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

Which patients with coronary artery disease should include oral nitrates on their discharge medication list?

BACKGROUND

Which patients with coronary artery disease (CAD) should have oral nitrates on their discharge medication list after coronary angiography (CAG)? To assess the relationship between oral nitrates included in the discharge medication list and major adverse cardiovascular events (MACEs) among CAD patients, we designed this retrospective cohort study.

METHODS

A total of 2979 CAD patients hospitalised in the Department of Cardiology, Affiliated Hospital of Jining Medical University from May 2013 to October 2015 were enrolled, grouped according to whether oral nitrates were included at discharge after CAG, and followed up for MACEs for a mean of 4.42 years after discharge. The primary endpoint was MACEs. Multivariate Cox proportional hazards models were used to analyses potential confounding factors. Stratified analysis was used to observe the relationship between oral nitrates and MACEs by different covariates.

RESULTS

The median follow-up time was 4.61 years, and 296 (9.94%) patients experienced MACEs. Multivariate Cox proportional hazards model analysis showed no association between oral nitrates on the discharge medication list and the occurrence of MACEs among patients with CAD (p > 0.05) after adjusting for some covariates, such as SYNTAX score (hazard ratio (HR): 1.18, 95% confidence interval (CI): 0.90-1.55, p = 0.2420). Stratified analysis revealed a higher incidence of MACEs among hypertensive patients prescribed oral nitrates at discharge (HR: 1.67, 95% confidence CI: 1.13-2.46, p = 0.0046). However, prescribing nitrates at discharge for patients with low uric acid levels increased the incidence of MACEs, which showed a possible trend towards significance (HR: 1.44, 95% CI: 0.99-2.09, p = 0.0525).

CONCLUSION

There was no association between oral nitrates included in the discharge medication list and the development of MACEs among patients with CAD after adjusting for some covariates, such as SYNTAX score. Oral nitrates after discharge for CAD patients combined with hypertension increased the occurrence of MACEs. Oral nitrates after discharge for CAD patients combined with low uric acid levels may increase theoccurrence of MACEs, and close monitoring for any adverse events is recommended.

A ketogenic diet lowers myocardial fatty acid oxidation but does not affect oxygen consumption: a study in overweight humans

OBJECTIVE

A ketogenic diet (KD) characterized by very low carbohydrate intake and high fat consumption may simultaneously induce weight loss and be cardioprotective. The "thrifty substrate hypothesis" posits that ketone bodies are more energy efficient compared with other cardiac oxidative substrates such as fatty acids. This work aimed to study whether a KD with presumed increased myocardial ketone body utilization reduces cardiac fatty acid uptake and oxidation, resulting in decreased myocardial oxygen consumption (MVO2 ).

METHODS

This randomized controlled crossover trial examined 11 individuals with overweight or obesity on two occasions: (1) after a KD and (2) after a standard diet. Myocardial free fatty acid (FFA) oxidation, uptake, and esterification rate were measured using dynamic [11 C]palmitate positron emission tomography (PET)/computed tomography, whereas MVO2 and myocardial external efficiency (MEE) were measured using dynamic [11 C]acetate PET.

RESULTS

The KD increased plasma β-hydroxybutyrate, reduced myocardial FFA oxidation (p < 0.01) and uptake (p = 0.03), and increased FFA esterification (p = 0.03). No changes were observed in MVO2 (p = 0.2) or MEE (p = 0.87).

CONCLUSIONS

A KD significantly reduced myocardial FFA uptake and oxidation, presumably by increasing ketone body oxidation. However, this change in cardiac substrate utilization did not improve MVO2 , speaking against the thrifty substrate hypothesis.

Tailoring the management of hypertension to comorbidities

PURPOSE OF REVIEW

In this article, we review the most current evidence for initiation and maintenance of various antihypertension (HTN) drug classes, including other misconceptions with respect to common comorbidities in patients with HTN.

RECENT FINDINGS

Although the currently available anti-HTN agents have broad applicability in treating HTN, additional agents, such as angiotensin receptor-neprilysin inhibitors and novel nonsteroidal mineralocorticoid antagonists, have recently gained clinical significance. In addition, there have been some anecdotal concerns regarding the adverse effects, indications, and risks of COVID-19 infection/mortality when using certain anti-HTN agents.

SUMMARY

Current guidelines currently address the treatment of primary HTN. However, isolated HTN is uncommon and often involves comorbid diseases that require specific regimentation. Several experimental medications are currently in late-stage trials showing potential superiority over current drugs that are available in the market.

Risk characterisation of constituents present in jamu to promote its safe use

Safety in use of jamu consumption, as part of traditional medicine from Indonesia, is dependent on the complete and adequate assessment of potential hazards and risks of the botanicals and botanical constituents included. This includes especially hazards and risks related to the presence in jamu of active pharmaceutical ingredients (APIs) as well as of constituents that are genotoxic and carcinogenic. The present review presents an overview of the current state-of-the art on these hazards and risks based on case reports on adulteration, and the actual detection of genotoxic and carcinogenic ingredients of concern in jamu. Based on the overview thus obtained, it appears that drug-adulteration presents important hazards responsible for potential adverse effects, due to overdosing. The potential hazards of exposure to APIs mainly relate to the presence of constituents that may cause liver damage, renal impairment, kidney failure, steroid dependence or genotoxicity and carcinogenicity. For these APIs, a risk characterisation was performed based on comparison of health-based guidance values (HBGVs) and exposure, while for the genotoxic carcinogens the margin of exposure (MOE) approach was used. Results of this risk characterisation should be used by risk managers to impose specification for constituents of health concern to protect consumers. It is concluded that to manage the risks identified and further improve the safety in use of jamu, a collaboration between farmers, manufacturer/producers, academia, government, health professionals, and consumers is indicated.

PDE-5 inhibitors in selected herbal supplements from the Ghanaian market for better erectile function as tested by a bioassay

Herbal supplements sold as 'all natural' on various markets in Accra (Ghana) and advertised as highly efficacious in treating erectile dysfunction (ED) were bought and analysed by a PDE-5 enzyme inhibition assay. The claimed efficacy of these products could be the result of inherent plant constituents, but also of intentionally added pharmaceuticals. Medically, ED is treated with potent inhibitors of the phosphodiesterase-5 (PDE-5) enzyme, as in the case of sildenafil. To test the efficacy of the Ghanaian supplements, extracts were made and tested using a PDE-Glo phosphodiesterase assay, a luminescent high-throughput screening (HTS) method. Results revealed that about 90% of the selected samples were able to inhibit PDE-5 activity to a high extent. Estimated concentrations in sildenafil equivalents ranged from traces to very high, with 25 samples (62.5%) pointing at daily doses higher than 25 mg sildenafil equivalents and 9 (22.5%) of these at doses higher than the maximal recommended daily intake of 100 mg sildenafil equivalents. Further investigations are needed to confirm if the observed effects are due to inherent plant constituents or merely the result of added synthetic PDE-5 enzyme inhibitors, especially because doses above 100 mg sildenafil equivalents per day may result in severe health risks.

Saudi Heart Association (SHA) guidelines for the management of heart failure

Heart failure (HF) is the leading cause of morbidity and mortality worldwide and negatively impacts quality of life, healthcare costs, and longevity. Although data on HF in the Arab population are scarce, recently developed regional registries are a step forward to evaluating the quality of current patient care and providing an overview of the clinical picture. Despite the burden of HF in Saudi Arabia, there are currently no standardized protocols or guidelines for the management of patients with acute or chronic heart failure. Therefore, the Heart Failure Expert Committee, comprising 13 local specialists representing both public and private sectors, has developed guidelines to address the needs and challenges for the diagnosis and treatment of HF in Saudi Arabia. The ultimate aim of these guidelines is to assist healthcare professionals in delivering optimal care and standardized clinical practice across Saudi Arabia.

Advances in small-molecule therapy for managing angina pectoris in the elderly

Introduction: As our population ages, the prevalence of angina is growing, leading to increased morbidity and decreased quality of life. The management of angina in the elderly is challenging due to drug intolerance and/or drug resistance as well as frailty. Over the past decades, many new therapeutic small molecules have been investigated for the management of angina. Although none of these studies have specifically focused on the therapies for the elderly, they offer promising new avenues for the treatment of angina in the elderly. Areas covered: Herein, the authors provide a review of the recently published literature on the use of small-molecule therapies for angina management in the elderly and provide a brief overview of these therapies. Expert opinion: A variety of therapeutic classes of existing and newer small molecules are emerging for the management of angina in the elderly. An individualized approach to the management of angina in this growing population is critical for good outcomes. Many small molecules are in their initial stages of clinical use, and further research should be conducted on their utility, especially in the elderly.

Acute ingestion of dietary nitrate increases muscle blood flow via local vasodilation during handgrip exercise in young adults

Dietary nitrate (NO3−) is converted to nitrite (NO2−) and can be further reduced to the vasodilator nitric oxide (NO) amid a low O₂ environment. Accordingly, dietary NO3− increases hind limb blood flow in rats during treadmill exercise; however, the evidence of such an effect in humans is unclear. We tested the hypothesis that acute dietary NO3− (via beetroot [BR] juice) increases forearm blood flow (FBF) via local vasodilation during handgrip exercise in young adults (n = 11; 25 ± 2 years). FBF (Doppler ultrasound) and blood pressure (Finapres) were measured at rest and during graded handgrip exercise at 5%, 15%, and 25% maximal voluntary contraction (MVC) lasting 4 min each. At the highest workload (25% MVC), systemic hypoxia (80% SaO₂) was induced and exercise continued for three additional minutes. Subjects ingested concentrated BR (12.6 mmol nitrate (n = 5) or 16.8 mmol nitrate (n = 6) and repeated the exercise bout either 2 (12.6 mmol) or 3 h (16.8 mmol) postconsumption. Compared to control, BR significantly increased FBF at 15% MVC (184 ± 15 vs. 164 ± 15 mL/min), 25% MVC (323 ± 27 vs. 286 ± 28 mL/min), and 25% + hypoxia (373 ± 39 vs. 343 ± 32 mL/min) and this was due to increases in vascular conductance (i.e., vasodilation). The effect of BR on hemodynamics was not different between the two doses of BR ingested. Forearm VO₂ was also elevated during exercise at 15% and 25% MVC. We conclude that acute increases in circulating NO3− and NO2− via BR increases muscle blood flow during moderate‐ to high‐intensity handgrip exercise via local vasodilation. These findings may have important implications for aging and diseased populations that demonstrate impaired muscle perfusion and exercise intolerance.

ALDH2 and Cardiovascular Disease

Aldehyde dehydrogenase 2 (ALDH2) is a non-cytochrome P450 mitochondrial aldehyde oxidizing enzyme. It is best known for its role in the metabolism of acetaldehyde, a common metabolite from alcohol drinking. More evidences have been accumulated in recent years to indicate a greater role of ALDH2 in the metabolism of other endogenous and exogenous aldehydes, especially lipid peroxidation-derived reactive aldehyde under oxidative stress. Many cardiovascular diseases are associated with oxidative stress and mitochondria dysfunction. Considering that an estimated 560 million East Asians carry a common ALDH2 deficient variant which causes the well-known alcohol flushing syndrome due to acetaldehyde accumulation, the importance of understanding the role of ALDH2 in these diseases should be highlighted. There are several unfavorable cardiovascular conditions that are associated with ALDH2 deficiency. This chapter reviews the function of ALDH2 in various pathological conditions of the heart in relation to aldehyde toxicity. It also highlights the importance and clinical implications of interaction between ALDH2 deficiency and alcohol drinking on cardiovascular disease among the East Asians.

Winner of the society for biomaterials young investigator award for the annual meeting of the society for biomaterials, April 11-14, 2018, Atlanta, GA: S-nitrosated poly(propylene sulfide) nanoparticles for enhanced nitric oxide delivery to lymphatic tissues

Nitric oxide (NO) is a therapeutic implicated for the treatment of diseases afflicting lymphatic tissues, which range from infectious and cardiovascular diseases to cancer. Existing technologies available for NO therapy, however, provide poor bioactivity within lymphatic tissues. In this work, we address this technology gap with a NO encapsulation and delivery strategy leveraging the formation of S-nitrosothiols on lymphatic-targeting pluronic-stabilized, poly(propylene sulfide)-core nanoparticles (SNO-NP). We evaluated in vivo the lymphatic versus systemic delivery of NO resulting from intradermal administration of SNO-NP benchmarked against a commonly used, commercially available small molecule S-nitrosothiol NO donor, examined signs of toxicity systemically as well as localized to the site of injection, and investigated SNO effects on lymphatic transport and NP uptake by lymph node (LN)-resident cells. Donation of NO from SNO-NP, which scaled in proportion to the total administered dose, enhanced LN accumulation by two orders of magnitude without substantially reducing lymphatic transport of NP or the viability and extent of NP uptake by LN-resident cells. Additionally, NO delivery by SNO-NP was accompanied by low-to-negligible NO accumulation in systemic tissues with no apparent inflammation. These results suggest the utility and selectivity of SNO-NP for the targeted treatment of NO-regulated diseases that afflict lymphatic tissues. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1463-1475, 2018.

The Role of Nitroglycerin and Other Nitrogen Oxides in Cardiovascular Therapeutics

The use of nitroglycerin in the treatment of angina pectoris began not long after its original synthesis in 1847. Since then, the discovery of nitric oxide as a biological effector and better understanding of its roles in vasodilation, cell permeability, platelet function, inflammation, and other vascular processes have advanced our knowledge of the hemodynamic (mostly mediated through vasodilation of capacitance and conductance arteries) and nonhemodynamic effects of organic nitrate therapy, via both nitric oxide-dependent and -independent mechanisms. Nitrates are rapidly absorbed from mucous membranes, the gastrointestinal tract, and the skin; thus, nitroglycerin is available in a number of preparations for delivery via several routes: oral tablets, sublingual tablets, buccal tablets, sublingual spray, transdermal ointment, and transdermal patch, as well as intravenous formulations. Organic nitrates are commonly used in the treatment of cardiovascular disease, but clinical data limit their use mostly to the treatment of angina. They are also used in the treatment of subsets of patients with heart failure and pulmonary hypertension. One major limitation of the use of nitrates is the development of tolerance. Although several agents have been studied for use in the prevention of nitrate tolerance, none are currently recommended owing to a paucity of supportive clinical data. Only 1 method of preventing nitrate tolerance remains widely accepted: the use of a dosing strategy that provides an interval of no or low nitrate exposure during each 24-h period. Nitric oxide's important role in several cardiovascular disease mechanisms continues to drive research toward finding novel ways to affect both endogenous and exogenous sources of this key molecular mediator.

Antianginal Therapy for Stable Ischemic Heart Disease

Chronic angina pectoris is associated with considerable morbidity and mortality, especially if treated suboptimally. For many patients, aggressive pharmacologic intervention is necessary in order to alleviate anginal symptoms. The optimal treatment of stable ischemic heart disease (SIHD) should be the prevention of angina and ischemia, with the goal of maximizing both quality and quantity of life. In addition to effective risk factor modification with lifestyle changes, intensive pharmacologic secondary prevention is the therapeutic cornerstone in managing patients with SIHD. Current guidelines recommend a multifaceted therapeutic approach with β-blockers as first-line treatment. Another important pharmacologic intervention for managing SIHD is nitrates. Nitrates can provide both relief of acute angina and can be used prophylactically before exposure to known triggers of myocardial ischemia to prevent angina. Additional therapeutic options include calcium channel blockers and ranolazine, an inhibitor of the late inward sodium current, that can be used alone or in addition to nitrates or β-blockers when these agents fail to alleviate symptoms. Ranolazine appears to be particularly effective for patients with microvascular angina and endothelial dysfunction. In addition, certain antianginal therapies are approved in Europe and have been shown to improve symptoms, including ivabradine, nicorandil, and trimetazidine; however, these have yet to be approved in the United States. Ultimately, there are several different medications available to the physician for managing the patient with SIHD having chronic angina, when either used alone or in combination. The purpose of this review is to highlight the most important therapeutic approaches to optimizing contemporary treatment in response to individual patient needs.

Vasodilator Therapy: Nitrates and Nicorandil

Nitrates have been used to treat symptoms of chronic stable angina for over 135 years. These drugs are known to activate nitric oxide (NO)-cyclic guanosine-3',-5'-monophasphate (cGMP) signaling pathways underlying vascular smooth muscle cell relaxation, albeit many questions relating to how nitrates work at the cellular level remain unanswered. Physiologically, the anti-angina effects of nitrates are mostly due to peripheral venous dilatation leading to reduction in preload and therefore left ventricular wall stress, and, to a lesser extent, epicardial coronary artery dilatation and lowering of systemic blood pressure. By counteracting ischemic mechanisms, short-acting nitrates offer rapid relief following an angina attack. Long-acting nitrates, used commonly for angina prophylaxis are recommended second-line, after beta-blockers and calcium channel antagonists. Nicorandil is a balanced vasodilator that acts as both NO donor and arterial K(+) ATP channel opener. Nicorandil might also exhibit cardioprotective properties via mitochondrial ischemic preconditioning. While nitrates and nicorandil are effective pharmacological agents for prevention of angina symptoms, when prescribing these drugs it is important to consider that unwanted and poorly tolerated hemodynamic side-effects such as headache and orthostatic hypotension can often occur owing to systemic vasodilatation. It is also necessary to ensure that a dosing regime is followed that avoids nitrate tolerance, which not only results in loss of drug efficacy, but might also cause endothelial dysfunction and increase long-term cardiovascular risk. Here we provide an update on the pharmacological management of chronic stable angina using nitrates and nicorandil.

Role of short-acting nitroglycerin in the management of ischemic heart disease

Nitroglycerin is the oldest and most commonly prescribed short-acting anti-anginal agent; however, despite its long history of therapeutic usage, patient and health care provider education regarding the clinical benefits of the short-acting formulations in patients with angina remains under-appreciated. Nitrates predominantly induce vasodilation in large capacitance blood vessels, increase epicardial coronary arterial diameter and coronary collateral blood flow, and impair platelet aggregation. The potential for the prophylactic effect of short-acting nitrates remains an under-appreciated part of optimal medical therapy to reduce angina and decrease myocardial ischemia, thereby enhancing the quality of life. Short-acting nitroglycerin, administered either as a sublingual tablet or spray, can complement anti-anginal therapy as part of optimal medical therapy in patients with refractory and recurrent angina either with or without myocardial revascularization, and is most commonly used to provide rapid therapeutic relief of acute recurrent angina attacks. When administered prophylactically, both formulations increase angina-free walking time on treadmill testing, abolish or delay ST segment depression, and increase exercise tolerance. The sublingual spray formulation provides several clinical advantages compared to tablet formulations, including a lower incidence of headache and superiority to the sublingual tablet in terms of therapeutic action and time to onset, while the magnitude and duration of vasodilatory action appears to be comparable. Furthermore, the sublingual spray formulation may be advantageous to tablet preparations in patients with dry mouth. This review discusses the efficacy and utility of short-acting nitroglycerin (sublingual spray and tablet) therapy for both preventing and aborting an acute angina attack, thereby leading to an improved quality of life.

Nitroglycerin tolerance in caveolin-1 deficient mice

Nitrate tolerance developed after persistent nitroglycerin (GTN) exposure limits its clinical utility. Previously, we have shown that the vasodilatory action of GTN is dependent on endothelial nitric oxide synthase (eNOS/NOS3) activity. Caveolin-1 (Cav-1) is known to interact with NOS3 on the cytoplasmic side of cholesterol-enriched plasma membrane microdomains (caveolae) and to inhibit NOS3 activity. Loss of Cav-1 expression results in NOS3 hyperactivation and uncoupling, converting NOS3 into a source of superoxide radicals, peroxynitrite, and oxidative stress. Therefore, we hypothesized that nitrate tolerance induced by persistent GTN treatment results from NOS3 dysfunction and vascular toxicity. Exposure to GTN for 48-72 h resulted in nitrosation and depletion (>50%) of Cav-1, NOS3 uncoupling as measured by an increase in peroxynitrite production (>100%), and endothelial toxicity in cultured cells. In the Cav-1 deficient mice, NOS3 dysfunction was accompanied by GTN tolerance (>50% dilation inhibition at low GTN concentrations). In conclusion, GTN tolerance results from Cav-1 modification and depletion by GTN that causes persistent NOS3 activation and uncoupling, preventing it from participating in GTN-medicated vasodilation.

Challenges with nitrate therapy and nitrate tolerance: prevalence, prevention, and clinical relevance

Nitrate therapy has been an effective treatment for ischemic heart disease for over 100 years. The anti-ischemic and exercise-promoting benefits of sublingually administered nitrates are well established. Nitroglycerin is indicated for the relief of an established attack of angina and for prophylactic use, but its effects are short lived. In an effort to increase the duration of beneficial effects, long-acting orally administered and topical applications of nitrates have been developed; however, following their continued or frequent daily use, patients soon develop tolerance to these long-acting nitrate preparations. Once tolerance develops, patients begin losing the protective effects of the long-acting nitrate therapy. By providing a nitrate-free interval, or declining nitrate levels at night, one can overcome or reduce the development of tolerance, but cannot provide 24-h anti-anginal and anti-ischemic protection. In addition, patients may be vulnerable to occurrence of rebound angina and myocardial ischemia during periods of absent nitrate levels at night and early hours of the morning, and worsening of exercise capacity prior to the morning dose of the medication. This has been a concern with nitroglycerin patches but not with oral formulations of isosorbide-5 mononitrates, and has not been adequately studied with isosorbide dinitrate. This paper describes problems associated with nitrate tolerance, reviews mechanisms by which nitrate tolerance and loss of efficacy develop, and presents strategies to avoid nitrate tolerance and maintain efficacy when using long-acting nitrate formulations.

Advances in targeting cyclic nucleotide phosphodiesterases

Cyclic nucleotide phosphodiesterases (PDEs) catalyse the hydrolysis of cyclic AMP and cyclic GMP, thereby regulating the intracellular concentrations of these cyclic nucleotides, their signalling pathways and, consequently, myriad biological responses in health and disease. Currently, a small number of PDE inhibitors are used clinically for treating the pathophysiological dysregulation of cyclic nucleotide signalling in several disorders, including erectile dysfunction, pulmonary hypertension, acute refractory cardiac failure, intermittent claudication and chronic obstructive pulmonary disease. However, pharmaceutical interest in PDEs has been reignited by the increasing understanding of the roles of individual PDEs in regulating the subcellular compartmentalization of specific cyclic nucleotide signalling pathways, by the structure-based design of novel specific inhibitors and by the development of more sophisticated strategies to target individual PDE variants.

Attenuated response of L-type calcium current to nitric oxide in atrial fibrillation

AIM

Nitric oxide (NO) synthesized by cardiomyocytes plays an important role in the regulation of cardiac function. Here, we studied the impact of NO signalling on calcium influx in human right atrial myocytes and its relation to atrial fibrillation (AF).

METHODS AND RESULTS

Right atrial appendages (RAAs) were obtained from patients in sinus rhythm (SR) and AF. The biotin-switch technique was used to evaluate endogenous S-nitrosylation of the α1C subunit of L-type calcium channels. Comparing SR to AF, S-nitrosylation of Ca(2+) channels was similar. Direct effects of the NO donor S-nitroso-N-acetyl-penicillamine (SNAP) on L-type calcium current (ICa,L) were studied in cardiomyocytes with standard voltage-clamp techniques. In SR, ICa,L increased with SNAP (100 µM) by 48%, n/N = 117/56, P < 0.001. The SNAP effect on ICa,L involved activation of soluble guanylate cyclase and protein kinase A. Specific inhibition of phosphodiesterase (PDE)3 with cilostamide (1 µM) enhanced ICa,L to a similar extent as SNAP. However, when cAMP was elevated by PDE3 inhibition or β-adrenoceptor stimulation, SNAP reduced ICa,L, pointing to cGMP-cAMP cross-regulation. In AF, the stimulatory effect of SNAP on ICa,L was attenuated, while its inhibitory effect on isoprenaline- or cilostamide-stimulated current was preserved. cGMP elevation with SNAP was comparable between the SR and AF group. Moreover, the expression of PDE3 and soluble guanylate cyclase was not reduced in AF.

CONCLUSION

NO exerts dual effects on ICa,L in SR with an increase of basal and inhibition of cAMP-stimulated current, and in AF NO inhibits only stimulated ICa,L. We conclude that in AF, cGMP regulation of PDE2 is preserved, but regulation of PDE3 is lost.

Sildenafil and analogous phosphodiesterase type 5 (PDE-5) inhibitors in herbal food supplements sampled on the Dutch market

Herbal food supplements, claiming to enhance sexual potency, may contain deliberately added active pharmacological ingredients (APIs) that can be used for the treatment of erectile dysfunction (ED). The aim of this study was to determine whether herbal food supplements on the Dutch market indeed contain APIs that inhibit phosphodiesterase type 5 (PDE-5) inhibitors, such as sildenafil and analogous PDE-5 inhibitors. Herbal food supplements intended to enhance sexual potency (n = 71), and two soft drinks, were sampled from 2003 up to and including 2012. In 23 herbal supplements, nine different PDE-5 inhibitors were identified; in a few cases (n = 3), more than one inhibitor was indentified. The presence of these APIs was however not stated on the label. The concentrations of PDE-5 inhibitors per dose unit were analysed. Furthermore, the potential pharmacologically active properties of the detected PDE-5 inhibitors were estimated by using data from the scientific and patent literature regarding (1) in vitro PDE-5 activity, (2) reported effective doses of registered drugs with PDE-5 inhibitor activity and (3) similarity to other structural analogues. It was concluded that 18 of the 23 herbal food supplements, when used as recommended, would have significant pharmacological effects due to added APIs. Adequate use of existing regulation and control measures seems necessary to protect consumers against the adverse effects of these products.

Transdermal glyceryl trinitrate as an effective adjunctive treatment with artemether for late-stage experimental cerebral malaria

Cerebral malaria (CM) is associated with low nitric oxide (NO) bioavailability, cerebrovascular constriction, occlusion, and hypoperfusion. Administration of exogenous NO partially prevents the neurological syndrome and associated vascular pathology in an experimental CM (ECM) mouse model. In this study, we evaluated the effects of transdermal glyceryl trinitrate in preventing ECM and, in combination with artemether, rescuing late-stage ECM mice from mortality. The glyceryl trinitrate and/or artemether effect on survival and clinical recovery was evaluated in C57BL/6 mice infected with P. berghei ANKA. NO synthase (NOS) expression in mouse brain was determined by Western blots. Mean arterial pressure (MAP) and pial arteriolar diameter were monitored using a tail-cuff blood pressure system and a cranial window preparation, respectively. Preventative administration of glyceryl trinitrate at 0.025 mg/h decreased ECM mortality from 67 to 11% and downregulated inducible NOS expression in the brain. When administered as adjunctive rescue therapy with artemether, glyceryl trinitrate increased survival from 47 to 79%. The adjunctive therapy caused a sustained reversal of pial arteriolar vasoconstriction in ECM mice, an effect not observed with artemether alone. Glyceryl trinitrate induced a 13% decrease in MAP in uninfected mice but did not further affect MAP in hypotensive ECM mice. Glyceryl trinitrate, when combined with artemether, was an effective adjunctive rescue treatment for ECM. This treatment ameliorated pial arteriolar vasospasm and did not significantly affect MAP. These results indicate that transdermal glyceryl trinitrate has potential to be considered as a candidate for adjunctive therapy for CM.