Selective Alpha 1 blockers are ending with suffix like “-zosin” and include drugs like prazosin, doxazosin, terazosin and alfuzosin. All these drugs act as vasodilators and can be used as antihypertensives while the last drug alfuzosin is more preferred for treatment of BPH just like alpha1a-blockers such as tamsulosin and silodosin.
Hi everyone today in this video let us discuss about the select two alpha one blockers let us discuss the chemistry and structural activity relations associated with the select to alpha on blockers what are the alpha blockers we have few other drugs which are ending with the suffix josein for example drugs like prazosine doxazosine pterazosine and alphyosine all
These drugs are selectively blocking the alpha receptors and these alpha receptors are present on the various smooth muscles particularly they are present on the vascular smooth muscle so these decks are acting like smooth muscle relaxants as well as the vasodilators as these decks are producing the vasodilation by directly blocking the alpha receptors on the
Vascular smooth muscle these drugs are useful as antihypertensives in the emergency treatment of hypertension similarly another set of drugs are there which are ending with the suffix ocean like the tamsulosin and cylodocine so these two tracks are selectively blocking the alpha-1a receptors present on the bladder and prostate tissue that’s why these acts are
Using the treatment of bph benign prostatic hyperplasia similarly alphyosin is also used in the treatment of benign prostatic hyperplasia so within the alpha blockers few of the drugs like the progestin doxazosin terrazosine are more preferred as vasodilators and other drugs like the alpha ocean tamsillosing and cylodocin are particularly used in the treatment of
Benign prostatic hyperplasia now let us see what are the structural features and scr related with these alpha and blockers so this is a general structure of the alpha one blockers which are ending with the suffix zosin like the pros ocean doxazos in terrazine and alphyosin these drugs are hanging three important structural features the first one there has a six
Plus six membered heterocyclic ring system this is nothing but the quinazoline we know that quinoline is having the single nitrogen but when it is having an extra nitrogen at the third position we call the quinazoline and this kuna jolin ring is attached by another ring this is the piper’s inviting and finally this piper’s in mode is attached with a ssl moiety
In this way all four blockers are in the three structural features one is the quinazoline ring second one is the pipe resin ring third one is the sl chain so here we can store the membrane for the quinoa jolene ring from the nitrogen so this is one two three four five six seven eight in most of these alpha blockers we can observe the methoxy groups at sixth and
Seventh position and amine group at the fourth position now let us see what is the scr related with the all these three structural features that is aquino jolin moiety piper zen moiety and sl moiety so let us start with the first one queen azolen ring so within this structure we can observe the queen of jollen ring so most of the all found blockers are hanging the
Kunazole in moiety but in the select two alpha one a blockers like the tamsulosin and xylodoxine we cannot observe this queen of jolen ring so quenazoline ring is present in the drugs which are ending with the suffix zosin now within this quenojolen ring at the fourth position we can observe one of the group this is the amine group so four amino group is essential
For activity of the alpha one blockers if this group is going to be removed they cannot block the alpha receptors because this group is responsible for the binding of these diags with the alpha one receptors second one is a piper joint chain so within this structure we can observe that the pythagorean ring is going to connect the quinazoline ring to the acell
Moiety so this ring is important but this ring can be replaced with the other rings for example this piper’s in ring can be replaced with the pipe rendering system otherwise it can be replaced completely with a alkyl amino chain so piperagin ring can be replaced with the other structures which are having the nitrogen like the piperidine or alkyl amino chains
Which are connecting the cell moiety with the financial entering system third one is the sl chain so now the third part is the sl chain which is more important this sl chain is responsible for the pharmacokinetic properties of the track so this sl chain influence the duration and bioavailability of the drugs for example when we see the duration we can observe
A relation like that d is greater than t is greater than p that means the doxazosin is having the more duration compared to the terrazine which is hanging more duration than the project so we can easily remember this sequence as dtp doxazosin terazosine protocin but when we come to the bioavailability we can observe a somewhat difference in the sequence we can
Observe a sequence of tdp terrazine is having more viability than the doxazosin then progressing so biolobility is more for terazosine duration is more for doxazosine in this way sl chain will influence the pharmacokinetic properties like the distribution of the drug in the body which influence the duration and viability and these alpha blockers are having the
Similar structure at the queenosola in hypergen moiety and they are going to differ only by sl chain so now let us see what are the structures of the alpha one blockers first one is the prosocian we can observe that in the progeosine the cell chain is formed by furon oil moiety so a furon ring is attached through a carbonyl group to the piper chain now what is
The name of this uh pros ocean now let us give the numbering to the queen azole and morty so this is one two three four five six seven eight now this queen of solenoid is attached to the pipers and chain by second position but here what is the principal function group the principal function group is the ketone so we have to give the preference to the ketone
Such that the suffix of the name becomes methanol now this methanol is attached with the two chains one is the furon attached by second portion so on two i and another one is the five percent chain attached by first portion but this pythagorean chain is having the another side chain at the fourth position so we can write this as four dash pipers in one eye now
At the fourth portion of this piper gene the queen of jordan white is attached so this queen of solenoid is hanged up amino group at the fourth portion so four am i know it is having the methoxy groups at the sixth and seventh portion so six seven dimethoxy so we can fill in this gap four amino six seven dimethoxy quinozole in two oil that completes the name of
The progeosin so pragersin is having a furon oil moiety as the sl chain second one is the terrazine terrazosine is a similar structure where the furon is going to be saturated such that it is going to be converted to tetrahydrofuran mighty now again we can give the numbering to the quenesvolen mighty like this and here again the ketone forms a principal function
Group so the suffix is the methanol this methanol is attached with the tetrahydrofuran ring but we can consider this as oxygen containing saturated system so that is oxalon to iron so now we can consider this as auxillon twile then remaining is same four pipers in one eye four amino six seven dimethoxy equinox all in two oil that is nothing but the terrazine
So projocine is having the furon whereas terrazin is having the tetrahydrofuran third one is that doxazosin doxazos is having somewhat large structure as an acyl moiety now again here the principle function group is the ketone so this is the methanol but this method is attached with the one of the chain what is the name of this chain so this ring is having the
Benzene attached with the six membering system with two auxins so we can write this as one four benzyl dioxin 2i but it is somewhat saturated at the second and third portion so we can write 2 three dihydro one for benzodioxin two oil that is a ring system present as an sl moiety and then the remaining is same it is four dash pipers in one aisle and four amino
Six seven dimethoxy quinozole into oil that is the doxazosin so doxazosin is having one of the ring system that is nothing but the 2 3 dihydro one for benzo dioxin two oil which is attached to the ketone and doxa juiciness is having the long duration of action because of this sl moiety next one is the alfie zosin you can observe that alpha joseph is not having any
Piper’s entering system but it is having an open chain that is connecting the in moiety with the acid moiety now this is the numbering for the quenazoline ring system and what is the principal function group here here the principal functional group is the carboxamide this carboxymide is attached to the tetrahydrofuran just like in the terrazosine the stator height
Of uranus can be considered as an oxalain so now this is nothing but the oxaline 2 carboxamide that is a suffix of the name and then on the nitrogen we can observe the profile chain three carbon chain so end propyl and this propyl side chain is attached with a methyl amino at the third portion so three methyl amino and this methyl amino group is attached with the
Queenazole in moiety now the rest of the name is similar to the other drugs so this is 4 amino 6 7 dimethoxy quinozole in 2 i that is the alpha ocean so you can observe that in the progressing dioxazine terzosine and alpha ocean and all of these drags the amino group at the fourth portion is always present which is essential for the activity and pythagorean chain is
Required but which can be replaced with the other chains just like in the alpha ocean we can observe a alkyl amino chain and the sl moiety mainly influence the duration and bioability of these drugs next one is the select to alpha on your blockers we have two drugs like that tamsilosine you can observe time solution is not having any equinox in moiety this is one
Of the select to alpha one a blocker which is used in the treatment of benign prostatic hyperplasia and similarly another drug is the cylodocyne this is again selected for the alpha-1a receptors and used in the treatment of bph in this way most of the alpha blockers are hang the three important uh structural moieties queenazole in moiety piper zenomoity and excel
Moiety these structural features are not observable select to alphania blockers like the timeslosion and xylodocin which are used in the treatment of bph so that’s about the alpha blockers hope you have enjoyed this video if you like this video please subscribe to our channel share this video with your friends post your comments in the comment box thank you for watching this video
Transcribed from video
Alpha1 blockers – Chemistry and SAR By egpat
