Minoxidil and the treatment of severe hypertension

Efficacy of topical minoxidil in enhancing beard growth in a group of transgender assigned female at birth individuals on gender affirming hormone therapy

PURPOSE

Testosterone therapy represents the cornerstone of gender affirming hormone therapy (GAHT) among t-AFAB (transgender Assigned Female At Birth) people. Minoxidil is a vasodilator drug approved for topical use for the treatment of androgenetic alopecia. The aim of the present study was to evaluate the efficacy of topical minoxidil in enhancing beard growth in a group of t-AFAB people on GAHT.

METHODS

Sixteen t-AFAB individuals with an incomplete beard development, on GAHT for at least 6 months, were enrolled. Topical minoxidil was applied to the interested facial areas. Before starting (T0), after 3 (T3) and 6 (T6) months, we evaluated facial hair growth using the Ferriman-Gallwey modified score (FGm).

RESULTS

Subjects were 26 (2.7) years old and on GAHT for 18.5 [15-54] months; using a paired match evaluation, a statistically significant facial hair growth was observed over time, in particular at T6 (median upper lip FGm 3.5 [3-4] vs 2 [1-2] at T0 and chin FGm 4 [3.25-4] vs 1 [1-2] at T0; p ≤ 0.002). Comparing the minoxidil group with a control group (n = 16) matched for age and BMI who developed a full-grown beard only with GAHT, a logistic multivariable analysis identified hirsutism before GAHT was independently positively associated with the development of a full beard [OR 15.22 (95% CI 1.46-158.82); p = 0.023].

CONCLUSIONS

This is the first study demonstrating the efficacy of topical minoxidil in enhancing facial hair growth among t-AFAB people on GAHT. Further studies will be necessary to assess whether the obtained improvements will persist after discontinuing the medication.

Minoxidil Poisoning: A Case of Refractory Shock with Remarkable ECG Changes

How to cite this article: Dash S, Sashindran VK. Minoxidil Poisoning: A Case of Refractory Shock with Remarkable ECG Changes. Indian J Crit Care Med 2023;27(9):688-689.

Case Report: Successful Use of Minoxidil to Promote Facial Hair Growth in an Adolescent Transgender Male

Increasing numbers of trans and gender diverse young people are presenting to health services seeking gender-affirming medical care. While testosterone therapy in transgender males is generally effective in inducing masculinization, some adolescents encounter barriers to accessing such treatment or may not wish to experience all the changes that usually accompany testosterone. Here, we describe the case of a 17 year old trans male who presented with gender dysphoria but was initially unable to start testosterone therapy. Due to a desire for facial hair, he was therefore treated with topical minoxidil, an easily accessible, over-the-counter medication that has been used to treat androgenic alopecia for several decades. In this case, minoxidil was applied regularly to the lower face and, after three months of treatment, he developed obvious pigmented facial hair that was sufficient to help him avoid being misgendered. The only reported side effect was excessive skin dryness. Unexpectedly, despite no direct application to other areas, there was also an increase in pigmented body hair, suggestive of systemic absorption and effect. Given its long-standing use and safety record in the management of alopecia, minoxidil might thus represent a useful treatment option for trans males who desire an increase in facial hair.

α 2-Adrenoceptors: Challenges and Opportunities-Enlightenment from the Kidney

It was indeed a Don Quixote-like pursuit of the mechanism of essential hypertension when we serendipitously discovered α₂-adrenoceptors (α₂-ARs) in skin-lightening experiments in the frog. Now α₂-ARs lurk on the horizon involving hypertension causality, renal denervation for hypertension, injury from falling in the elderly and prazosin's mechanism of action in anxiety states such as posttraumatic stress disorder (PTSD). Our goal here is to focus on this horizon and bring into clear view the role of α₂-AR-mediated mechanisms in these seemingly unrelated conditions. Our narrative begins with an explanation of how experiments in isolated perfused kidneys led to the discovery of a sodium-retaining process, a fundamental mechanism of hypertension, mediated by α₂-ARs. In this model system and in the setting of furosemide-induced sodium excretion, α₂-AR activation inhibited adenylate cyclase, suppressed cAMP formation, and caused sodium retention. Further investigations led to the realization that renal α₂-AR expression in hypertensive animals is elevated, thus supporting a key role for kidney α₂-ARs in the pathophysiology of essential hypertension. Subsequent studies clarified the molecular pathways by which α₂-ARs activate prohypertensive biochemical systems. While investigating the role of α₁-adrenoceptors (α₁-ARs) versus α₂-ARs in renal sympathetic neurotransmission, we noted an astonishing result: in the kidney α₁-ARs suppress the postjunctional expression of α₂-ARs. Here, we describe how this finding relates to a broader understanding of the role of α₂-ARs in diverse disease states. Because of the capacity for qualitative and quantitative monitoring of α₂-AR-induced regulatory mechanisms in the kidney, we looked to the kidney and found enlightenment.

Optimizing Antihypertensive Medication Classification in Electronic Health Record-Based Data: Classification System Development and Methodological Comparison

Background

Computable phenotypes have the ability to utilize data within the electronic health record (EHR) to identify patients with certain characteristics. Many computable phenotypes rely on multiple types of data within the EHR including prescription drug information. Hypertension (HTN)-related computable phenotypes are particularly dependent on the correct classification of antihypertensive prescription drug information, as well as corresponding diagnoses and blood pressure information.

Objective

This study aimed to create an antihypertensive drug classification system to be utilized with EHR-based data as part of HTN-related computable phenotypes.

Methods

We compared 4 different antihypertensive drug classification systems based off of 4 different methodologies and terminologies, including 3 RxNorm Concept Unique Identifier (RxCUI)–based classifications and 1 medication name–based classification. The RxCUI-based classifications utilized data from (1) the Drug Ontology, (2) the new Medication Reference Terminology, and (3) the Anatomical Therapeutic Chemical Classification System and DrugBank, whereas the medication name–based classification relied on antihypertensive drug names. Each classification system was applied to EHR-based prescription drug data from hypertensive patients in the OneFlorida Data Trust.

Results

There were 13,627 unique RxCUIs and 8025 unique medication names from the 13,879,046 prescriptions. We observed a broad overlap between the 4 methods, with 84.1% (691/822) to 95.3% (695/729) of terms overlapping pairwise between the different classification methods. Key differences arose from drug products with multiple dosage forms, drug products with an indication of benign prostatic hyperplasia, drug products that contain more than 1 ingredient (combination products), and terms within the classification systems corresponding to retired or obsolete RxCUIs.

Conclusions

In total, 2 antihypertensive drug classifications were constructed, one based on RxCUIs and one based on medication name, that can be used in future computable phenotypes that require antihypertensive drug classifications.

Hypertension Drug Therapy

Hypertension is still the number one global killer. No matter what causes are, lowering blood pressure can significantly reduce cardiovascular complications, cardiovascular death, and total death. Unfortunately, some hypertensive individuals simply do not know having hypertension. Some knew it but either not being treated or treated but blood pressure does not achieve goal. The reasons for inadequate control of blood pressure are many. One important reason is that we are not very familiar with antihypertensive agents and less attention has been paid to comorbidities, complications as well as the hypertension-modified target organ damage in patients with hypertension. The right antihypertensive drug was not given to the right hypertensive patients at right time. This reviewer studied comprehensively the literature, hopefully that the review will help improve antihypertensive drug selection and antihypertensive therapy.

Annurca Apple Nutraceutical Formulation Enhances Keratin Expression in a Human Model of Skin and Promotes Hair Growth and Tropism in a Randomized Clinical Trial

Several pharmaceutical products have been formulated over the past decades for the treatment of male and female alopecia, and pattern baldness, but relatively few metadata on their efficacy have been published. For these reasons, the pharmaceutical and medical attention has recently focused on the discovery of new and safer remedies. Particularly, great interest has been attracted by oligomeric procyanidin bioactivity, able to promote hair epithelial cell growth as well as to induce the anagen phase. Specifically, the procyanidin B2, a dimeric derivative extracted from apples, has demonstrated to be one of the most effective and safest natural compounds in promoting hair growth, both in vitro and in humans by topical applications. By evaluating the polyphenolic content of different apple varieties, we have recently found in the apple fruits of cv Annurca (AFA), native to Southern Italy, one of the highest contents of oligomeric procyanidins, and, specifically, of procyanidin B2. Thus, in the present work we explored the in vitro bioactivity of AFA polyphenolic extract as a nutraceutical formulation, named AppleMets (AMS), highlighting its effects on the cellular keratin expression in a human experimental model of adult skin. Successively, testing the effects of AMS on hair growth and tropism in healthy subjects, we observed significant results in terms of increased hair growth, density, and keratin content, already after 2 months. This study proves for the first time the impact of apple procyanidin B2 on keratin biosynthesis in vitro, and highlights its effect as a nutraceutical on human hair growth and tropism.

Hypertension's 3 Dilemmas and 3 Solutions: Pharmacology of the Kidney in Hypertension

The Hypertension Community has 3 conflicting dilemmas: a goal systolic pressure of 120 mm Hg or less (the SPRINT Trials), 40% of our 60,000,000 hypertensives still sustain blood pressures above 140/90 mm Hg, and our most potent antihypertensive drug minoxidil sits on the sidelines, imprisoned in the Food and Drug Administration's Black Box designation. My solutions to these dilemmas are: (1) review of the facts of our most potent antihypertensive drug minoxidil which is essentially free of toxicity, (2) treatment focus on the fundamental cause of high blood pressure, that is excess dietary sodium and, (3) prevention of, and/or reversal of, the fundamental mechanism of worsening hypertension, arteriolar hypertrophy.

SUMMARY

The Hypertension Community has 3 conflicting dilemmas: a goal systolic pressure of 120 mm Hg or less (the SPRINT Trials), 40% of our 60,000,000 hypertensives still sustain blood pressures above 140/90 mm Hg, and our most potent antihypertensive drug minoxidil sits on the sidelines, imprisoned in the Food and Drug Administration's Black Box designation. My solutions to these dilemmas are: (1) review of the facts of our most potent antihypertensive drug minoxidil which is essentially free of toxicity, (2) treatment focus on the fundamental cause of high blood pressure (HBP) and excess dietary sodium and, (3) prevention of, and/or reversal of, the fundamental mechanism of worsening hypertension, arteriolar hypertrophy. My focus at UT Southwestern in Dallas was on extremely severely hypertensive patients with a quantifiable, measurable complication of HBP, progression of nephrosclerotic damage to kidneys. This model had the greatest likelihood of exposing fundamental disregulatory mechanisms in hypertensive patients (which it did) and the potential for study of the most relevant antihypertensive drug interactions to achieve optimal blood pressure control (which it did). By maintaining diastolic pressures at 80 mm Hg or less in the first National Institutes of Health-supported, long-term randomized clinical trial to save the kidneys, the bases for a fundamental blood pressure support mechanism (arteriolar hypertrophy) was illuminated but not fully described until now. This fundamental hypertensinogenic mechanism results from HBP but with time and severity, becomes its own raison d'être. I am now aged 84 years. As a result of a stroke 20 years ago, which caused permanent double vision, and because of poor blood pressure control with triple therapy, I started using minoxidil 5 mg/d along with atenolol and occasional furosemide. Now, along with some dietary salt restriction, my resting blood pressure is 110/65-125/75 and, despite >30 years history of HBP, I have no retinal arteriolar hypertrophy nor arcus senilis (Dr. Schwartz-U. of Miami) which is almost universally present at this age. Yes, prevention of, or reversal of, arteriolar hypertrophy should be a central focus of HBP treatment. I simply wish to share a bit of accumulated wisdom that might be of use to others.

Elastomeric free-form blood vessels for interconnecting organs on chip systems

Conventional blood vessel-on-a-chip models are typically based on microchannel-like structures enclosed within bulk elastomers such as polydimethylsiloxane (PDMS). However, these bulk vascular models largely function as individual platforms and exhibit limited flexibility particularly when used in conjunction with other organ modules. Oftentimes, lengthy connectors and/or tubes are still needed to interface multiple chips, resulting in a large waste volume counterintuitive to the miniaturized nature of organs-on-chips. In this work, we report the development of a novel form of a vascular module based on PDMS hollow tubes, which closely emulates the morphology and properties of human blood vessels to integrate multiple organs-on-chips. Specifically, we present two templating strategies to fabricate hollow PDMS tubes with adjustable diameters and wall thicknesses, where metal rods or airflow were employed as the inner templates, while plastic tubes were used as the outer template. The PDMS tubes could then be functionalized by human umbilical vein endothelial cells (HUVECs) in their interior surfaces to further construct elastomeric biomimetic blood vessels. The endothelium developed biofunctionality as demonstrated by the expression of an endothelial biomarker (CD31) as well as dose-dependent responses in the secretion of von Willebrand factor and nitric oxide upon treatment with pharmaceutical compounds. We believe that with their clear advantages including high optical transparency, gas permeability, and tunable elasticity matching those of native blood vessels, these free-form PDMS vascular modules can supplement bulk vascular organoids and likely replace inert plastic tubes in integrating multiple organoids into a single microfluidic circuitry.

Minoxidil-associated anorexia in an infant with refractory hypertension

Minoxidil is a potent antihypertensive used as an adjunctive agent in refractory hypertension. It exerts an antihypertensive effect through two mechanisms: selective arterial vasodilation by activation of potassium channels in the vascular smooth muscle and stimulation of carotid and aortic baroreceptors, leading to downstream release of renin and norepinephrine. Although frequently cited in reviews of antihypertensive agents, limited data about the use of minoxidil in neonates are available. We describe an infant girl, born at 35 weeks of gestation, who was diagnosed with idiopathic hypertension after extensive diagnostic evaluation. Adequate blood pressure control was not achieved with captopril, amlodipine, and clonidine. Oliguria secondary to captopril and rapid-onset congestive heart failure due to persistent hypertension led to the introduction of intravenous agents labetalol and nitroprusside. Although adequate blood pressure control was achieved, attempts to transition back to oral agents were unsuccessful, prompting the use of minoxidil as an alternative agent. Although good blood pressure control was achieved, the infant's oral intake plummeted from 210 to 63 ml/kg/day. The anorexia quickly resolved after stopping minoxidil, and she was discharged home at 5 months of age receiving propranolol, amlodipine, and doxazosin. Use of the Naranjo adverse drug reaction probability scale indicated a definite relationship (score of 10) between the patient's development of anorexia and minoxidil therapy. To our knowledge, there have been no previous reports of minoxidil-associated anorexia in preterm or term infants. Clinicians should be aware that anorexia is a possible adverse effect of minoxidil in this patient population when initiating the drug in similar patients.

Regenerative medicine and hair loss: how hair follicle culture has advanced our understanding of treatment options for androgenetic alopecia

Many of the current drug therapies for androgenetic alopecia were discovered serendipitously, with hair growth observed as an off-target effect when drugs were used to treat a different disorder. Subsequently, several studies using cultured cells have enabled identification of hair growth modulators with similar properties to the currently available drugs, which may also provide clinical benefit. In situations where the current therapeutics do not work, follicular unit transplantation is an alternative surgical option. More recently, the concept of follicular cell implantation, or hair follicle neogenesis, has been attempted, exploiting the inherent properties of cultured hair follicle cells to induce de novo hair growth in balding scalp. In this review, we discuss both the advances in cell culture techniques that have led to a wider range of potential therapeutics to promote hair growth, in addition to detailing current knowledge on follicular cell implantation, and the challenges in making this approach a reality.

FGF5 is a crucial regulator of hair length in humans

Mechanisms that regulate the growth of eyelashes have remained obscure. We ascertained two families from Pakistan who presented with familial trichomegaly, or extreme eyelash growth. Using a combination of whole exome sequencing and homozygosity mapping, we identified distinct pathogenic mutations within fibroblast growth factor 5 (FGF5) that underlie the disorder. Subsequent sequencing of this gene in several additional trichomegaly families identified an additional mutation in FGF5. We further demonstrated that hair fibers from forearms of these patients were significantly longer than hairs from control individuals, with an increased proportion in the growth phase, anagen. Using hair follicle organ cultures, we show that FGF5 induces regression of the human hair follicle. We have identified FGF5 as a crucial regulator of hair growth in humans for the first time, to our knowledge, and uncovered a therapeutic target to selectively regulate eyelash growth.

Sulfation of minoxidil by multiple human cytosolic sulfotransferases

Minoxidil is an antihypertensive agent and hair growth promoter that is metabolized by sulfation to the active compound, minoxidil sulfate. Thermostable phenol sulfotransferase (TS PST or P-PST) was initially thought to catalyze the reaction, and the enzyme was designated minoxidil sulfotransferase (MNX-ST). Information about human ST activities toward minoxidil would be useful in developing the capacity to predict individual responses to minoxidil based on tissue levels of STs. Therefore, human STs were studied from platelet homogenates, partially purified platelets, scalp skin high speed supernatants and COS-1 cell cDNA expressed preparations using a radiochemical enzymatic assay with minoxidil as the substrate. Studies showed the presence of TS PST, TL (thermolabile) PST and MNX-ST activities in human scalp skin. Biochemical properties and correlation studies suggested that in addition to TS PST, the TL PST activity, another ST activity or both were involved in the reaction. Partially purified human platelet TL PST tested with minoxidil and dopamine showed identical thermal stabilities and similar responses to the inhibitors 2,6-dichloro-4-nitrophenol (DCNP) and NaCl. To characterize the activity of TL PST toward minoxidil, several biochemical properties of the enzyme expressed from a human liver cDNA clone were investigated. When assayed with minoxidil and dopamine, thermal stabilities of the expressed enzyme were identical and IC50 values for the inhibitors DCNP and NaCl were similar. It was also demonstrated that cDNA encoded human liver dehydroepiandrosterone sulfotransferase and estrogen sulfotransferase contributed to the sulfation of minoxidil. The results confirm that at least four human STs contribute to minoxidil sulfation. MNX-ST activity represents a combination of ST activities. The data indicate that multiple ST activities should be taken into account in attempts to predict the regulation of minoxidil sulfation and individual responses to minoxidil.

Characterization of recombinant human liver dehydroepiandrosterone sulfotransferase with minoxidil as the substrate

Biotransformation of xenobiotics and hormones through sulfate conjugation is an important metabolic pathway in humans. The activation of minoxidil, an antihypertensive agent and hair growth stimulator, by sulfation (sulfonation) is carried out by more than one sulfotransferase. Initially only the thermostable form of phenol sulfotransferase was thought to catalyze minoxidil sulfation. We document in this report the new finding that human liver dehydroepiandrosterone sulfotransferase (DHEAST), an hydroxysteroid sulfotransferase distinct from phenol sulfotransferases, also catalyzes the reaction. To characterize more precisely the activity of DHEA ST toward minoxidil, we used COS-1 cells to express DHEA ST from a human liver cDNA clone. The apparent Km values for minoxidil and [35S]3'-phosphoadenosine-5'-phosphosulfate were 3.9 mM and 0.13 microM, respectively. The 50% inactivation temperature of the COS-expressed enzyme was 42 degrees, and the IC50 value for 2,6-dichloro-4-nitrophenol was 1.4 x 10(-4) M. Both the thermal stability behavior and response to DCNP were similar when the cDNA encoded DHEA ST was assayed with DHEA or minoxidil as a substrate. NaCl led to a greater activation of the cDNA expressed DHEA ST when assayed with DHEA (2.5-fold) than when the same preparation was assayed with minoxidil (1.4-fold). These data indicate that DHEA ST catalyzes the sulfate conjugation of minoxidil: DHEA ST activity present in the human gut and liver would be expected to add to the overall sulfate conjugation of orally administered minoxidil. Thus, DHEA ST activity must be considered when determining the human tissue sulfotransferase contribution to minoxidil sulfation.

Angiotensin II causes weight loss and decreases circulating insulin-like growth factor I in rats through a pressor-independent mechanism

The renin-angiotensin system regulates normal cardiovascular homeostasis and is activated in certain forms of hypertension and in heart failure. Angiotensin II has multiple physiological effects and we have shown recently that its growth-promoting effects on vascular smooth muscle require autocrine activation of the IGF I receptor. To study the effect of angiotensin II on circulating IGF I, we infused rats with 500 ng/kg/min angiotensin II for up to 14 d. Angiotensin II markedly reduced plasma IGF I levels (56 and 41% decrease at 1 and 2 wk, respectively) and IGF binding protein-3 levels, and increased IGF binding protein-2 levels, a pattern suggestive of dietary restriction. Compared with sham, angiotensin II-infused hypertensive rats lost 18-26% of body weight by 1 wk, and pair-feeding experiments indicated that 74% of this loss was attributable to a reduction in food intake. The vasodilator hydralazine and the AT1 receptor antagonist losartan had comparable effects to reverse angiotensin II-induced hypertension, but only losartan blocked the changes in body weight and in circulating IGF I and its binding proteins produced by angiotensin II. Moreover, in Dahl rats that were hypertensive in response to a high-salt diet, none of these changes occurred. Thus, angiotensin II produces weight loss through a pressor-independent mechanism that includes a marked anorexigenic effect and an additional (likely metabolic) effect. These findings have profound implications for understanding the pathophysiology of conditions, such as congestive heart failure, in which the renin-angiotensin system is activated.

Hyperfiltration and conservation of renal function in hypertensive nephrosclerosis patients

Renal glomerular hyperfiltration has been proposed as an important contributing factor to the progression of hypertensive nephrosclerosis in rats with reduced renal mass. However, no clinical studies have assessed the role of glomerular hyperfiltration in the pathogenesis of hypertensive nephrosclerosis in humans. In a prospective, randomized, long-term blood pressure control study with up to 3 years follow-up, we showed that good blood pressure control with a mean diastolic blood pressure < or = 95 mm Hg preceded by a 2- to 4-month period of diastolic blood pressure < or = 80 mm Hg improved renal function in hypertensive nephrosclerosis patients. Patients treated with minoxidil, an angiotensin-converting enzyme inhibitor (enalapril), or a calcium entry blocker (nifedipine) had improvement in renal function, as indicated by a positive slope of the reciprocal serum-creatine concentration versus time and an increment in glomerular filtration rate. These results suggested that improvement in renal function occurred with these major types of antihypertensive drug treatment. To assess the renal hemodynamics of minoxidil, enalapril, and nifedipine, eight patients with hypertensive nephrosclerosis were admitted to the General Clinical Research Center for renal clearance studies on each drug while ingesting a fixed-calorie, 12% protein, 40% fat, and 100 mEq Na/d diet. Mean blood pressure, effective renal plasma flow, and renal vascular resistance did not change during the three phases of treatment. However, minoxidil treatment increased the glomerular filtration rate by 48% versus enalapril and by 79% versus nifedipine. Since minoxidil treatment improves renal function while causing a relative hyperfiltration, glomerular hyperfiltration per se is an unlikely mechanism for the progression of hypertensive nephrosclerosis in humans.

Simultaneous two-probe laser Doppler velocimetric assessment of topically applied drugs in rats

A simple, noninvasive method for the determination of cutaneous blood flow in anesthetized rats is presented. Simultaneous two-probe laser doppler velocimetry is shown to be a useful preclinical tool for the assessment of topically applied drugs.

Pruritic rash with actinic keratosis and impending exfoliation in a patient with hypertension managed with minoxidil

Dermatological toxicity has been reported following initiation of therapy with minoxidil, but no cases have been reported following prolonged use. We report the emergence of an erythematous weeping rash with impending exfoliation three years after the initiation of minoxidil therapy. Minoxidil was withdrawn and the patient responded to therapy with topical corticosteroids. Following minor surgery, the patient was inadvertently rechallenged with minoxidil. Within 24 hours of exposure bullous lesions reappeared in the extremities which again resolved with topical corticosteroids. Dermatological lesions observed on this patient were similar to those reported following acute minoxidil exposure and strongly implicate chronic minoxidil therapy.

Action of topical minoxidil in the bald stump-tailed macaque

The effect of topical minoxidil (5% and 2% solutions) on hair regrowth was studied in the frontal bald scalp of 18 adolescent and adult stump-tailed macaques (Macaca arctoides). Gross observation of the hairiness and folliculogram analysis of the skin biopsy specimens have shown that minoxidil induces the enlargement of vellus follicles to the size of middle to terminal follicles (regrowth of hair effect), minoxidil maintains the terminal follicles in the prebald scalp of periadolescent animals (prevention of baldness effect), enlarged follicles regress after minoxidil is withdrawn, and hair follicular growth is once again stimulated when treatment with minoxidil is reinstituted. Hair regrowth was more prominent in the early stage of baldness among younger macaques than in baldness of longer duration in older animals. An in vitro study of 3H thymidine uptake revealed that the hair follicles in minoxidil-treated macaque skin showed significant enhancement of deoxyribonucleic acid synthesis in the follicular and perifollicular cells but not in the epidermal keratinocytes. Furthermore, the uptake of 3H minoxidil and its conversion to minoxidil sulfate (the active metabolite producing vasodilation) was relatively higher in the hair follicles than in the epidermis and dermis. Serum concentration of minoxidil was fairly constant 2, 4, 6, 15, and 24 hours after a single application (averaging 15 ng/ml with 5% minoxidil). Minoxidil's essential action in hair follicular growth may be as a potent vasodilator. However, a direct action on the hair follicle cannot be ruled out considering uptake and conversion of the drug to minoxidil sulfate within the hair follicle itself.

Nifedipine in the management of hypertensive emergencies: report of two cases and review of the literature

Calcium channel blockers are assuming increasingly important roles in the practice of emergency medicine. Two cases and a review of the literature relating to treatment of hypertensive emergencies with nifedipine are presented. Nifedipine has a rapid onset of action (buccal, 10-15 minutes; oral, 30-45 minutes) and peak effect (buccal, 30 minutes, oral, 60 minutes). The duration of effects is four to six hours regardless of the route of administration, with a mean arterial pressure reduction of 21.6% (248/134 mm Hg to 165/87 mm Hg). In patients with severe hypertension and left ventricular failure, a consistent reduction in systemic vascular resistance (2,088 dynes/sec/cm-5 to 1242 dynes/sec/cm-5) and cardiac index (2.76 l/min/m2 to 3.77 l/min/m2) has been reported. The patients in this study had severe hypertension (systolic blood pressure greater than 180 mm Hg, diastolic blood pressure greater than 120 mm Hg) and end organ involvement (including heart failure, left ventricular strain, headache, confusion, dizziness, and shortness of breath). Nifedipine (10 mg) was administered buccally with prompt reduction of blood pressure and resolution of the patients' symptoms. Nifedipine appears to be a safe, effective agent for the management of hypertensive emergencies. Its pharmacokinetic profile and routes of administration make it particularly valuable in the practice of emergency medicine.

Sleep apnoea in a hypertensive population

50 hypertensive patients and 50 normal controls were evaluated in the sleep laboratory for the presence of sleep apnoea or sleep apnoeic activity. Hypertensive patients were at high risk of sleep apnoea; 15 hypertensive patients (30%) had sleep apnoea and another 17 (34%) had sleep apnoeic activity. In contrast, none of the age-matched and sex-matched control subjects had sleep apnoea, and 24% had sleep apnoeic activity. The degree of oxygen desaturation was correlated with the duration as well as the number of apnoeic events. Presence of sleep apnoea in the patients was significantly correlated with higher blood pressure levels when they were initially seen in the clinic. Patients with the most severe sleep apnoea had the highest initial blood-pressure levels and were more refractory to treatment.

Vasodilator therapy in chronic congestive heart failure

Vasodilator agents are relatively new additions to the armamentarium for the management of patients with congestive heart failure. Myocardial failure, irrespective of the aetiology, tends to create a vicious cycle characterised by reduced cardiac output and elevated systemic vascular resistance, which further decrease cardiac output by increasing left ventricular ejection impedance. The rationale for the use of vasodilators is to interrupt the vicious cycle by decreasing the left ventricular ejection impedance by peripheral vasodilatation. Although most vasodilator agents produce qualitatively similar haemodynamic responses, quantitatively their haemodynamic effects differ considerably. Knowledge of the haemodynamic effects of the various vasodilators helps in the selection of a particular drug for the management of such patients. This article reviews the mechanisms of action, haemodynamic effects, pharmacokinetics, clinical usage and adverse effects of non-parenteral vasodilator agents currently available for the management of patients with chronic heart failure.

Minoxidil in severe and moderately severe hypertension, in association with methyldopa and chlortalidone

Minoxidil is a potent antihypertensive drug widely used in severe arterial hypertension and in that refractory to treatment. Its effectiveness in less severe forms of hypertension was evaluated in 15 patients who had either a severe to moderate arterial hypertension not previously treated, or who did not tolerate the side effects of other antihypertensive drugs. The usefulness of methyldopa and chlortalidone to prevent a potential minoxidil-induced tachycardia and fluid retention, respectively, was also tested. The patients were initially treated with chlortalidone 100 mg/day, and methyldopa 500 mg/day. Minoxidil was then given in increasing doses until the diastolic blood pressure was equal to or inferior to 90 mmHg. This occurred consistently at doses which ranged from 5 to 50 mg/day (average, 29 mg). Treatment with minoxidil was continued for four months; tolerance to the drugs was not observed. Low doses of methyldopa and chlortalidone were effective in controlling the tachycardia and the retention of sodium and water induced by minoxidil. The three associated drugs were well tolerated and the life quality improved in most patients. Hypertrichosis was the most consistent side effect. Two patients were withdrawn from the study after the blood pressure was controlled by minoxidil, because of the appearance of angor in one, and edema and heart failure in the other.

The addition of prazosin to standard triple therapy in the treatment of severe hypertension

1 A small dose of prazosin was added to the treatment regime of sixteen hypertensive patients poorly controlled on a combination of bendrofluazide, hydralazine and propranolol. 2 There was a significant improvement in blood pressure control in all patients at 1 month (P less than 0.01) and this was maintained at 9 months (P less than 0.02). Tolerance to prazosin was not a problem. 3 The addition of prazosin to conventional triple drug therapy produces a further useful fall in blood pressure.