Drug Metabolism

What is one of the factors that could cause significant changes in biological activity of a drug?

How was the initial receptor model based on the interaction between drugs and receptors?

What can happen when a drug docks with a receptor based on the text?

How is the drug-receptor association depicted in the text?

What is the significance of the first-pass effect mentioned in the text?

Why is lidocaine impractical to administer orally?

How does the rapid metabolism of lidocaine benefit patients with cardiac arrhythmias?

What development was inspired by the understanding of the metabolic labile site on lidocaine?

What does the pKa measure?

Where does the equilibrium lie for a strong acid in water?

What does a high pKa value indicate about a weak acid in water?

What does a pKa for a base actually represent?

What is the relationship between pH and percent ionization of an HA acid when the pH is 1 unit greater than the pKa?

How does an increase of 2 pH units affect the ionization of a BH+ acid?

What is the impact of increasing the hydrogen ion concentration on drug equilibrium?

At what pH value would an HA acid be 50% ionized?

Why is it impractical to administer lidocaine orally?

What happens to lidocaine when administered intravenously for cardiac arrhythmias?

What is a significant characteristic of lidocaine's first-pass effect?

What led to the development of tocainide according to the text?

Which factor contributes to the drug-receptor interaction process by favoring the desired pharmacological response?

Why are second-generation antihistamines like fexofenadine claimed to cause less sedation?

What happens when a drug binds poorly to a receptor according to the text?

Why do nonsteroidal anti-inflammatory drugs sometimes cause discomfort and ulceration in the gastrointestinal mucosa?

What is the primary amine form of the carboxylic acid at physiological pH?

Why is adjusting the pH of phenytoin injection to 12 necessary?

What percentage of the drug is in the ionized form at pH 12?

Why is an alkaline solution with a pH of 12 generally not administered with other intravenous fluids?

What is the importance of understanding the 3D shape of a drug molecule, according to the text?

Why is the lock-and-key concept of drug-receptor interaction considered outdated?

What effect can drug-receptor association have on macromolecules, as mentioned in the text?

Why are slight structural variations in drugs significant, according to the text?

Acids are defined as proton acceptors and bases are defined as proton donors.

Water can act as an acid by donating a proton to a basic drug.

Ionized acids, like carboxylic acids, donate their protons forming ionized conjugate acids.

A drug's acid–base properties do not influence its biodistribution and partitioning characteristics.

During the initial trip through the liver, a significant proportion of a drug will be transported to the kidneys for excretion.

Lidocaine is an example of a drug that undergoes rapid metabolism during the first-pass effect.

The first-pass effect of lidocaine makes it practical to administer orally.

The understanding of the metabolic labile site on lidocaine led to the development of a similar drug called lidocainide.

Phenytoin injection must be adjusted to pH 10 to ensure complete ionization and maximize water solubility.

At pH 12, 99.0% of the drug phenytoin will be in the insoluble acid form.

A highly alkaline solution with a pH of 12 can be easily administered with other intravenous fluids buffered at pH 7.4.

Lowering the pH of phenytoin solution would result in the parent unionized phenytoin precipitating out of solution.

An increase of 1 pH unit from the pKa value will cause a BH+ acid to be 90.9% in the ionized form.

In the Henderson-Hasselbalch equation, when log [conjugate base] / [acid] = 1, the pH is equal to pKa.

Increasing the hydrogen ion concentration (decreasing the pH) will shift the equilibrium to the right for both HA acids and BH+ acids.

An increase of 2 pH units essentially shifts an HA acid to complete ionization (99%) and a BH+ acid to the nonionic conjugate base form (0.99%).

Why is Tropicamide buffered near pH 4 for eye drop administration?

Why are local anesthetic eye drops sometimes used along with Tropicamide eye drops?

In what pH range is indomethacin stabilized to prevent instability issues?

Why is only 50% of indomethacin in the water-soluble form when administered as a suspension at pH 4-5?

Why is the intravenous dosage form of indomethacin prepared as a sodium salt?