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Previously we said that the adrenergic agonists are divided to three main groups according to their mechanism of action direct acting indirect acting and mixed action adrenergic agonists and in the previous two lectures we discussed the first type of them the direct acting adrenergic agonists they were about 15 different agents that we discussed their actions uses
Adverse effects and brand names today we’ll discuss the indirect acting and mixed action agents don’t worry about writing down you’ll find the lectures pdf down in the description let’s start as we said before the indirect acting adrenergic agonists cause the release inhibit the reuptake or inhibit the degradation of epinephrine or norepinephrine they potentiate
The effects of epinephrine or norepinephrine produced endogenously but do not have a direct effect on the postsynaptic receptors amphamine the first thing you should know about it that it has a strong stimulant effect on the cns and it is highly addictive drug amphtamine acts by releasing intracellular stores of catecholamines such as norepinephrine and dopamine it
Also inhibits male and is a weak reuptake transport inhibitor so high levels of catecholamines are readily released into synaptic spaces leading to a marked cns stimulation and an increase in blood pressure and heart stimulation its therapeutic use is limited due to psychological and physiological dependence but it is used in certain conditions such as attention
Deficit hyperactivity disorder or known as adhd which is a condition in some young children characterized by hyperkinetic and lack the ability to be involved in any activity for longer than a few minutes it is also used in narcolepsy which is a relatively rare sleep disorder that is characterized by uncontrollable bouts of sleepiness during the day and also used
In appetite suppression more information about amphtamine and its derivatives will be discussed in the cns lectures tyramine is another agent that enhances the release of catecholamines from nerve terminals increasing their concentration in synapse and potentiating their effects actually it is not a clinically useful drug but it is important because it is found in
Fermented food such as aged cheese and chianti wine it is a normal byproduct of tyrosine metabolism normally it is oxidized by mao in the gastrointestinal tract but it can precipitate serious the suppressor episodes in patients receiving mal inhibitors cocaine is a widely available and highly addictive drug it acts by blocking the reuptake of the catecholamines into
The presynaptic terminals thus increasing the amount of catecholamines available at the synapse and this potentiates and prolongs the cns and peripheral actions of these catecholamines the prolongation of dopaminergic effects in the brain’s pleasure system which is called the limbic system produces the intense euphoria that cocaine initially causes but chronic
Intake of cocaine depletes dopamine and that triggers craving for cocaine that temporarily relieves severe depression more information will be discussed in the cns lectures now let’s talk about the last type of the adrenergic agonists the mixed-action adrenergic agonists they both act by enhancing the release of stored norepinephrine from nerve endings and also
Directly stimulate both alpha and beta receptors such as ephedrine and pseudoephedrine they are not catecholamines and are poor substrates for comet and mao so they have a long duration of action they are absorbed orally and they penetrate into the cns but pseudoephedrine has fewer cns effects ephedrine is eliminated largely unchanged in urine and pseudoephedrine
Undergoes incomplete hepatic metabolism before elimination in urine ephedrine produces a mild cns stimulation it also raises systolic and diastolic blood pressures by vasoconstriction and cardiac stimulation it also produces bronchitis but it is less potent and slower acting than a pineaphrin or isoproterenol so it can be used to prevent asthma attacks it can
Also be used as oral nasal decongestant pseudoephedrine is primarily used orally to treat nasal and sinus congestion but it has been illegally used to produce methamphetamine so products containing pseudoephedrine have certain restrictions that’s all for this video if that was useful for you please leave like or comment in the upcoming lecture we’ll start talking
About the adrenergic antagonists so subscribe if it’s your first time here and keep following us
Transcribed from video
Pharmacology [ANS] 16- Indirect Acting Adrenergic Agonists [Amphetamine – Cocaine – Pseudoephedrine] By Medical Videos [ ANIMATED ]
