Pharmparty Quiz

The intrinsic drug clearance can be affected by various factors such as smoking, dietary considerations, age, and genetics. Smoking can alter the metabolism of drugs and decrease their clearance rate. Dietary considerations, such as the consumption of certain foods or beverages, can also affect drug clearance by interacting with the drug or its metabolism. Age can impact drug clearance due to changes in liver and kidney function. Genetics plays a role in drug metabolism, as individuals may have variations in enzymes responsible for drug clearance. Therefore, all of the mentioned factors can potentially change intrinsic drug clearance.

The volume of distribution is a pharmacokinetic parameter that determines the extent of drug distribution in the body. It is influenced by various factors including the patient's gender, age, disease state, and body composition. Gender differences can affect drug distribution due to variations in body size and composition. Age can impact the volume of distribution as it affects body composition and organ function. Disease state can alter the volume of distribution by affecting organ function and blood flow. Lastly, body composition, such as muscle mass and adipose tissue, can influence drug distribution. Therefore, all of the above factors can influence the volume of distribution.

The explanation for the correct answer, which is "first order," is that the absorption rate is directly proportional to the drug concentration dissolved in the gastrointestinal tract. This means that as the drug concentration increases, the absorption rate also increases. In a first-order process, the rate of absorption is dependent on the concentration of the drug, making it the most suitable explanation.

CYP450 (oxidation)
alcohol and aldehyde oxidation
azo and nitro reduction
hydrolysis

When the pH is above the pKa value, it means that the solution is more basic. In this case, a weak acid would tend to ionize less, as it prefers to remain in its non-ionized form. On the other hand, a weak base would be more likely to accept protons and ionize more in a basic solution. Therefore, the correct answer is weak acid.

An increase in the synthesis rate of cytochrome P450 enzymes can lead to an increase in the amount of these enzymes. This can occur when the body needs to metabolize drugs or other substances at a faster rate. By increasing the synthesis of cytochrome P450 enzymes, the body can produce more of these enzymes to help break down and eliminate the drugs from the system. This increased synthesis can be a response to higher drug concentrations or to the presence of certain substances that induce the production of cytochrome P450 enzymes.

The given information states that the compound is a weak organic acid with a pKa of 6.5. The pKa value represents the acidity of the compound, and a lower pKa indicates a stronger acid. Since the pH of the solution is 7.5, which is higher than the pKa, the compound will be mostly ionized. Therefore, the highest percentage of ionization would be 90%, as indicated in the answer.

Phase II conjugates are formed when a polar functional group, such as a sulfate or glucuronide, is added to a drug or toxin during metabolism. These conjugates are relatively nonpolar, which allows them to be easily transported across cell membranes. They are also generally biologically active, meaning they can still exert their effects on target molecules. However, one of the main characteristics of phase II conjugates is that they are rapidly excreted in the urine. This is because the addition of a polar group increases their water solubility, making them more easily eliminated from the body through the kidneys.

The kidney is the most important organ for unchanged drug/drug metabolite elimination. The kidneys filter the blood and remove waste products, including drugs and their metabolites, through urine. This process is known as renal excretion. The liver also plays a role in drug metabolism and elimination, but it primarily metabolizes drugs into inactive forms rather than eliminating them unchanged. The lungs primarily eliminate volatile substances, such as gases, but they have a limited role in drug elimination. Therefore, the kidney is the most crucial organ for eliminating drugs and their metabolites from the body.

Weak bases are usually excreted faster in acidic urine because in an acidic environment, weak bases tend to become ionized and therefore more water-soluble. This increased solubility allows them to be easily filtered by the kidneys and excreted in urine. On the other hand, weak acids are excreted slower in alkaline urine because the alkaline environment causes them to become more ionized, making them less water-soluble and less likely to be filtered by the kidneys.

recall that the pH would have to be 6.4 for 1/2 of the molecules to accept a proton and become charged. At pH 8.4 (intestine), the hydrogen ion concentration is too low for this weak base to accept a proton and become charged.

A weak base at alkaline pH can exist in both charged and uncharged forms. When the pH is alkaline, the weak base may accept a proton, becoming charged. However, it can also remain uncharged if it does not accept a proton. The fact that it is relatively lipid-soluble suggests that it can easily cross cell membranes, which is characteristic of uncharged molecules. Therefore, the correct answer is both.

The dramatic decrease in systemic availability of a drug following oral administration is most likely due to extreme drug instability at stomach pH. This means that the drug is not able to withstand the acidic environment of the stomach, causing it to degrade or become inactive before it can be absorbed into the bloodstream. As a result, the drug's availability for systemic circulation is significantly reduced.

At alkaline pH, weak acid drugs become ionized and less lipid-soluble. However, weak base drugs become non-ionized and more lipid-soluble. Therefore, more of the weak acid drug will be in the lipid-soluble form at alkaline pH. This is because the weak acid drug will be mostly ionized and less lipid-soluble at acid pH. The statement "A & C" is incorrect because weak base drugs will be in the lipid-soluble form at alkaline pH, not weak acid drugs. The statement "B & C" is incorrect because weak acid drugs will be less lipid-soluble at acid pH.