Pharmacology and Toxicology MCQ question and answer | Pharmacy MCQ question

Phenylketonuria (PKU) is an example of an inborn error of metabolism. Inborn errors of metabolism are genetic disorders that result from abnormalities in specific enzymes or metabolic pathways. In the case of PKU, individuals inherit a genetic mutation that leads to a lack or deficiency of the enzyme phenylalanine hydroxylase.

Phenylalanine hydroxylase is responsible for converting the amino acid phenylalanine into another amino acid called tyrosine. However, in individuals with PKU, the enzyme is either missing or not functioning properly, which leads to the accumulation of phenylalanine in the body.

The inherited lack of phenylalanine hydroxylase enzyme activity results in the inability to properly metabolize phenylalanine. Without treatment, high levels of phenylalanine can build up in the blood and tissues, leading to various health problems, including intellectual disabilities, developmental delays, and neurological issues.

Therefore, the correct answer is D. Inherited lack of an enzyme, as phenylketonuria is characterized by a genetic deficiency of the enzyme phenylalanine hydroxylase, which is essential for the normal metabolism of phenylalanine.

Digoxin is a medication used primarily in the treatment of heart failure and atrial arrhythmias.

One of its key effects is to decrease the heart rate by increasing vagal tone, which slows down the conduction through the atrioventricular (AV) node.

This leads to a reduction in the heart rate, which is particularly beneficial in conditions like atrial fibrillation where the heart rate is abnormally high.

Digoxin also increases the force of contraction of the heart muscle, making it more efficient at pumping blood.

Therefore, the correct effect of Digoxin on the heart rate is decrease.