The use of epinephrine based eye-drops, commonly used to treat glaucoma, may also lead to a buildup of adrenochrome pigments in the conjunctiva, iris, lens, and retina. Rarely, exposure to medically administered epinephrine may cause Takotsubo cardiomyopathy.Use is contraindicated in people on nonselective β-blockers because severe hypertension and even cerebral hemorrhage may result. Mechanism of action
As a hormone, epinephrine acts on nearly all body tissues. Its actions vary by tissue type and tissue expression of adrenergic receptors. For example, high epinephrine levels cause smooth muscle relaxation in the airways but cause contraction of the smooth muscle that lines most arterioles.Epinephrine acts by binding to a variety of adrenergic receptors. Epinephrine is a nonselective agonist of all adrenergic receptors, including the major subtypes α1, α2, β1, β2, and β3. Epinephrines binding to these receptors triggers several metabolic changes. Binding to α-adrenergic receptors inhibits insulin secretion by the pancreas, stimulates glycogenolysis in the liver and muscle, and stimulates glycolysis and inhibits insulin-mediated glycogenesis in muscle. β adrenergic receptor binding triggers glucagon secretion in the pancreas, increased adrenocorticotropic hormone (ACTH) secretion by the pituitary gland, and increased lipolysis by adipose tissue. Together, these effects increase blood glucose and fatty acids, providing substrates for energy production within cells throughout the body. In the heart, the coronary arteries have a predominance of β2 receptors, which cause vasodilation of the coronary arteries in the presence of epinephrine.Its actions increase peripheral resistance via α1 receptor-dependent vasoconstriction and increase cardiac output via its binding to β1 receptors.
Focal seizures can be located only in the area of the brain responsible for the stimulus, spread to other areas of the brain, or even develop into a generalized seizure. Triggers
Stimuli that cause reflex seizures can be categorized as either intrinsic or extrinsic. For a given person, the stimulus that triggers may be intrinsic, extrinsic, or a combination of both. Extrinsic stimuli
Extrinsic stimuli are sensory stimuli that originate from the persons environment. Similar to intrinsic stimuli, extrinsic stimuli can be divided into two categories, either simple or complex. Examples of simple extrinsic stimuli include flashing lights or touch while complex extrinsic stimuli can include music, language, reading, or stimulation from eating. Some of the more common types of reflex epilepsy include light and music.Photosensitive epilepsy is an abnormal sensitivity of the brain to visual stimuli and is the most common trigger in reflex seizures. Reflex seizures can be induced by both flickering or non-flicking light, television, video games, or other visual patterns. Most people who have photosensitive epilepsy are sensitive to specific patterns for visual stimuli. Visual stimuli of a particular frequency (15-25  flashes/second), wavelength (red light at 660-720 nm), and at high contrast have been shown to have a higher risk of inducing seizures in people who are photosensitive. In addition, emotional excitement, fatigue, or length of exposure can all effect the risk of seizures.Musicogenic epilepsy is a rare reflex epilepsy that is thought to be an abnormal sensitivity of the brain to musical stimuli, however, the exact mechanism of these seizures is unknown.