Ephedrine
Chemical
Indirect acting synthetic non-catecholamine
Use
Hypotension
Nasal decongestant (pseudoephedrine)
Presentation
(IV) clear, colourless solution 30mg/mL
(PO) 30mg tablets
Nasal drops 1%
Dose
(IV) 3 – 6mg aliquots
(Top) 1 – 2 drops nasally tds
(PO) 30mg tds
Route
PO / IM / IV / Topical
Onset
PO → 60 mins, lasts 3 – 5hrs
IV → immediate, lasts 1hr
DoA
MoA
Indirect: Enters adrenergic nerve terminals, displaces NA & promotes its release
Direct: Stimulation of α & β adrenergic receptors
PD
CVS
Similar CVS profile to adrenaline
Most effects due to β1 stimulation
+ INOTROPY, + CHRONOTROPY
↑CO
↑Myocardial work & myocardial O2 consumption
↑CBF, ↑SBP, ↑DBP
Note: less potent & longer DoA cf. adrenaline (due to no COMT/MAO metabolism)
RESP
Stimulant & bronchodilation
CNS
↑CBF
Mydriasis
Regional BF
↓RBF
↓GI BF
Metabolic
↑BSL
↑Glycogenolysis
PK
A
Well absorbed
D
Extensive, 122 – 320L; crosses placenta, present in breast milk
M
Some liver metabolism by N-demethylation
E
40% dose excreted, unchanged ∴impaired excretion with renal disease & ↑DoA
Adverse Effects
Dysrhythmia
Acute hypotensive crisis → especially with MAOI
Nausea & vomiting
Chest pain
Tachyphylaxis