3 to 2.6 mm Hg). Water significantly increased the fall in aortic diastolic BP with tablets only (-2.9 mm Hg, 95% CI = -5.5 to -0.2), and had no significant effect on heart rate. Water had a consistently larger influence on the hemodynamic effects of nitrate tablets than on the effects of nitrate spray. Patients with a dry mouth will have an increased effect from sublingual nitrate tablets if they wet their mouth before using sublingual nitrate tablets. Water does not appear to assist in the action of sublingual spray.

Organic nitrates: new formulations and their clinical advantages

The organic nitrates have been used for more than a century in the management of patients with myocardial ischemia. The most commonly used agents at this time include nitroglycerin, isosorbide dinitrate, and isosorbide-5-mononitrate. These agents all exert their therapeutic effects through biodegradation to nitric oxide, which stimulates guanylate cyclase in vascular smooth muscle cells with the production of cyclic guanosine monophosphate. The latter induces vasodilation by reducing the availability of ionized calcium to the contractile proteins. Tolerance to the organic nitrates occurs when the agents are administered in an attempt to provide therapeutic effects throughout 24 hours each day. There are probably several mechanisms responsible for nitrate tolerance, but there is no evidence at this time that concurrent medications will modify the development of tolerance. The only available method at this time is to give these agents intermittently to provide a period of washout. In so doing, it is possible to provide therapeutic nitrate effects for approximately 12 hours throughout each 24-hour period.

Short- and long-term effects of antihypertensive drugs on arterial reflections, compliance, and impedance

This article reviews our work on the effects of different classes of antihypertensive agents on the hemodynamic alterations in essential human hypertension. Short-term studies were done during cardiac catheterization in young normotensive subjects (mean age, 33 years; range, 19 to 40) and several different age-matched (range, 25 to 53 years) groups of patients with essential hypertension. Aortic impedance, resistance, wave reflections, and compliance were calculated from high-fidelity recordings of ascending aortic pressure and flow signals during baseline and after nitroprusside, propranolol followed by phentolamine, phentolamine, captopril, and nifedipine, respectively, at doses sufficient to normalize blood pressure in each hypertensive group. Propranolol exacerbated all the hemodynamic parameters; these effects were only partially overcome by phentolamine. Among the other agents only phentolamine did not completely normalize compliance, and only captopril did not completely normalize wave reflections. The long-term study was a randomized, double-blind comparison of fosinopril and atenolol in 79 normotensive subjects and 79 essential hypertensive patients. Baseline 24-hour ambulatory blood pressures and carotid artery tonometry to index wave reflections were performed in all subjects and in hypertensive patients after 8 weeks of therapy. Both fosinopril and atenolol normalized blood pressure and lowered the elevated augmentation index, but fosinopril had a significantly larger effect than atenolol. Both short- and long-term beta-blockade did not have as beneficial an effect as the other agents. Thus, the differing hemodynamic effects of the various classes of antihypertensive agents might be a consideration in the choice of therapy.

Arterial hemodynamics in human hypertension. Effects of the calcium channel antagonist nifedipine

Previous studies have shown some distinct hemodynamic alterations in essential hypertension, including increased resistance, wave reflections, and pulse wave velocity and decreased arterial compliance. These abnormalities are completely normalized by nonspecific smooth muscle dilation with nitroprusside but not by combined alpha- and beta-adrenergic blockade or angiotensin-converting enzyme inhibition, suggesting an enhanced smooth muscle tone that cannot be attributed solely to the sympathetic nervous or renin-angiotensin systems. Since hypertensive patients have an enhanced calcium influx-dependent vasoconstriction, we performed the present study to examine the extent to which the dihydropyridine calcium channel antagonist nifedipine could normalize the hemodynamic abnormalities in essential hypertension. An essential hypertensive patient group was compared with a normotensive group similar in age, body size, and proportion of men and women. During diagnostic cardiac catheterization, ascending aortic micromanometer pressures and electromagnetic flows were measured at baseline and after sufficient sublingual nifedipine (mean, 24 mg) to normalize blood pressure. From the pressures and flows, aortic input impedance, wave reflection magnitude, and compliance were computed. In the hypertensive group, the hemodynamic alterations were indistinguishable from those summarized above. Nifedipine produced sufficient vasodilation to completely normalize all of these hemodynamic alterations, including wave reflections. From these results, together with those reported in our previous studies, it is clear that the various classes of antihypertensive agents affect hemodynamics differently. All are capable of decreasing blood pressure to normotensive levels, but only nitroprusside and nifedipine can also completely normalize all the other pulsatile hemodynamic alterations. Thus, these hemodynamic effects of the different classes of antihypertensive agents should be considered in choosing a therapeutic modality.

Aging is associated with endothelial dysfunction in healthy men years before the age-related decline in women

OBJECTIVES

This study assessed whether aging is associated with progressive endothelial dysfunction, whether the pattern of any age-related decline in vascular health is different in men and women and whether any gender difference is consistent with known changes in hormonal status.

BACKGROUND

Coronary and cerebrovascular disease are much less common in young and middle-aged women compared with men, although the gender difference in death from atherosclerosis is less marked after the menopause. Endothelial dysfunction is an early event in atherogenesis and is important in dynamic plaque stenosis in later life. The effect of aging on endothelial function in men and women, however, is not well known.

METHODS

We used high resolution ultrasound to study endothelium-dependent and endothelium-independent vascular responses. Brachial artery physiology was investigated in 238 subjects (103 men, 135 women; mean [+/- SD] age 38 +/- 17 years, range 15 to 72) with no known risk factors for atherosclerosis. The responses to reactive hyperemia (flow-mediated dilation, which is endothelium dependent) and to glyceryl trinitrate (an endothelium-independent dilator) were assessed for all the subjects and then for men and women separately.

RESULTS

On multivariate analysis for the whole group, reduced flow-mediated dilation was related to older age (r = -0.34, p < 0.0001). In men, flow-mediated dilation was preserved in subjects aged < or = 40 years but declined thereafter at 0.21%/year. In women, flow-mediated dilation was stable until the early 50s, after which it declined at 0.49%/year (p = 0.002 compared with men). In contrast, there was no significant change in the glyceryl trinitrate response with aging in either gender.

CONCLUSIONS

Aging is associated with progressive endothelial dysfunction in normal humans, and this appears to occur earlier in men than in women. In women, however, a steep decline commences at around the time of the menopause. This is consistent with a protective effect of estrogens on the arterial wall.

Short and long-acting oral nitrates for stable angina pectoris

Nitroglycerin (NTG) spray and sublingual tablets rapidly relieve an established attack of angina, and their infrequent use is not associated with the development of tolerance. Although, following a suitable nitrate-free interval, the first dose of oral, long-acting nitrates produces significant hemodynamic effects, increases angina free walking, and decreases exercise-induced ischemia, during continued long-term therapy tolerance limits their usefulness. Appropriate dosing regimens of controlled-release formulations of isosorbide dinitrate (ISDN) and controlled-release NTG during long-term therapy have not been established. Use of immediate-release formulation of 15-120 mg of ISDN in a qid regimen lead to a marked reduction in the size and duration of antianginal effects compared to the initial dose. Asymmetric tid therapy with 30 mg of ISDN (7 a.m., 1 p.m., and 6 p.m.) is also associated with the development of partial tolerance and appears to provide antianginal prophylaxis for only a period of 6 hours each day. Asymmetric bid therapy with ISDN at 7 a.m. and noon may give sustained effect but is supported by only a single, small study that did not examine effectiveness after the noon dose in long-term use. Isosorbide-5-mononitrate (IS-5-MN) has been the subject of more recent studies than other nitrates because of attempts to bring a number of products into the U.S. market. IS-5-MN in qid, tid, and standard bid (8 a.m. and 8 p.m.) dosing regimens produce tolerance. Asymmetric regimens of immediate-release IS-5-MN (10 and 20 mg) given bid (once in the morning and again 7 hours later) decrease the development of tolerance compared to symmetric regimens and produce an increased exercise duration after each dose of the day; the 20 mg bid dosing is more effective. Similarly, once-daily 120 and 240 mg controlled-release IS-5-MN does not produce tolerance and gives a sustained increase in daytime exercise duration. Both asymmetric bid immediate-release and once-daily controlled-release IS-5-MN preparations do not produce deterioration in exercise performance prior to the administration of the medication in the morning (i.e., no zero-hour effect). Further studies are needed to establish useful dosing regimens for ISDN, for controlled-release ISDN, and for controlled-release nitroglycerin. None of the dosing regimens of any oral, long-acting nitrate (including IS-5-MN) provide 24 hour antianginal and antiischemic effects.(ABSTRACT TRUNCATED AT 400 WORDS)

Plasma concentrations and hemodynamic effects of intravenous, sublingual, and aerosolized nitroglycerin in patients undergoing cardiac catheterization

Intravenous, sublingual, or aerosolized nitroglycerin was administered to 19 patients with coronary artery disease during clinically indicated cardiac catheterization. Eight blood samples were collected over 15 min from each patient, and analyzed for content of nitroglycerin, 1,2-glycerol dinitrate, and 1,3-glycerol dinitrate. Simultaneously, heart rate (HR), systolic blood pressure (SBP), and left ventricular end-diastolic pressure (LVEDP) were recorded. Plasma concentrations of nitroglycerin were highest after intravenous injection and lowest after sublingual tablets. Metabolite concentrations were highest after intravenous injection at early time-points; at later time-points, no between-group differences could be detected. SBP was minimally affected by intravenous nitroglycerin but was significantly reduced by sublingual and aerosolized formulations. Minor fluctuations in HR were observed in association with all three formulations. LVEDP was reduced by all three formulations of nitroglycerin but most rapidly by the intravenous form. Overall, no differences were detected in hemodynamic responses caused by sublingual and aerosolized nitroglycerin. Efficacy of sublingual and aerosolized nitroglycerin in patients undergoing cardiac catheterization is equivalent.

Arrhythmogenic right ventricular dysplasia: an uncommon cause of ventricular tachycardia in young and old?

Right ventricular dysplasia is a little understood condition and is almost certainly underdiagnosed as an important cause of recurrent ventricular tachycardia and sudden death. This report describes two patients with right ventricular dysplasia. Their clinical presentation reflects the remarkable diversity of the disease while the potentially life-threatening nature of their arrhythmias and their lack of response to medical treatment justified the antiarrhythmic surgical procedure of right ventricular disarticulation.

Issues in contemporary drug delivery. Part VI: Advanced cardiac drug formulations

OBJECTIVE

To identify and discuss the clinical utility of new delivery systems and formulations of cardiac drugs.

DATA SOURCES

Studies describing or evaluating new drug delivery systems for cardiac drugs were identified through a MEDLINE literature search.

STUDY SELECTION

All studies describing or evaluating new delivery systems for cardiac drugs were reviewed.

DATA EXTRACTION

Data were abstracted and evaluated by each author independently.

DATA SYNTHESIS

The most common oral sustained-release formulations include the wax-matrix system, the gastrointestinal therapeutic system (GITS), and the spheroidal oral drug absorption system (SODAS). The wax-matrix delivery system is limited by the occurrence of "dose-dumping." In a low-pH setting, the wax-matrix formulation may dissolve too rapidly, liberating the entire dose in a short period of time. The clinical relevance of this phenomenon is unknown. The GITS and SODAS formulations are less likely to be affected by pH and food. Nitroglycerin is available by many routes of administration. The topical patch forms are convenient to use, but are associated with the development of tolerance. A buccal formulation incorporates a relatively short onset of effect with a three- or four-times-daily dosing regimen. Although tolerance is less of a problem with buccal nitroglycerin than with topical nitrates, this formulation is less convenient to use because of buccal irritation and interference with eating and talking. A new spray formulation of nitroglycerin offers longer shelf-life storage stability and an easier mode of administration. The spray canister is stable for three years compared with 12 weeks for an opened bottle of sublingual nitroglycerin tablets. Sublingual administration of oral cardiac drugs offers the potential for a more rapid onset of effects. Although nifedipine is often given sublingually, objective data indicate that it is not absorbed buccally but rather in the stomach. It appears that the chew-and-swallow route is most appropriate for nifedipine. Captopril is absorbed sublingually but its efficacy has not been demonstrated. Transdermal clonidine improves compliance and is associated with fewer adverse effects than oral clonidine. Transdermal formulations of beta-blockers are currently being evaluated.

CONCLUSIONS

Further advancements in the development of novel delivery systems for cardiac drugs are expected in the future.

Limitations of transoesophageal echocardiography in patients with focal cerebral ischaemic events

OBJECTIVE

To investigate the detection rate of cardiac sources of embolism by transoesophageal echocardiography in patients with focal cerebral ischaemic events and to relate the echocardiographic findings to other clinical findings.

DESIGN

Prospective study with blinded analysis of the echocardiographic data and subsequent comparison with the other clinical findings.

SETTING

Regional cardiothoracic unit based in a teaching hospital.

PATIENTS

131 consecutive patients with focal ischaemic cerebral events (49 with a transient ischaemic attack, 77 with a cerebrovascular accident, and five with a retinal arterial embolus) referred for echocardiography.

INTERVENTIONS

Full M mode, cross sectional, Doppler, and contrast echocardiography by both the precordial and transoesophageal techniques.

RESULTS

Precordial echocardiography detected a cardiac abnormality in 72 patients. Transoesophageal echocardiography confirmed all the precordial findings (except left ventricular hypertrophy, which at present cannot be defined with this technique) and detected other abnormalities in a further 20 patients (18 with potential right-to-left shunts and two with valve vegetations). It also showed spontaneous contrast echoes in 27 of 28 patients with a large left atrium and showed atrial thrombus in three. Cardiac abnormalities were clinically detected in 53 patients, all of which were confirmed or documented by echocardiography. In the 78 patients with no clinically detectable cardiac abnormality six had mitral valve prolapse and one had a regional wall motion defect (identified by precordial echocardiography) and 17 had potential right-to-left shunts (11 of which were identified only by transoesophageal echocardiography).

CONCLUSIONS

Transoesophageal echocardiography is more sensitive than precordial echocardiography in detecting potential sources of embolism in these patients. However, except for the detection of a potential right-to-left shunt, the yield in patients with no cardiac abnormality is low. Moreover, the abnormalities detected in those with previously detected cardiac disease merely confirm the clinical diagnosis. Patients with left atrial spontaneous contrast echoes may benefit from anticoagulation but this requires further study. Until more data are available on this feature and on the role of potential right-to-left shunts in this population, the contribution of echocardiography, precordial or transoesophageal, remains limited.

The effect of nifedipine on the disposition of strontium gluconate used as a kinetic marker for calcium in healthy volunteers

1. We have studied the disposition of stable strontium after the intravenous administration of strontium gluconate to eight healthy male volunteers both in control conditions and while they were taking the calcium antagonist nifedipine 10 mg three times daily. 2. Nifedipine, presumably by its action in blocking voltage-operated calcium channels, altered the in vivo disposition of strontium, causing large reductions in the half-life and the apparent volume of distribution of strontium. Total and renal clearances of strontium were unaltered by nifedipine. 3. These results support our previous suggestion that the delineation of strontium disposition can be used as a means of studying calcium disposition in vivo in man, and of studying the effects of drugs and diseases on that disposition.

A dose-finding study of the hemodynamic effect of isosorbide dinitrate spray in congestive heart failure

A dose-finding study of the hemodynamic effect of a new formulation of isosorbide dinitrate (ISDN) spray was performed in 12 patients with chronic congestive heart failure. Doses of 1.25, 2.5, 5.0 mg and placebo, as 1 squirt, were randomly given to all patients. Hemodynamic measurements were performed by a Swan-Ganz catheter before and at 30 seconds and 1, 5, 10, 20 and 30 minutes after drug administration and every 30 minutes thereafter, until return of hemodynamic variables to baseline. Hemodynamic improvement evident as decreases in right-sided pressures and an increase in cardiac output was observed within 1 minute from administration of ISDN spray, and peaked at 5 minutes. Near maximal effect was achieved by the 2.5-mg dose. Thus, 2.5 mg of ISDN spray (new formulation) dose. Thus, 2.5 mg of ISDN spray (new formulation) produces rapid, near-maximal hemodynamic improvement in patients with congestive heart failure.

Comparative evaluation of a new formulation of isosorbide dinitrate oral spray and sublingual nitroglycerin tablets

The magnitude and time course of the hemodynamic effect of a new formulation of an aqueous solution of isosorbide dinitrate (ISDN) spray were compared with those of sublingual nitroglycerin (NTG) tablets in 12 patients with chronic congestive heart failure. The patients received, in a random order, ISDN spray, 2.5 mg, or sublingual NTG, 0.8 mg. Hemodynamic measurements were performed before and at 1, 3, 5, 10, 20, 30 and 60 minutes after each drug. The second drug was given only after return of the hemodynamic parameters to baseline, plus a washout period of 2 hours. The hemodynamic variables measured were comparable at baseline. Both drugs produced hemodynamic improvement including a decrease in pulmonary capillary wedge pressure (PCWP), right atrial pressure and systemic and pulmonary vascular resistances. Only ISDN spray significantly increased cardiac output. The onset of action of ISDN spray was significantly more rapid than that of NTG. This was primarily evident in the decrease in PCWP. With ISDN spray the decrease started at 1 minute after administration, and at 3 minutes a decrease of 8.6 mm Hg was already found. The corresponding value for sublingual NTG was 1.6 mm Hg. The difference was highly significant (p less than 0.02). The peak effect of ISDN spray on PCWP and right atrial pressure was greater than that of NTG. Thus, the onset of the hemodynamic effect of the new formulation of ISDN spray is much more rapid than that of sublingual NTG tablets. At the doses used, the magnitude of the effect of the ISDN spray on some of the hemodynamic variables is greater than that of sublingual NTG.

Hemodynamic and coronary vasodilative action of two nitroglycerin oral spray formulations

This study compared glycerol trinitrate (NTG) oral spray in a new hydrophilic formulation with a reference aerosol in a lipophilic base with respect to the time to onset of action on hemodynamics and on the coronary vasomotor tone. Differences in the profile of action between the two spray formulations were assessed in two groups of ten patients each. In each of the two groups the patients were randomly assigned to receive 0.8 mg of aerosolized NTG in either the hydrophilic or lipophilic base in double-blind fashion. The patients of group A had stable, exercise-induced angina pectoris, in whom responses to the sprays were evaluated under resting conditions. The patients of group B were suspicious of vasospastic or mixed form of angina pectoris, in whom the effects of the sprays were studied under diagnostic ergonovine provocation. The onset and extent of action of the sprays were assessed by serial measurements of hemodynamic parameters and repeat quantitative coronary angiography. The two formulations of NTG oral spray had a comparably potent coronary vasodilator effect in patients under resting conditions and under ergonovine provocation. As far as hemodynamic action is concerned, the new hydrophilic spray exerted its hemodynamic effect more rapidly than the lipophilic spray. Thus, the new NTG oral spray promises to afford therapeutic advantages for the relief of anginal attacks as well as hemodynamic unloading in congestive heart failure and acute pulmonary hypertension.

Nitroglycerine Lingual Aerosol in Prehospital Emergency Care,

Nitroglycerine (NTG) commonly is used in the prehospital emergency care setting for the treatment of chest pain suggestive of myocardial ischemia or infarction or for cardiac unloading in patients with presumed pulmonary edema. The usual form of this drug is as a 400 mcg tablet administered sublingually. Recently, NTG has become available as an aerosolized form (NTGA) in a multiple dose, pressurized canister containing 200 metered doses of 400 meg of NTG each. In this form, the drug is purported to be absorbed rapidly from the surface of the tongue.

In the field, we have noted that the sublingual tablet form of NTG occasionally remains undissolved following administration to patients complaining of chest pain. In each of these cases, clinically, the patients were unchanged on arrival at the receiving hospital and an intact tablet was discovered properly placed under the tongue. In an attempt to evaluate the ease of administration and clinical responses of patients with chest pain to the aerosolized form of the drug, we replaced NTG sublingual tablets on paramedic units in the Burbank system with the NTGA form.

Effect of theophylline on exercise-induced myocardial ischaemia

In a single-blind, placebo-controlled, randomised trial in 20 patients with stable angina pectoris, intravenous theophylline ethylenediamine (aminophylline), 7 mg/kg, increased the time to onset of angina by 46%, the heart-rate/blood-pressure product (an index of myocardial oxygen consumption) at 1 mm ST segment depression by 22%, and exercise duration by 24%. In a subsequent double-blind placebo-controlled trial in 8 patients a single oral dose of theophylline (375 mg) increased the time to onset of angina by 56%, the heart-rate/blood-pressure product at 1 mm ST segment depression by 22%, and the exercise duration by 35%. Infusion of theophylline ethylenediamine during angiography (10 patients) did not affect the diameter of epicardial coronary arteries. The beneficial effects of theophylline may be due to redistribution of coronary blood flow from non-ischaemic to ischaemic myocardium.

Nitroglycerin oral spray: evaluation of its coronary artery dilative action by quantitative angiography

Twenty patients were studied angiographically before and after administration of glyceryl trinitrate (NTG) spray at a single oral dose of 0.8 mg in either a hydrosoluble (NTG-h) or liposoluble (NTG-I) solution. The assessment was by a randomized double-blind trial involving quantitative coronary angiography and pharmacological stress testing using ergonovine maleate. The peak effect and duration of NTG-induced coronary dilatation were evaluated in 2 groups of 10 patients each, in whom NTG oral spray was given either under resting conditions (group A) or for the release of ergonovine-increased coronary vasomotor tone (group B). The study demonstrates that the 2 different galenic formulations of NTG spray are equally efficacious in dilating the conductance coronary arteries under both conditions. When NTG-h and NTG-I oral spray were given subsequent to ergonovine-testing, the diameters of extramural coronary arteries are not only reset to their dimensions at baseline but furthermore increase above resting values by 15.1% and 15.5%, respectively. Ergonovine-induced coronary vasoconstriction was released significantly for a period of at least 30 minutes. Both the NTG-h and NTG-I oral spray are potent coronary vasodilators in patients with increased coronary vasomotor tone.

Nitrates

Nitroglycerin and the long-acting nitrates are playing an increasingly important role in cardiovascular medicine. These agents are recommended in all of the various anginal syndromes and are as effective as the beta-blockers and calcium channel antagonists. There is a definite place for nitrate therapy in treating the complications of acute myocardial infarction. These drugs are also highly effective as unloading therapy in congestive heart failure. The mechanisms of action of the nitrates are reviewed in this article. Information is provided regarding nitrate efficacy in all the major clinical syndromes in which these drugs are used. Finally, appropriate dosing strategies are suggested that should eliminate the potential problem of nitrate tolerance.

Nitrate tolerance

The organic nitrates are the most widely used agents in the management of patients with angina pectoris. When initially administered by the oral route, the nitrates produce profound changes in systemic hemodynamics and significant and prolonged improvement in exercise duration. It has been shown that during short periods of regular oral nitrate administration, the hemodynamic, antiischemic and antianginal effects of the nitrates are greatly reduced. Thus, when initially administered, oral isosorbide dinitrate prolongs exercise duration for a period of several hours, but during sustained 4-times-daily therapy, exercise tolerance is improved for only 2 hours after administration. Studies with transdermal preparations of isosorbide dinitrate and nitroglycerin also show improvement during short-term administration for up to 8 hours, but after several days of once-daily therapy, the effects of these agents are similar to placebo. It is apparent that nitrate tolerance is a clinically relevant problem. Although tolerance develops rapidly during nitrate therapy, it is reversed promptly during nitrate-free periods. Oral nitrates maintain their antianginal effects when given 2 or 3 times daily with provision of a nitrate-free period. Studies are currently underway to investigate the effects of intermittent administration schedules with transdermal nitrate preparations.

Use of nitrates in unstable angina pectoris

The rationale for using intravenous nitrates in patients hospitalized with severe angina pectoris is that physiologic action is almost immediate. Many studies and clinical experience indicate that the use of this preparation results in a marked diminution of recurrent angina episodes in most patients. If adverse reactions such as severe hypotension or bradycardia occur, decreasing the dose or stopping it entirely corrects the problem. Intravenous nitroglycerin can be used in combination with other known antianginal agents, such as beta blockers and calcium antagonists. In clinical practice most patients are treated with nitrates and beta blockers or calcium antagonists because the combination of drugs may reduce ischemia and symptoms more than each drug used alone over a long period.

Glyceryl trinitrate (nitroglycerin) and the organic nitrates. Choosing the method of administration

Nitrate usage worldwide is on the increase as the indications for therapy expand. Present indications for nitrate therapy include chronic stable angina pectoris, unstable angina pectoris, complications of acute myocardial infarction, and 'unloading' therapy for acute and chronic congestive heart failure. Nitrates are also being used in the operating suite by anaesthesiologists to control systolic blood pressure during various surgical procedures. New nitrate delivery systems have recently become available which provide considerable dosing flexibility, further increasing the interest in this group of compounds. The dominant action of nitrates is a direct effect on vascular smooth muscle, producing vasodilation of the veins and arteries. These drugs decrease myocardial work by lowering systolic blood pressure, systemic vascular resistance, and reducing intracardiac dimensions. In addition, nitrates have a potent effect on cardiac preload as a result of systemic venodilatation. There is also some evidence that nitrates exert direct effects on the coronary circulation (vasodilatation of coronary arteries and coronary collateral vessels, and direct atherosclerotic stenosis dilatation). These actions may play a role in relieving myocardial ischaemia. Adverse sequelae of nitrate therapy are well known and serious adverse reactions are uncommon. Headache and dizziness are the most frequent side effects. Nitrate tolerance is a definite problem - present evidence indicates that long acting formulations, high doses, or frequent dosing regimens are particularly likely to induce vascular tolerance to nitrates. Consequently, provision of a nitrate-free interval has taken on increasing significance as a strategy to avoid tolerance. Nitrate delivery systems are numerous. Although availability varies from country to country, in most countries there are a wide variety of formulations of glyceryl trinitrate (nitroglycerin) available, including sublingual and oral tablets, oral spray, topical ointment as well as discs or patches for transdermal administration, a transmucosal tablet and an intravenous formulation. Similar formulations of isosorbide dinitrate, except buccal tablets, are available in some countries. Isosorbide 5-mononitrate, a potent metabolite of isosorbide dinitrate, is achieving increasing popularity as an antianginal drug. Optimum nitrate therapy requires a good understanding of the properties of the various formulations, particularly onset and duration of action and propensity to induce tolerance.(ABSTRACT TRUNCATED AT 400 WORDS)

New therapeutic modalities for the treatment of elderly patients with ischemic heart disease

In developing a treatment plan for elderly patients with ischemic heart disease, it is important to appreciate that the pathophysiologic process and aging influence the type of response produced by various drugs. The aging process also alters the way drugs are absorbed, distributed, and eliminated. Each of these variables must be considered in deciding which drugs should be used and how they should be administered.

Various administration forms of nitrates and their possibilities

This article reviews the development and pharmacokinetics of a number of new dosage formulations (e.g. transdermal patches and buccal tablets) and new active substances (e.g. isosorbide 5-mononitrate) which have recently been introduced to overcome some of the problems inherent in conventional formulations of organic nitrates.