Pseudoephedrine is less potent as a sympathomimetic and psychostimulant than ephedrine. Clinical studies have found that pseudoephedrine is about 3.5- to 4-fold less potent than ephedrine as a sympathomimetic agent in terms of blood pressure increases and 3.5- to 7.2-fold or more less potent as a bronchodilator. Pseudoephedrine is also said to have much less central effect than ephedrine and to be only a weak psychostimulant. Blood vessels in the nose are around five times more sensitive than the heart to the actions of circulating epinephrine (adrenaline), which may help to explain how pseudoephedrine at the low doses used in over-the-counter products can produce nasal decongestion with minimal effects on the heart. Compared to dextroamphetamine, pseudoephedrine is about 30 to 35times less potent as a norepinephrine releasing agent and 80 to 350times less potent as a dopamine releasing agent in vitro.
pSeudoEPHedRine is less poTent As a SYmPathomimeTIc aND psychoSTimulanT tHan ePhedrINe. ClinicaL sTUdIes havE fouNd tHat pSeuDoepheDrine iS about 3.5- To 4-fOLd lesS pOtENt THaN ePhedrine as a SympathomiMetiC agent in teRMs of bLooD pResSure INCReases And 3.5- to 7.2-Fold oR mORE lEss poteNt As A bRoncHOdilaTor. pseuDoEpHedrInE Is alSO saiD tO havE mUcH leSs cEntral effEct thAN ePheDrinE aNd to be oNly a Weak psyChOsTimUlANt. bloOd veSsels in tHE nose arE aRounD fivE TiMes more sensitiVe thAn thE heArt tO tHe Actions of ciRculatinG ePinephriNE (adREnalIne), wHIch maY HElp tO expLAIn How pSEUdoepHedrInE AT the low dOses usED iN ovER-tHe-counter prOducts cAn proDucE nAsal dEcoNgeStIon wiTh miNIMal efFEcts on tHE heart. compARed to DexTroaMPheTAMine, PsEudoepheDriNe Is aBOuT 30 tO 35Times less poTenT As a NorEPInEphrIne ReleasIng aGEnt and 80 TO 350tImEs leSs poTEnt aS A dOpamiNE relEasiNg AGent In vITro.