Ephedrine has mixed actions
Natural ephedra plant. It can also be synthesized synthetically.
Mechanism of Action
Stimulates both alpha and beta receptors, but less stronger than adrenaline.
It acts in a mixed manner, stimulating either directly or indirectly by stimulating release of noradrenaline.
It also shows tachyphylaxis.
Non catecholamine given orally. It is non polar and crosses blood brain barrier. It is excreted unchanged in the urine.
- Increases heart contraction
- Increases heart rate (less than adrenaline)
- Increases systolic as well as diastolic blood pressure
- Increases cardiac output
- Causes bronchodilatation due to beta 2 effect.
- Causes decongestion because of vasoconstriction of respiratory mucosa (alpha 1 effect)
As it is a non catecholamine, it crosses the blood brain barrier and stimulates CNS directly. It produces alertness, euphoria, insomnia, this action is milder than amphetamines.
Ephedrine has fallen out of favour these days. It was used in
- Bronchial asthma
- Nasal decongestion (pseudo ephedrine used even now)
- Can be used even now for Spinal Anesthesia. When lignocaine etc. are injected in between the L2 and L3 segment in the spinal canal for producing paralysis below the umbilicus, sometimes the local anesthetic spreads leading to progressive paralyzation of sympathetic trunk. As a result severe hypotension might develop. This can be countered by ephedrine, which has a longer duration of action
Insomnia, restlessness, irritability, anxiety
Tachycardia, palpitations, hypertension, precipitation of angina pectoris
Because of alpha effect, contractions of smooth muscles of prostate and trigone might occur in older males, resulting in urinary retention.