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Definition
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| Intermolecular forces Based on |
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Definition
Functional groups
H-bonding |
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| Molecular Weight Based on |
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Definition
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Term
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Definition
Solubility
Absorption
Elimination |
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| Intermolecular forces Affects |
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Definition
Solubility
Plasma protein binding |
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Definition
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Term
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Definition
Changes in pH of the drug solution in case of IV/parenteral dosage forms and changes in GI pH incase of oral dosage forms can affect the solubility of drugs by affecting the ionization states of drugs
Addition of compounds with varying degree of acidity or basicity can alter the pH of parenteral dosage forms
In parenteral dosage forms changes in pH can lead to precipitation of drugs from the solution
Mixing of acid and base in parenteral formulation is not recommended due to formation of precipitate
In case of oral formulations, the changes in pH affects absorption and bioavailability of drugs by decreasing solubility
Drugs altering gastric pH such as antacids should not be co-administered with certain drugs as antacids can decrease the therapeutic effects of the drugs
Antacids such as Calcium carbonate (TUMS®), Aluminum hydroxide (Mylanta®), Sodium carbonate (Alka-Seltzer®) and Magnesium hydroxide ( ingredient of Maalox®) can decrease absorption of drugs |
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Term
| Cation-Anion Interactions |
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Definition
Interaction between a weekly acidic drug and weekly basic drug will result in a salt which will have poor dissociation properties and poor aqueous solubility
The solubility is also dependent on the molecular weight of the salt
Salt resulting from two drugs generally will have poor solubility
Mixing of acidic and basic drugs in an IV bag is not recommended due to generation of insoluble salt |
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Term
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Definition
Chelation is term used to describe complex of organic molecules with metals such as iron, calcium, mercury, magnesium etc.Chelate is typically large in molecular size with poor water solubility
Chelates of drug molecules with metal ions have poor absorption and decreased bioavailability |
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Term
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Definition
Ion- exchange resins are commonly used in the management of hyperlipoproteinemia
Ion-exchange (IE) resins binds to Bile acid (BA) in the GI lumen to from a non-absorbable complex preventing reabsorption of BA
IE resins can bind to drugs and decrease the absorption by forming large complexes
The dose of IE resin and other drugs should be well spaced |
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Term
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Definition
Forces of Interactions:
Electrostatic Interactions
-NH3+ of lysine and N-terminal amino acids
-NH2+ of histidine and -S- of cysteine
-COO- of aspartic and glutamic acid
van der Waal’s forces
Dipole - dipole
Hydrogen bonding
Plasma protein has specific binding sites for drugs
Drugs bound to plasma protein can be displaced by other drugs having high affinity for the same binding site on plasma protein
Displacement from plasma protein binding sites will increase the serum concentration of the drugs
Increase in serum concentration may accentuate the toxicity of the drug
E.g. Aspirin can displace NSAIDs from plasma protein binding site increasing the side-effects of NSAIDs |
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