Topical minoxidil: cardiac effects in bald man

Clinical Studies Using Topical Melatonin

Melatonin is ubiquitously present in all animals and plants, where it exerts a variety of physiological activities thanks to its antioxidant properties and its key role as the first messenger of extracellular signaling functions. Most of the clinical studies on melatonin refer to its widespread oral use as a dietary supplement to improve sleep. A far smaller number of articles describe the clinical applications of topical melatonin to treat or prevent skin disorders by exploiting its antioxidant and anti-inflammatory activities. This review focuses on the clinical studies in which melatonin was applied on the skin as a photoprotective, anti-aging, or hair growth-promoting agent. The methodologies and results of such studies are discussed to provide an overall picture of the state of the art in this intriguing field of research. The clinical studies in which melatonin was applied on the skin before exposure to radiation (UV, sunlight, and high-energy beams) were all characterized by an appropriate design (randomized, double-blind, and placebo-controlled) and strongly support its clinical efficacy in preventing or reducing skin damage such as dermatitis, erythema, and sunburn. Most of the studies examined in this review do not provide a clear demonstration of the efficacy of topical melatonin as a skin anti-aging or as a hair growth-promoting agent owing to limitations in their design and/or to the use of melatonin combined with extra active ingredients, except for one trial that suggests a possible beneficial role of melatonin in treating some forms of alopecia in women. Further research efforts are required to reach definitive conclusions concerning the actual benefits of topical melatonin to counteract skin aging and hair loss.

Pharmacological Management of Pattern Hair Loss

Pattern hair loss (PHL) is a condition that worsens with time and the only way it can be slowed down is with pharmacological intervention. Pharmacological treatments for PHL, from an evidenced-based perspective with respect to safety and efficacy, are limited to only two drugs, minoxidil and finasteride. However, there are a host of drugs being used, off-label with limited evidence. This article attempts to review the literature on this topic, and the authors add to this, with their experience of over two decades on incorporating pharmacologic treatments along with hair transplantation in their management of PHL.

Retinal artery occlusion as a probable idiosyncratic reaction to topical minoxidil: a case report

BACKGROUND

Minoxidil hair formulation is commonly used for the treatment of male or female androgenic alopecia. This over-the-counter product is considered safe, but should be used with caution. Ocular side effects following topical minoxidil use are rarely reported. In this paper, we report a rare case of inferior hemiretinal artery occlusion possibly caused by topical 5% minoxidil treatment.

CASE DESCRIPTION

A 21-year-old Asian Indian male presented to the retina clinic with sudden onset blurring of vision and superior visual field loss in the right eye since morning. He was diagnosed with androgenic alopecia and was on treatment with topical 5% minoxidil spray twice a day for the last 3 years. On examination, his corrected distance visual acuity was 6/6, N6 in both eyes. Anterior segment examination and intraocular pressure in both eyes and left eye fundus were within normal limits. Right eye fundus examination showed features suggestive of inferior hemiretinal artery occlusion, which were confirmed on fluorescein angiography and optical coherence tomography. A detailed systemic evaluation and investigations (blood pressure, random blood sugar, hematological and coagulation profile, serum homocysteine level, Mantoux test, chest x-ray, cardiac two-dimensional echography, thyroid function test, and immunological profile) did not detect any abnormalities. The ocular condition and its visual prognosis were explained to the patient, and he was asked to review after 4 weeks.

CONCLUSION

Though there is no definite cause-outcome relationship between topical minoxidil use and retinal artery occlusion development, this possibility should be kept in mind when observing retinal vascular occlusion cases with concurrent use of topical minoxidil.

Topical Minoxidil Exposures and Toxicoses in Dogs and Cats: 211 Cases (2001-2019)

Topical minoxidil is a medication for hair loss, initially available in the United States by prescription only and available since 1996 as an over-the-counter product. To determine the epidemiology of minoxidil exposures and toxicoses in dogs and cats, 211 dog and cat cases with topical minoxidil exposure were identified from the American Society for the Prevention of Cruelty to Animals Animal Poison Control Center database. In 87 cases with clinical signs of toxicosis (62 cats, 25 dogs), case narratives were reviewed and coded for exposure-related circumstances. Unintentional delivery, especially while pet owners applied minoxidil for his/her own hair loss (e.g., pet licked owner's skin or pillowcase, pet was splashed during a medication spill), was the most common cat exposure circumstance. Exploratory behavior (e.g., searching through trash) was the most common dog exposure circumstance. Clinical signs occurred in dogs and cats even with low exposure amounts, such as drops or licks. In patients that developed clinical signs, most developed moderate or major illness (56.0% dogs, 59.7% cats). Death occurred in 8/62 (12.9%) cats that developed clinical signs after the pet owner's minoxidil use. Pet owners should be educated on the risk of dog and cat toxicosis from accidental minoxidil exposure.

Neural progenitor cell-derived nanovesicles promote hair follicle growth via miR-100

BACKGROUND

Accumulating evidence shows that mesenchymal stem cell-derived extracellular vesicles (EVs) hold great promise to promote hair growth. However, large-scale production of EVs is still a challenge. Recently, exosome-mimetic nanovesicles (NV) prepared by extruding cells have emerged as an alternative strategy for clinical-scale production. Here, ReNcell VM (ReN) cells, a neural progenitor cell line was serially extruded to produce NV.

RESULTS

ReN-NV were found to promote dermal papilla cell (DPC) proliferation. In addition, in a mouse model of depilation-induced hair regeneration, ReN-NV were injected subcutaneously, resulting in an acceleration of hair follicle (HF) cycling transition at the site. The underlying mechanism was indicated to be the activation of Wnt/β-catenin signaling pathway. Furthermore, miR-100 was revealed to be abundant in ReN-NV and significantly up-regulated in DPCs receiving ReN-NV treatment. miR-100 inhibition verified its important role in ReN-NV-induced β-catenin signaling activation.

CONCLUSION

These results provide an alternative agent to EVs and suggest a strategy for hair growth therapy.

The hydroxypropyl-β-cyclodextrin-minoxidil inclusion complex improves the cardiovascular and proliferative adverse effects of minoxidil in male rats: Implications in the treatment of alopecia

The efficacy of minoxidil (MXD) ethanolic solutions (1%-5% w/v) in the treatment of androgenetic alopecia is limited by adverse reactions. The toxicological effects of repeated topical applications of escalating dose (0.035%-3.5% w/v) and of single and twice daily doses (3.5% w/v) of a novel hydroxypropyl-β-cyclodextrin MXD GEL formulation (MXD/HP-β-CD) and a MXD solution were investigated in male rats. The cardiovascular effects were evaluated by telemetric monitoring of ECG and arterial pressure in free-moving rats. Ultrasonographic evaluation of cardiac morphology and function, and histopathological and biochemical analysis of the tissues, were performed. A pharmacovigilance investigation was undertaken using the EudraVigilance database for the evaluation of the potential cancer-related effects of topical MXD. Following the application of repeated escalating doses of MXD solution, cardiac hypertrophy, hypotension, enhanced serum natriuretic peptides and K+ -ion levels, serum liver biomarkers, and histological lesions including renal cancer were observed. In addition, the administration of a twice daily dose of MXD solution, at SF rat vs human = 311, caused reductions in the systolic, diastolic, and mean blood pressure of the rats (-30.76 ± 3%, -28.84 ± 4%, and -30.66 ± 5%, respectively, vs the baseline; t test P < .05). These effects were not reversible following washout of the MXD solution. Retrospective investigation showed 32 cases of cancer associated with the use of topical MXD in humans. The rats treated with MXD HP-β-CD were less severely affected. MXD causes proliferative adverse effects. The MXD HP-β-CD inclusion complex reduces these adverse effects.

A combination of pyridine-2, 4-dicarboxylic acid diethyl ester and resveratrol stabilizes hypoxia-inducible factor 1-alpha and improves hair density in female volunteers

OBJECTIVE

The aim of this study was first to demonstrate that a combination of pyridine-2, 4-dicarboxylic acid diethyl ester and resveratrol could synergize in vitro on biological pathways associated with hair growth and then to demonstrate the benefit on hair density in a clinical study.

METHODS

The effects of pyridine-2, 4-dicarboxylic acid diethyl ester and resveratrol directly on the hypoxic inducible factor-1α protein (HIF-1α) and related genes expression were demonstrated on keratinocytes in culture in vitro using western-blot analysis and real time quantitative polymerase chain reaction analysis. The effect of resveratrol against oxidative stress induced by hydrogen peroxide treatment was studied in hair follicle and hair matrix cells in vitro using the sensitive probe Dichloro-dihydro-fluorescein diacetate (DCFH-DA). Finally, a randomized clinical study on hair density was conducted on 79 Caucasian female subjects to assess the effect of this combination of actives.

RESULTS

Pyridine-2, 4-dicarboxylic acid diethyl ester and resveratrol stabilized HIF-1a protein and increased the expression of HIF-1α target genes. Resveratrol significantly reduced the oxygen peroxide-induced oxidative stress generated in hair follicle and hair matrix cells. The clinical study showed that a topical treatment with the combination significantly increased the hair density on women from 1.5 months.

CONCLUSION

In addition to the antioxidant properties of resveratrol, the association of pyridine-2, 4-dicarboxylic acid diethyl ester and resveratrol revealed a synergistic effect on the HIF-1α pathway. The results of the clinical study confirmed the importance of such a combination to increase the hair density.

Clinical cosmeceutical repurposing of melatonin in androgenic alopecia using nanostructured lipid carriers prepared with antioxidant oils

BACKGROUND

The present work aims to formulate nanostructured lipid carriers (NLCs) exhibiting high skin deposition and high inherent antioxidant potential to repurpose the use of melatonin hormone and some antioxidant oils in the treatment of androgenic alopecia (AGA).

RESEARCH DESIGN AND METHODS

NLCs were characterized for their size, charge, drug entrapment, anti-oxidant potential, physical stability, in vitro release, surface morphology, and ex-vivo skin deposition. Their merits were clinically tested on patients suffering from AGA by calculating the degree of improvement, conduction of hair pull test, histometric assessment, and dermoscopic evaluation.

RESULTS

Results revealed that melatonin NLCs showed nanometer size, negatively charged surface, high entrapment efficiency, and high anti-oxidant potential, in addition to sustained release for 6 h. Furthermore, NLCs displayed good storage stability and they were able to increase the skin deposition of melatonin 4.5-folds in stratum corneum, 7-folds in epidermis, and 6.8-folds in the dermis compared to melatonin solution. Melatonin NLCs displayed more clinically desirable results compared to the melatonin solution in AGA patients, manifested by increased hair density and thickness and decreased hair loss.

CONCLUSIONS

The aforementioned system was shown to be a very promising treatment modality for AGA, which is worthy of futuristic experimentation.

Efficacy of non-surgical treatments for androgenetic alopecia: a systematic review and network meta-analysis

Androgenetic alopecia, or male/female pattern baldness, is the most common type of progressive hair loss disorder. The aim of this study was to review recent advances in non-surgical treatments for androgenetic alopecia and identify the most effective treatments. A network meta-analysis (NMA) was conducted of the available literature of the six most common non-surgical treatment options for treating androgenetic alopecia in both men and women; dutasteride 0.5 mg, finasteride 1 mg, low-level laser therapy (LLLT), minoxidil 2%, minoxidil 5% and platelet-rich plasma (PRP). Seventy-eight studies met the inclusion criteria, and 22 studies had the data necessary for a network meta-analysis. Relative effects show LLLT as the superior treatment. Relative effects show PRP, finasteride 1 mg (male), finasteride 1 mg (female), minoxidil 5%, minoxidil 2% and dutasteride (male) are approximately equivalent in mean change hair count following treatment. Minoxidil 5% and minoxidil 2% reported the most drug-related adverse events (n = 45 and n = 23, respectively). The quality of evidence of minoxidil 2% vs. minoxidil 5% was high; minoxidil 5% vs. placebo was moderate; dutasteride (male) vs. placebo, finasteride (female) vs. placebo, minoxidil 2% vs. placebo and minoxidil 5% vs. LLLT was low; and finasteride (male) vs. placebo, LLLT vs. sham, PRP vs. placebo and finasteride vs. minoxidil 2% was very low. Results of this NMA indicate the emergence of novel, non-hormonal therapies as effective treatments for hair loss; however, the quality of evidence is generally low. High-quality randomized controlled trials and head-to-head trials are required to support these findings and aid in the development of more standardized protocols, particularly for PRP. Regardless, this analysis may aid physicians in clinical decision-making and highlight the variety of non-surgical hair restoration options for patients.

A hairy fall: syncope resulting from topical application of minoxidil

We describe the case of a young man who developed syncope after using a high strength formulation of topical minoxidil as a hair growth restorer. Other potential cardiovascular and endocrine causes were excluded, and his symptoms resolved on discontinuation of the product. While syncope is a recognised side effect of using this powerful systemic antihypertensive agent, few cases are documented in the literature, which we illustrate in our discussion.

Topical valproic acid increases the hair count in male patients with androgenetic alopecia: a randomized, comparative, clinical feasibility study using phototrichogram analysis

Valproic acid (VPA), a widely used anticonvulsant, inhibits glycogen synthase kinase 3β and activates the Wnt/β-catenin pathway, which is associated with hair growth cycle and anagen induction. To assess the efficacy of topical VPA for treating androgenetic alopecia (AGA), we performed a randomized, double-blind, placebo-controlled clinical trial. Male patients with moderate AGA underwent treatment with either VPA (sodium valproate, 8.3%) or placebo spray for 24 weeks. The primary end-point for efficacy was the change in hair count during treatment, which was assessed by phototrichogram analysis. Of the 40 patients enrolled in the study, 27 (n = 15, VPA group; n = 12, placebo group) completed the entire protocol with good compliance. No statistical differences in age, hair loss duration and total hair count at baseline were found between the groups. The mean change in total hair count was significantly higher in the VPA group than in the placebo group (P = 0.047). Both groups experienced mostly mild and self-limited adverse events, but their differences in prevalence rates were similar between the two groups (P = 0.72). A subject treated with topical VPA developed ventricular tachycardia, but it did not seem to be related to the VPA spray. Topical VPA increased the total hair counts of our patients; therefore, it is a potential treatment option for AGA.

Effect of topically applied minoxidil on the survival of rat dorsal skin flap

BACKGROUND

Flap necrosis still is a challenging problem in reconstructive surgery that results in irreversible tissue loss. This study evaluated the effect of topically applied minoxidil on angiogenesis and survival of a caudally based dorsal rat skin flap.

METHODS

For this study, 24 male Wistar rats were randomly divided into three groups of eight each. A caudally based dorsal skin flap with the dimensions of 9 × 3 cm was raised. After elevation of the flaps, they were sutured back into their initial positions. In group 1 (control group), 1 ml of isotonic saline was applied topically to the flaps of all the animals for 14 days. In group 2, minoxidil solution was spread uniformly over the flap surface for 7 days after the flap elevation. In group 3, minoxidil solution was applied topically to the flap surface during a 14-day period. On day 7 after the flap elevation, the rats were killed. The average area of flap survival was determined for each rat. Subdermal vascular architecture and angiogenesis were evaluated under a light microscope after two full-thickness skin biopsy specimens had been obtained from the midline of the flaps.

RESULTS

The lowest flap survival rate was observed in group 1, and no difference was observed between groups 1 and 2. Compared with groups 1 and 2, group 3 had a significantly increased percentage of flap survival (P < 0.05). Intense and moderate angiogenesis also was observed respectively at the proximal and distal areas of the flaps in group 3.

CONCLUSIONS

The results of this experiment seem to show that the early effect of minoxidil is vasodilation and that prolonged use before flap elevation leads to angiogenesis, increasing flap viability.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Topical absorption and systemic toxicity

Dermal absorption of some chemicals and drugs can cause systemic toxicity. We evaluated several case reports from the past decade, which discuss the dermal absorption of a specific chemical and potential local and systemic effects. We focused on herbicide and pesticide exposure along with exposure to cutaneous medication, occupational contact, and cosmeceutical exposure. Although causality cannot be established in most cases, it is critical to be aware of the possible effects of topical absorption that may not be immediately apparent. We recommended further studies on specific chemicals to ascertain causality and determine the highest exposure level with no observed adverse affect level (NOAEL) and the reference dose (RfD). Post-marketing epidemiology data in most geographical areas are markedly limited. A weak link in public health resides in the inadequate reporting and workup of alleged chemically related adverse effects. This arena mandates a re-thinking of how to increase this reporting, and workup, as a backup to our preclinical and clinical studies. Public awareness and funding will be rewarded by increased evidence to backup pre-approval pre-marketing studies.

Cardiac output and associated left ventricular hypertrophy in pediatric chronic kidney disease

A significant number of children with chronic kidney disease (CKD) have eccentric left ventricular hypertrophy (LVH), suggesting the role of preload overload. Therefore, we hypothesized that increased cardiac output (CO) might be a contributing factor for increased left ventricular mass index (LVMI) in these children. Patients aged 6-20 years with CKD stages 2-4 were enrolled. Echocardiograms were performed to assess LV function and geometry at rest and during exercise. Heart rate, stroke volume, and CO were also assessed at rest and during exercise. Twenty-four-hour ambulatory blood pressure (AMBP) monitoring was performed. Of the patients enrolled in this study, 17% had LVH. Increased stroke volume and CO were observed in patients with LVH compared to patients without LVH. Univariate analysis revealed significant positive associations between LVMI and CO, stroke volume, body mass index, pulse pressure from mean 24-h AMBP, and mean 24-h systolic BP load. No association with heart rate, age, parathyroid hormone, glomerular filtration rate, or anemia was observed. Only CO (beta = 1.98, p = 0.0005) was independently associated with increased LVMI in multivariate modeling (model R (2) = 0.25). The results of this study suggest that increased CO might predispose to increased LVMI in pediatric patients with CKD. Adaptations may be required to meet increased metabolic demand in these patients.

Minoxidil: an underused vasodilator for resistant or severe hypertension

Minoxidil is a direct vasodilator introduced in the early 1970s for the treatment of hypertension. It is capable of reducing blood pressure in most persons with resistant hypertension where therapy has failed with multidrug regimens. Minoxidil's effect can be limited because of an increase in pulse rate and/or sodium (and water) retention. The latter may prove quite debilitating in some patients. Thus, minoxidil is generally administered with both a diuretic and an agent that can keep pulse rate in check, such as a beta blocker or a combined alpha-beta blocker. The prominent tachycardia with minoxidil can aggravate myocardial ischemia and, if long-standing, leads to left ventricular hypertrophy. Minoxidil has a particularly annoying side effect of hypertrichosis that may limit its use, particularly among women. Minoxidil use is infrequently associated with the idiosyncratic onset of a pericardial effusion. If a patient's hypertension is severe enough to warrant minoxidil therapy, a hypertension specialist should probably become involved in the patient's care. The use of this medication should be limited in view of the availability of effective agents with fewer side effects. There is, however, a place for minoxidil in the treatment of resistant hypertension especially in patients with advanced renal disease.

Topically applied minoxidil may cause fetal malformation: A case report

BACKGROUND

Minoxidil is a K(+) channel opener able to cause relaxation of vascular smooth muscles and modify cell growth and cell fate or migration. It is now widely used for its hair growth promoting effects. When locally applied, it is absorbed through the skin and may have systemic pharmacological effects.

CASE

A 28-year-old white pregnant woman daily applied minoxidil 2% to her scalp because of hair loss. At the 22nd gestational week, after a routine ultrasound test showing significant brain, heart, and vascular malformations of the fetus, pregnancy was interrupted. The placenta had numerous ischemic areas and a discrepancy between gestational age and villi maturation. In the villi, capillaries were increased in number, significantly enlarged, and excessively marginalized. The fetus' heart was increased in volume and had a globose shape, the aorta had a distal stenosis. The sigmoid colon was significantly increased in length and a mesentery commune was present. The brain had enlarged ventricles and abundant hemorrhages. Histological examination showed areas of demyelinization with gliosis, signs of excessive and inappropriate angiogenesis, and capillary rearrangement.

CONCLUSIONS

Further knowledge on minoxidil-induced fetal toxicity would be beneficial before allowing its use in pregnant women.

Effects of minoxidil on ischemia-induced mechanical and metabolic dysfunction in dog myocardium

Effects of minoxidil on ischemia-induced myocardial mechanical and metabolic dysfunction were examined in anesthetized open-chest dogs. A regional portion of the left ventricle was made ischemic for 20 min by ligating the left anterior descending coronary artery, and then reperfused for 120 min. Dimethylsulfoxide or minoxidil (0.3, or 1.0 mg/kg) was injected intravenously 10 min before ligation. Ischemia decreased regional myocardial contraction, and reperfusion recovered it but incompletely. Myocardial metabolic derangement was observed during ischemia, such as decreases in the myocardial levels of ATP and creatine phosphate. These metabolic changes caused by ischemia were restored by reperfusion. Minoxidil injection at 0.3 and 1.0 mg/kg significantly decreased blood pressures but increased coronary flow. Pretreatment with minoxidil significantly enhanced the recovery of myocardial contraction during reperfusion after ischemia. The levels of ATP and creatine phosphate in the ischemic myocardium were significantly preserved by minoxidil at 0.3 mg/kg. No significant effect of minoxidil on the metabolism was observed in the 120 min reperfused myocardium. In conclusion, minoxidil improved the mechanical dysfunction in the reperfused heart and the drug at low dose preserved high-energy phosphates during ischemia.

Monotherapy versus combination therapy as first line treatment of uncomplicated arterial hypertension

Mild to moderate hypertension still remains poorly controlled. This relates to multiple factors including low antihypertensive efficacy of single drug therapies reluctance of primary care physicians to modify/titrate initially chosen therapy to obtain target blood pressure, and poor compliance with medication. Several guidelines for the treatment of high blood pressure now include combination therapy with low doses of 2 drugs as one of the strategies for the initial management of mild/moderate arterial hypertension. Evidence discussed in this article points to superior control of blood pressure by combinations of low doses of 2 drugs as compared with monotherapy in regular doses. This superior effectiveness of combined therapy relates to a better antihypertensive efficacy and higher response rates in the low range of doses as the result of complementary mechanisms of antihypertensive effects, better tolerance as a result of a lower rate of adverse effects in the low dose range, improved compliance from better tolerance and simple drug regimen, and lower cost. Whether increased use of fixed low dose combination therapies would translate to better control of arterial hypertension in the population and thereby further reduction of cardiovascular/cerebrovascular morbidity and mortality caused by hypertension remains to be assessed.

Direct vasodilators and their role in hypertension management: minoxidil

Minoxidil is a direct vasodilator that has been in use for over two decades. It is used primarily to reduce blood pressure in hypertensives who have been poorly controlled on various multidrug regimens. Although minoxidil is extremely effective, its usefulness is limited by its tendency to increase the pulse rate and to trigger salt and water retention. The latter may be incapacitating in some patients. Therefore, minoxidil is typically administered with both a diuretic and an agent that can control the pulse rate, such as a beta blocker. Minoxidil has several other side effects that may limit its use, including hypertrichosis, aggravation of myocardial ischemia and/or left ventricular hypertrophy, and (infrequently) pericardial effusions. If a patient's hypertensive pattern is sufficiently severe to warrant contemplation of minoxidil therapy, referring the patient to a hypertension specialist should be strongly considered. (c) 2001 by LeJacq Communications, Inc.

Mortality after coronary artery occlusion in different models of cardiac hypertrophy in rats

Chronic treatment with minoxidil induces cardiac trophic and sympathetic responses, which may increase the propensity for lethal arrhythmias. To test this hypothesis, acute coronary artery occlusion was performed in conscious normotensive rats treated for 2 or 5 weeks with minoxidil with the use of a 2-stage approach to cause a myocardial infarction. For comparison, rats with aortocaval (A-V) shunts and spontaneously hypertensive rats (SHR) were studied. Minoxidil increased left ventricular and right ventricular weights by 15% to 20%, and the A-V shunt increased these weights by 30% to 40%. In SHR, left ventricular weight was increased by 50%, and right ventricular weight was increased by 25%. In rats treated with minoxidil for 5 weeks, coronary artery occlusion caused a rapid and marked mortality, and 4 hours after myocardial infarction, only 18% of these rats were alive versus 61% of the control rats. In rats with the A-V shunt, coronary artery occlusion was also associated with increased mortality, and after 6 hours, 33% were still alive compared with 59% of the control rats. In contrast, SHR with marked hypertension and cardiac hypertrophy showed only a minor increase in mortality (survival rates were 53% versus 60% in SHR versus Wistar-Kyoto rats, respectively). Mortality was preceded by high arrhythmia scores, and ventricular fibrillation was the cause of death. Discontinuation of minoxidil for 1 week, sympathetic blockade with nadolol or clonidine, or blockade of the renin-angiotensin system with enalapril or losartan did not improve minoxidil-induced excess mortality. We conclude that ventricular stretch and other mechanisms (eg, cardiac vagal activity) in rats appear to be more potent than hypertension-induced left ventricular hypertrophy in predisposing for lethal arrhythmias in the setting of acute ischemia.

Synthesis of E- and Z-pyrazolylacrylonitriles and their evaluation as novel antioxidants

A facile synthesis of (Z)- and (E)-2-(5-arylpyrazol-3-yl)-3-(pyrrol-2-yl)acrylonitriles and (Z)-2-(1,3-diarylpyrazol-5-yl)-3-pyrrol-2-yl)acrylonitriles, and isomerisation of (Z)-2-(5-arylpyrazolyl)acrylonitriles to (E)-2-(5-arylpyrazolyl)acrylonitriles under basic conditions have been reported. (Z)-2-(1,3-Diarylpyrazolyl)acrylonitriles did not undergo isomerisation under the similar conditions. New compounds were identified on the basis of their spectral data (1H-, 13C-, 1H-1H COSY, NOESY, NOE, HMQC NMR, IR, UV and EI mass). The structures of one acrylonitrile and five of their precursor 6-arylpyran-2-ones and cyanomnethylpyrazoles were confirmed by X-ray crystallographic studies. Effects of pyrazolylacrylonitriles and their precursors on rat liver-microsomal lipid peroxidation were evaluated in vitro with a view to establish structure activity relationship and to identify a lead compound.

Relation of hemodynamic volume load to arterial and cardiac size

OBJECTIVES

This study sought to assess the relation of Doppler stroke volume (SV) to cardiac and carotid artery size and to determine whether volume load accounts for the parallelism between the two.

BACKGROUND

It has been suggested that altered hemodynamic volume load can modify the degree and pattern of left ventricular (LV) hypertrophy from that predicted from blood pressure (BP) alone.

METHODS

We related Doppler echocardiographic SV in 342 normotensive or unmedicated asymptomatic hypertensive adults to echocardiographic LV mass, LV internal dimension (LVID), wall thickness, carotid ultrasound arterial lumen diameter, intimal-medial thickness (IMT) and cross-sectional area (CSA).

RESULTS

SV was positively related to LV mass (r = 0.42), LVID (r = 0.45), ventricular wall thickness (r = 0.20 to 0.29) and carotid diameter (r = 0.23, all p < 0.0001); CSA (r = 0.17, p < 0.002); and IMT (r = 0.12, p = 0.03). In multivariate analyses controlling for awake ambulatory BP and the circumferential end-systolic stress/end-systolic volume index ratio, SV remained an independent predictor of LV mass and chamber size (both p < 0.0001) but not LV wall thickness. SV also predicted carotid diameter (p < 0.0002), CSA (p = 0.001) and, to a lesser degree, IMT (p = 0.02) after controlling for mean awake BP and age. In additional analyses, LV and carotid dimensions were significantly interrelated independent of SV.

CONCLUSIONS

SV measured by invasively validated Doppler echocardiography is associated with LV and carotid artery enlargement and eccentric hypertrophy, independent of arterial pressure, LV contractility, age and body size; however, SV and other variables do not account for the previously documented parallelism between cardiac and arterial structure.

Protection against cytosine arabinoside-induced alopecia by minoxidil in a rat animal model

BACKGROUND

Alopecia is one of the most physically and psychologically distressing side effect of cancer chemotherapeutic agents. In the past 2 years, we reported that: (a) treatment of 8-day-old rats with 1-B-D-arabinofuranosylcytosine (Ara-C), doxorubicin, and cyclophosphamide (CYC) consistently produced alopecia; (b) Imuvert, a biological response modifier, produced complete protection against alopecia induced by Ara-C and doxorubicin, but not that produced by CYC, most probably through the release of interleukin-1; and (c) n-acetylcysteine protected against CYC-induced alopecia in the newborn rat.

METHODS

As an extension to these observations, we chose to test the efficacy of minoxidil, a drug known to be a hypertrichotic agent, in preventing chemotherapy-induced alopecia in the newborn rat animal model.

RESULTS

Minoxidil, when injected locally, offered good local prevention against Ara-C but not CYC-induced alopecia. Minoxidil 2% dissolved in a vehicle of ethanol, propylene glycol, and water was not effective when applied topically.

CONCLUSIONS

The mechanism of action of minoxidil in its prevention against Ara-C-induced alopecia is currently unknown. This observation may shed some light on the in vivo mechanism of action of minoxidil and may prove to be important in our efforts to search for agents to prevent alopecia among patients receiving chemotherapy.

Potassium channel openers: pharmacological and clinical aspects

Opening of plasmalemmal K+ channels leads to cellular hyperpolarization which, in excitable tissues possessing voltage-dependent Ca2+ channels, prevents the opening of such channels and thus prevents excitation. In the last few years, an increasing number of compounds have been identified which elicit their effects by opening K+ channels, preferentially in smooth muscle, but also in other excitable tissues. These include the novel benzpyrans, cromakalim and bimakalim, the thioformamide aprikalim, and also well known antihypertensives such as minoxidil sulphate, diazoxide and pinacidil. After a short overview of the various families of K+ channel openers (KCOs), their basic pharmacological properties, including inhibition by the sulfonyl ureas (such as glibenclamide) are presented. The actual discussion concerning the type of K+ channel(s) opened by these compounds and their mechanism(s) of vasorelaxation will be reported. The therapeutic potential of these compounds in the cardiovascular field (as antihypertensives and, in particular, as anti-ischemic agents in heart and skeletal muscle), and in asthma (where they reverse established airway hyperreactivity) will also be discussed. Improved tissue selectivity may be the essential pre-requisite for true clinical success of this class of compounds.