Phenylephrine structure

FIG. 17 Chemical structures of (a) epinephrine hydrochloride, (b) dopamine hydrochloride, (c) isoproterenol hydrochloride, (d) phenylephrine hydrochloride, (e) tolazoline hydrochloride, (f) oxyprenolol hydrochloride, (g) alprenolol hydrochloride, and (h) propranolol hydrochloride. 

The chromophore of phenylephrine is not extended but its structure includes a phenolic hydroxyl group. The phenolic group functions as an auxochrome under both acidic and alkaline conditions. Under acidic conditions it has two lone pairs of electrons, which can interact with the benzene ring and under basic conditions it has three. Figure 4.11 shows the bathochromic and hyperchromic shift in the spectrum of phenylephrine, which occurs when 0.1 M NaOH is used as a solvent instead of 0.1 M HCl. Under acidic conditions the X max is at 273 and has an A (1 %, 1 cm) value of 110 and under alkaline conditions the X max is a 292 nm and has an A (1%, 1 cm) value of 182. 

Nasal Decongestants for Systemic Use Sympathomimetics (pseudoephedrine, phenylpropanolamine, phenylephrine) and structural analogues (epinephrine, ephedrine)... 

Phenylephrine is a synthetic sympathomimetic amine structurally similar to epinephrine. It acts primarily on ai receptors and has little or no effect on (3 receptors. A minor part of its pharmacologic effects may be attributed to release of norepinephrine from adrenergic nerve terminals. 

Phenylephrine is a selective ai adrenergic agonist, with a pharmacological structure similar to norepinephrine (noradrenaline), which causes peripheral vasoconstriction. Stimulation of adrenoceptors in the myocardium has an inotropic effect. However, phenylephrine produced no increase in cardiac output, increased systemic vascular resistance and mean arterial pressure and reduced muscle blood flow in anaesthetized horses (Lee et al 1998). Phenylephrine should be reserved for critical conditions where the perfusion of essential organs is compromised and inotropes are not effectively maintaining organ function. The recommended infusion rates are shown in Table 12.3. 

Phenylephrine. Phenylephrine (Nco-Syncphrinc structure shown above under "Structure-Activity Relatim-ships ) is the prototypical selective direct-acting o- -recc xe agonist. It is a potent vasoconstrictor but is le.ss potent ihr... 

Activation of serotonin receptors in canine femoral VSMC evoked tyrosine phosphorylation of a group of substrates similar to those that were tyrosine phosphorylated during stimulation of a -adrenergic receptors with phenylephrine (Fig. 8A). Preincubation of the cells with 110 xM genistein suppressed tyrosine phosphorylation that was evoked by stimulation of either serotonin or adrenergic receptors (Fig. 8A, lanes 4 and 5). The same concentration of genistein that inhibited receptor-activated increases in [Ca +Jj (Fig. 5) also inhibited receptor-activated increases in protein tyrosine phosphorylation. In contrast, preincubation of the VSMC with 110 xM diadzein, a structural analog... 

As shown in Fig. (14) , compounds 1-5 inhibited phenylephrine-induced vasoconstriction. Compounds 1, 2, 3, 4 and 5 were identified as xanthoangelol, 4-hydroxyderricin, and xanthoangelols B, E and F, respectively, based on the comparison of their spectral data with those of authentic samples. The structures of the five isolated active substances are shown in Fig. (15) . 

Schieffer, G.W. Smith, W.O. Lubey, G.S. Newby, D.G. Determination of the structure of a synthetic impurity in guaifenesin modification of a high-performance liquid chromatographic method for phenylephrine hydrochloride, phenylpropanolamine hydrochloride, guaifenesin, and sodium benzoate in dosage forms. J.Pharm.Sci., 1984, 73, 1856-1858... 

Identify the structural features/functional groups of phenylephrine and guaifenesin that contribute to improved water solubility (medication given as drops). List the type(s) of interactions that these groups have with water, and draw an example of these interactions (with appropriate labels) below. 

Figure 4-13shows the molar fractions of phenylephrine as functions of pH. Obviously in phenylephrine deprotonation of die ammonium cationic site is preferred to deprotonation of the phenolic function. Details of basic principles, hardware and software concepts and applications of NMR-controHed titrations are described in [14], [15], [16], [17], [18], [19], [20], [21], [22], Results from more laborious UVA7is [23], [24] and now the easily accessible automated NMR-controlled titrations of phenylephrine [22] are consistent The method of NMR-controlled titration is a powerful tool in analytical and structural chemistry, and was recently applied successfully to a series of biorelevant phosphorus compounds [18],[19],[20],[21],... 

The small CD activity of the guest (lAsI <0.2) may be enhanced successfully to be detected easily as a readout in the CD spectrum (Ae -i-8.8) (chiroptical enhancement). This protocol was applied to the detection of a (-)-phenylephrine-H+ salt 3 (lAsI <0.2) to give an enhanced readout (Ae -i-9.6). For the anti-atropisomer (anti-1), no chiroptical signal was induced on the addition of (R,R)-2 or (-)-phenylephrine-H+ salt 3 due to a non-propeller-shaped structure. 

Figure 5.15. Molecular structure of methamphetamine Figure 5.16. Molecular structure of phenylephrine Figure 5.17. Molecular structure of paclitaxel Figure 5.18. Molecular structure of S-citalopram Figure 5.19. Molecular structure of S-sertraline...

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