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Physiological effects of medications on Plasma/Urine metanephrines

 

 

Class of Drug

 Example

 Mechanism of Action

 Effect

Tricyclic antidepressants

Amitriptyline, Clomipramine, Dosulepin

Block NA re-uptake

Increase plasma and urinary NA, NMA and VMA

Tricyclic antidepressants (acute administration)

Amitriptyline, Clomipramine, Dosulepin

Suppress release of NA from sympathetic nerves

Decrease plasma NA

Selective serotonin reuptake inhibitors

Citalopram, Fluoxetine, Sertraline

Block NA re-uptake

Increased NMA

Selective noradrenaline reuptake inhibitors

Venlafaxine

Inhibit NA and A re-uptake

Increase NMA

Calcium channel blockers

Amlodipine, Diltiazem

Activate sympathetic nervous system

Increase plasma NA and A

a-adrenergic receptor blockers (selective)

Doxazosin, Indoramin

No effect

a-adrenergic receptor blockers (non-specific)

Phenoxybenzamine

Block pre-synaptic a2-adrenoceptors, attenuates alpha receptor feedback inhibition

Increase plasma and urinary NA, NMA and VMA

β-adrenergic receptor blockers

Atenolol, Propranolol, Oxprenolol

 

Increase plasma MA

Mono amine oxidase inhibitors (MAOI)

Phenelzine, Isocarboxazid

Block conversion of NA and A to DHPG

Up to 5 fold increase in plasma and urinary NMA and MA

Stimulants

Caffeine, Nicotine

Activation of adrenergic receptors

Increase plasma and urinary A and NA

Sympathomimetic factors

 Amphetamine, Ephedrine

 Activation of adrenergic receptors

 Increase plasma and urinary A and NA

Dopaminergic drugs

 Levodopa

 Metabolised by enzymes that also convert catecholamines

 Increased plasma and urinary A and NA

Centrally acting anti-hypertensive drugs

 a-methyldopa

 Metabolised by enzymes that also convert catecholamines

 Increased plasma and urinary A and NA

NA – noradrenaline, A – adrenaline, NMA – normetadrenaline, MA – metadrenaline, VMA – 4-hydroxy-3-methoxymandelic acid, DHPG – dihydroxyphenyglycol.4-6 

References

  • Neary NM, King KS, Pacak K. Drugs and phaeochromocytoma – Don’t Be Fooled by every Elevated Metanephrine. New Eng J Med. 2011;364:2268-70.
  • Eisenhofer G, Goldstein DS, Walther MM et al. Biochemical diagnosis of phaeochromocytoma: how to distinguish true from false positive test results. J Clin Endocrinol Metab 2003; 88:2656-66.
  • Lenders JW, Eisenhofer G, Mannelli M, Pacak K. Phaeochromocytoma. Lancet 2005; 366: 665-675.

 

The page has been prepared by Andrew S Davison, Newcastle upon Tyne NHS Foundation Trust


JHB 26/06/2012
 

 

 

 

 

  

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