Формотерол

solid

Labeled Formoterol, intended for use as an internal standard for the quantification of Formoterol by GC- or LC-mass spectrometry.

ChEBI: A phenylethanoloamine having 4-hydroxy and 3-formamido substituents on the phenyl ring and an N-(4-methoxyphenyl)propan-2-yl substituent.

Formoterol (Foradil) isalso a lipophilic (log P= 1.6) and long-acting β2-agonist. Ithas 3'-formylamino ( β-directing) and 4 OH groups on onephenyl ring and a lipophilic -directing N-isopropyl-pmethoxyphenylgroup on the nitrogen atom. Its long DOA(12 hours), which is comparable to that of salmeterol, hasbeen suggested to result from its association with the membranelipid bilayer, from which it gradually diffuses to provideprolonged stimulation of β2 receptors and its resistanceto MAO and COMT. Formoterol has a much faster onset ofaction than does salmeterol as result of its lower lipophilicity.Both of these long-acting drugs are used by inhalationand are recommended for maintenance treatment of asthma,usually in conjunction with an inhaled corticosteroid.

Formoterol has 3′-formylamino and 4′-hydroxy ring R3 substitution pattern but also an alkoxyphenylethyl lipophilic group R1 on the nitrogen, similar to ritodrine. Although it is less lipophilic (log P = 1.6) than salmeterol, it has a 12-hour duration of action similar to that for salmeterol. It is administered as an inhaled dry powder, because it is unstable to heat and moisture. It is a mixture of (R,R)-(–)- and (S,S)-(+)-stereoisomers, with the (R,R)-isomer having approximately 1,000-fold more affinity for the β2-receptor than the (S,S)-isomer. Because of its high potency and low dose, however, there is no clinical advantage for using (R,R)-formoterol as bronchodilator compared to the racemate. Unlike salmeterol, formoterol has a faster onset of action as a result of its lower lipophilicity. It is also more potent; a 12-μg dose of formoterol has been demonstrated to be equivalent to a 50-μg dose of salmeterol.