PHENYLEPHRINE is a sympathomimetic substance (it stimulates the sympathetic nervous system and either acts like adrenaline or increases adrenaline production)... in this case, P.E HCL (MIMICS) adrenaline by activating (selectively) the Alpha-1-adrenergic receptors...this causes constriction of blood vessels in the nasal mucosa and also elsewhere in the body / brain.
Side-effects of the drug include.
- Changes in heart rate (increase, or more commonly decrease) (1) (2)
- Increased blood pressure. (3) (4) (5)
- Anxiety, paranoia, Agitation.
- Changes in cognitive ability.
- Decreased resistance to psychological stress.
- Erectile Dysfunction (11) (12) (13) (14)
- Decreased oxygen delivery to frontal lobe. (7)
~NOTATIONS~
Phenylephrine, like adrenaline, constricts blood vessels in the brain and body - this is the basis for it's benefits in the nasal passageways..but also the basis for it's side-effects. The research also makes for an interesting leap and / or reinforcement in violent behavior - as alpha-1-agonists decrease oxygen to the frontal lobe - it may be worth noting that adrenaline by the alpha-1-receptor may play an activating role on sociopathic/remorseless behavior...this does not mean phenylephrine will cause one to become murderous -- but it may affect behavior by affecting oxygen delivery even in previously unaffected individuals.
ALPHA-1-ADRENERGIC ACTIVATION GENERALLY DECREASES HEART RATE
Because alpha-1-activation has a tendency to increase blood pressure (actually, it always does) - the heart rate naturally goes down to compensate for alterations in vascular tone and reduced blood flow. The heart rate usually goes up when one is scared or nervous , so it's possible that this occurs in some situations of phenylephrine intake....especially in those with an anxiety disorder...however, in most individuals - it will decrease heart rate ...in proportion with blood pressure increases...if your blood pressure is LOW - heart rate may also go up - again, to compensate for lack of blood flow and ensure blood is flowing to/in the extremeties. The difference is dilation is generally healthier for all body tissues.
When heavy exercise and lifting occurs - alpha-1-receptors naturally become either blocked or downregulated - so some of the benefit of exercise on the heart and blood flow comes from the eventual BODILY derived alpha-blockade.... (!) (!!) (!!!)
