Acidic drugs

The n-octanol/water partition coefficient logP in Table 1.8 was determined by the shake-flask method, as described in detail (70). [Pg.34]

The extrapolated retention factors logkzu were determined on a BDS C18 column using methanol as organic modifier and with different amounts of n-octanol as the mobile phase additive. For more polar compounds, the effect of n-octanol in retention was found to decrease as their lipophilicity was increasing. In the case of carboxylic acids and oxicams, the differentiation in retention, in presence and absence of n-octanol, could be attributed to the attenuation of polar interactions, concerning mainly hydrogen bonding (69). [Pg.34]

At a pH of 2.5, the use of a n-octanol saturated buffer, without further addition of n-octanol in the mobile phase, led to an 1 1 correlation with the logarithm of n-octanol/water partition coefficient logP. AtaphysiologicalpH,an 1 1 correlation was obtained between logDjA (69). [Pg.34]

Increasing the gastric pH, which causes a decrease in absorption of weakly acidic drugs and results in a decreased drug effect (eg, digoxin, phenytoin, chlorpromazine, and isoniazid)... [Pg.471]

Stein D, Foster E, Huang SB, Weller D, Summerton J (1997) A spedfidty comparison of four antisense types morphoUno, 2 -0-methyl RNA, DNA, and phosphorothioate DNA, Antisense Nucleic Acid Drug Dev 7 151-157... [Pg.261]

Koppelhus U., Awasthi S.K., Zachar V., Holst H.U., Ebbesen P., Nielsen P. E. Cell-dependent differential cellular uptake of PNA, peptides, and PNA-pep-tide conjugates. Antisense Nucleic Acid Drug Dev. 2002 12 51-63. [Pg.176]

McMahon B.M., Mays D., Lipsky J., Stewart J.A., Fauq A., Richelson E. Pharmacokinetics and tissue distribution of a peptide nucleic acid after intravenous administration. Antisense Nucleic Acid Drug Dev. 2002 12 65-70... [Pg.176]

SuMMERTON J., Weller D., Antisense Nucleic Acid Drug Dev. 1997, 7, 187-195. SuMMERTON J., StEIN D., HuANG S., Matthews P., Weller D., Partridge M., Antisense Nucleic Acid Drug Dev. 1997, 7, 63-70. [Pg.219]

The rate of release of levonorgestrel from films of block copolymers of e-caprolactone and dl-lactic acid (drug load 30%) was shown to be a function of the copolymer composition. The rate was unchanged for compositions of 100% and 88% e-capirolactone, but decreased thereafter as the e-caprolactone content decreased (42). [Pg.88]

Figure 31-1. Biosynthesis of hippurate. Analogous reactions occur with many acidic drugs and catabolites.

Generally it is only the non-dissociated or unionised drug that is lipid-soluble and a drug s degree of ionisation depends on its dissociation constant (pA) and the pH of the environment in which it finds itself. For an acidic drug this is represented by the Henderson Hasselbalch equation as... [Pg.112]

Thus an acidic drug with a relatively low pK of 3 will be largely unionised (hundredfold) in the acidic environment (pH = 1) of the stomach since... [Pg.112]

UETAL. Poly(a-amino acid) Drug Conjugates... [Pg.113]

By comparing gastric absorption at pH 3 and pH 6 where surface area and factors other than pH are constant, one sees that the general principle is supported acid drugs are more rapidly absorbed from acidic solution, whereas basic drugs are more rapidly absorbed from relatively alkaline solution. [Pg.43]

Acidic drugs are more rapidly absorbed from the intestine (pH 6), although there is substantial ionization, compared to the rate of gastric absorption, even at a pH where the drug is in a far more acidic solution (pH 3). Again, this is primarily a result of surface area differences. [Pg.43]

Ketoprofen, a weak-acid drug, with a pKa 4.12 (25°C, 0.01 M ionic strength), was selected to illustrate Eqs. (7.20) and (7.21) in a series of simulation calculations, as shown in Fig. 7.16. The membrane-buffer apparent partition coefficients /(piii were calculated at various pH values, using the measured constants from... [Pg.146]

Figure 1 Stagnant film model for dissolution of acidic drug (HA) in solution with base (B). (From Ref. 2.)...

The derivation and experimental verification of the MMHS model represented a significant accomplishment and a natural plateau for film models. To be sure, there are general criticisms of film models and more specific criticisms of the MMHS model [6], However, overall the MMHS model should be recognized as a robust but simply applicable model which serves to demonstrate how factors such as intrinsic solubility of the acid drug, ionization and pA of the drug, and concentration of the reactive base all contribute to increasing the dissolution rate and mass transfer. [Pg.131]

Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...