Ephedrine was once widely used as a topical decongestant and as a bronchodilator in the treatment for asthma. It continues to be used for these indications, although its popularity is waning due to the availability of more effective agents for these indications which exhibit fewer adverse effects. The role in nasal congestion has largely been replaced by more potent α-adrenergic receptor agonists (e.g. oxymetazoline). Similarly the role of ephedrine in asthma has been almost entirely replaced by β2-adrenergic receptor agonists (e.g. salbutamol). Ephedrine continues to be used intravenously in the reversal of hypotension from spinal/epidural anaesthesia. It is also used in other hypotensive states, including overdose with ganglionic blocking agents, antiadrenergic agents, or other medications that lower blood pressure. It can be used in narcolepsy and nocturnal enuresis.
In traditional Chinese medicine, ephedrine has been used in the treatment of asthma and bronchitis for centuries.
An ECA stack is a component found in thermogenic weight loss pills, composed of ephedrine, caffeine and aspirin working to speed up the metabolism and thus cause food energy to burn faster. The ECA stack is a popular supplement taken by body builders before workouts due to the increased amount of energy and alertness.
For many years, the US Coast Guard recommended ephedrine together with an equal 25 mg dose of promethazine to its sailors to combat seasickness. Promethazine manages nausea and ephedrine fights the ensuing drowsiness. Commonly referred to as the Coast Guard cocktail, ephedrine may still be available for prescription for this purpose.
Adverse effects
Adverse drug reactions (ADRs) are more common with systemic administration (e.g. injection or oral administration) compared to topical administration (e.g. nasal instillations). ADRs associated with ephedrine therapy include:
- Cardiovascular: tachycardia, cardiac arrhythmias, angina pain, vasoconstriction with hypertension
- Dermatological: flushing, sweating, acne vulgaris
- Gastrointestinal: nausea, appetite loss, anorexia
- Genitourinary: increased urine output due to increased blood flow
- Nervous system: restlessness, confusion, insomnia, mild euphoria, mania/hallucinations (rare except in previously existing psychiatric conditions), delusions, formication (may be possible, but lacks documented evidence) paranoia, hostility, confusion, panic, stereotypical behaviour ('obsessive compulsive' or repetitive tasks such as cleaning, grooming, organizing items arbitrarily) agitation
- Respiratory: dyspnea, pulmonary edema
- Miscellaneous: dizziness, headache, tremor, hyperglycemic reactions
The reverse reaction, hydrolysis of the
resulting ester back to ethanol and the
carboxylic acid, limits the extent of
reaction, and high yields are unusual unless
water can be removed from the reaction
mixture as it is formed. Esterification can
also be carried out using more a reactive
derivative of the carboxylic acid, such as
an acyl chloride or acid anhydride.
The approved maximum daily dosage of ephedrine for use as a bronchodilator is 150mg, as specified on the packaging of the bronchodilator and expectorant combination, Bronkaid, made by Bayer pharmaceuticals.
Overdose can lead to death, although the approved dose is not likely to cause severe reactions when used as directed.
Ephedrine can also lead to damage of the brain receptors over a period of large usage this is because of its constant action on the neurochemicals. It also leads to high increase in blood pressure which over time can lead to damage in the blood vessels.
Contraindications
Ephedrine should not be used in conjunction with certain antidepressants, namely SNRIs (Selective norepinephrine re-uptake inhibitors), as this increases the risk of the above symptoms due to excessive serum levels of norepinephrine.
Wellbutrin is an example of an antidepressant with an amphetamine-like structure similar to ephedrine. It has a similar action but also releases serotonin from presynaptic clefts. It should not be used with ephedrine as it may increase the liklihood of the above side effects.
Ephedrine should be used in caution in patients with inadequate fluid replacement, impaired adrenal function, hypoxia, hypercapnia, acidosis, hypertension, hyperthyroidism, prostatic hypertrophy, diabetes mellitus, cardiovascular disease, during delivery if maternal BP > 130/80 mmHg, and lactation.
Contraindications for the use of ephedrine include: closed angle glaucoma, phaeochromocytoma, asymmetric septal hypertrophy (idiopathic hypertrophic subaortic stenosis), concomitant or recent (previous 14 days) monoamine oxidase inhibitor (MAOI) therapy, general anaesthesia with halogenated hydrocarbons (particularly cyclopropane or halothane), tachyarrhythmias or ventricular fibrillation, hypersensitivity to ephedrine or other stimulants. Ephedrine should NOT be used at any time during pregnancy unless specifically indicated by a qualified physician and ONLY when other options are unavailable.
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