IONISED
POLAR
Water-soluble
Lipophobic
Hydrophilic
Do not cross membranes readily
ACIDIC drugs bind to ALBUMIN
ACIDS are ionised in BASIC media
BASIC drugs bind to α1-GLYCOPROTEIN
BASES are ionised in acidic media
UNIONISED
NON-polar
Fat soluble
Hydrophobic
Lipophilic
Diffuse more readily across a membrane
Very HIGH L-WDC
Distributes widely through the body
Acts in the CNS (crosses the bbb by PASSIVE DIFFUSION)
Weak ACIDS
HA A- + H+
¿ IONISED
pH= pKa + log10 A− HA ¿ Ratio = UNIONISED
With a dissociation constant K
a
Weak BASES
BH+ B + H+