Physicochemical Properties of Drugs :- General Considerations Chapter of Medicinal Chemistry - I

Physicochemical properties of  drugs can affect drug action and absorption.

◼️ pH partition hypothesis 

◼️ Hydrogen bonding

◼️ Ionization 

◼️ Oxidation - reduction potentials 

◼️ Fergusons principal

◼️ Bioisosterism 

◼️ Solubility  

➤ pH partition hypothesis :-  The pH partition hypothesis tells us about the optimum pH and lipophilicity as essential parameters required for the biological action and also absorption of the molecule from the site of action.

Know the more details of  pH partition hypothesis  CLIK ON ⏬  DOWNLOAD ⏬ PDF 

➤ Hydrogen bonding :-                                                                                                                                

 Hydrogen bonding is essential for,                                                                                                              

(i) Water solubility of the molecule                                                                                                            

(ii) interaction with the receptor 

Functional group donate and accept hydrogen and thus contribute towards hydrogen bonding as well as solubility of the drug molecule . The functional group does not form intermolecular hydrogen bond will not enhance hydrophilicity will be hydrophobic in nature. 

Know the more details of  Hydrogen bonding CLIK ON ⏬  DOWNLOAD ⏬ PDF 

➤ Ionization :- Ionization is expressed as function of dissociation constant pKa is the negative logarithm of dissociation constant pka determines the amount of drug that is ionized and that which remains unionized. ionization is expressed by Henderson - Hasselbalch equation.

 Know the more details of Ionization CLIK ON ⏬  DOWNLOAD ⏬ PDF

➤ Oxidation :- reduction potentials :- Redox potential is defined as compounds ability gain or donate electrons. Oxidation reduction potentials are in existence with the chemical molecule only and are the only correlation with biological activity. In reality biological systems do not have redox systems.

Know the more details of Oxidation - reduction potentials CLIK ON ⏬  DOWNLOAD ⏬ PDF

➤ Fergusons principal :- Fergusons observed number of physical characteristics partition coefficient vapour pressure solubility in water effect on surface tension of water and capillary activity which are altered with geometric progression. 

 Know the more details of Fergusons principal CLIK ON ⏬  DOWNLOAD ⏬ PDF

➤ Bioisosterism :- Bioisosterism substituents or groups that have similar chemical or physical properties and that shows similarities in biological properties.

 Know the more details of Bioisosterism CLIK ON ⏬  DOWNLOAD ⏬ PDF

➤ Solubility  :- 

There are three types of solubility 

(i) Lipid solubility 

(ii) Aqueous solubility 

(iii) Salts

Know the more details of Solubility There are three types of solubility                                              CLIK ON ⏬  DOWNLOAD ⏬ PDF