Download 99A11 - Anaesthesia Online

Phenylephrine
Methoxamine
Ephedrine
Metaraminol
Intro
Direct acting
sympathomimetic amine
Use
Low SVR with spinals or
drug induced
-50-100mcg boluses
nasal decongestant
in cold and flu tabs
mydriatic
Direct acting
sympathomimetic amine
No longer in production
Low SVR
1mg
Naturally occurring
Indirect and direct acting
sympathomimetic amine
Hypotension with GA spinal
epidural
Nocturnal enuresis
Narcolepsy
Diabetic autonomic neuropathy
Hiccups and as nasal decongestant
Synthetic
Indirect and direct acting
sympathomimetic amine
Hypotension a/w spinal, epidural or
GA
0.5-2mg boluses
MOA
Potent A1 agonist. No B
effects
Potent A1 agonist. No B
effects
Indirect and direct
A1 but some B activity
Pharmaceut
ics
CCS
10mg/ml
CCS
20mg/ml
Direct stim A and B R
Indirect release of NA from nerve
terminal
CCS glass vial
30mg/ml 4 isomer l isomer active
15/30/60mg tablets
elixir 3mg/ml
0.5 &1% nasal drops
Iv rapid
Im or sc longer duration
Rapid and complete absorbed o, im
sc,
No quantitative data available
Pharmacokinetics
Absorption iv rapid &lasts 5-10mins
im or sc takes 15min lasts
1hr
Distribuin
Metabolism MAO in Liver
Excretion
CNS
No stim effects
GIT
GU
↓Renal BF
Uterus
Crosses placenta
Resistant to MAO and COMT
Liver oxidation, demethylation,
aromatic hydroxylation
90% renal unchanged
t1/2 6hrs
Lasts 15mins or 1hr im
Pharmacodynamics
CVS
↑SVR and BP.
Reflex brady
=↓CO
not arrythogenic
RESP
↑SVR and BP.
Reflex brady
↑CO HR BP CBF
↑CMyoRO2
may ppte arrythmias
Respiratory stimulant
Bronchodilation
↑CBF, stimulatory
mydriases
Anti nausea. Relaxes GI SM
↓Renal BF ↓GFR
relaxes detrusor and contracts
sphincter
↑SVR ↑BP
Reflex brady
=↓CO
↑ CBF by indirect mech.
↑PVR
slight ↓RR and ↑TV
↓CBF
↓Renal BF
Contraction of pregnant uterus
Results in more favourable
cord gas profile – not
widespread use due to OD
risk
metabolic
Other
CCS glass vial
10mg/ml
Hyperglycaemia. Glycogenolysis,
lipolysis
Caution with MAO