Isoprenaline can produce tachycardia (an elevated heart rate), which predisposes people who take it to cardiac arrhythmias. Pharmacodynamics
Isoprenaline is a β1 and β2 adrenoreceptor agonist and has almost no activity on alpha adrenergic receptors. Its agonist effects at TAAR1 provide it with pharmacodynamic effects that resemble those of the endogenous trace amines, like tyramine.Isoprenalines effects on the cardiovascular system (non-selective) relate to its actions on cardiac β1 receptors and β2 receptors on smooth muscle within the tunica media of arterioles. Isoprenaline has positive inotropic and chronotropic effects on the heart. β2 adrenoceptor stimulation in arteriolar smooth muscle induces vasodilation. Its inotropic and chronotropic effects elevate systolic blood pressure, while its vasodilatory effects tend to lower diastolic blood pressure. The overall effect is to decrease mean arterial pressure due to the β2 receptors vasodilation.The isopropylamine group in isoprenaline makes it selective for β receptors. The free catechol hydroxyl groups keep it susceptible to enzymatic metabolism. Pharmacokinetics
The plasma half-life for isoprenaline is approximately two minutes. Chemistry
It is structurally related to epinephrine. History
It was first approved in the US in 1947. Between 1963 and 1968 in England, Wales, Scotland, Ireland, Australia, and New Zealand there was an increase in deaths among people using isoprenaline to treat asthma. This was attributed to overdose: the inhalers produced in that area were dispensing five times the dosage dispensed by inhalers produced in the US and Canada, where the deaths were not observed.
Signs and symptoms
Lesions of erythrasma are initially pink, but progress quickly to become brown and scaly (as skin starts to shed), which are sharply distinguished. Erythrasmic patches are typically found in moist and intertriginous areas (skin fold areas—e.g. armpit, groin, under breast) and can be well-defined patches or irregular. The most common is interdigital erythrasma, which is of the foot, and may present as a scaling, fissuring, and chronic non-resolving break down of the toe web interspaces. The slightly webbed spaces between toes, or other body region skin folds, make it difficult to distinguish from various Tinea. The patient is commonly otherwise asymptomatic. Cause
Erythrasma is caused by Corynebacterium minutissimum. This bacterium tends to thrive in mostly moist and warm environments. Great contributors are poor hygiene, obesity, hyperhidrosis (excessive sweating), aging, diabetes mellitus, and a poorly functioning immune system. Only some of the causable factors can be modified to reduce risk. Hygiene can be improved, along with avoiding moist and warm environments. Diagnosis
The differential diagnosis for erythrasma includes psoriasis, candidiasis, dermatophytosis, and intertrigo. The diagnosis can be made on the clinical picture alone. However, a simple side-room investigation with a Woods lamp is additionally useful in diagnosing erythrasma. The ultraviolet light of a Woods lamp causes the organism to fluoresce a characteristic coral red color, differentiating it from other skin conditions such as tinea versicolor, which may fluoresce a copper-orange color. Another route to differentiate erythrasma would be through bacterial and mycology related cultures to compare/contrast normal results to these findings. These are both non-invasive routes.