Which phase of pharmacokinetics involves the movement of a drug from its site of administration to the bloodstream?

Choice A reason: Tinnitus is a rare side effect of Flexeril, which is a medication that relaxes the muscles and relieves pain and stiffness¹. Tinnitus is a ringing or buzzing sound in the ears that can be caused by various factors, such as ear infections, noise exposure, or certain medications. Flexeril does not affect the auditory system directly, but it can cause confusion or dizziness, which may worsen the perception of tinnitus.

Choice B reason: Drowsiness is the most common side effect of Flexeril, which is a medication that relaxes the muscles and relieves pain and stiffness¹. Drowsiness occurs because Flexeril has sedative and anticholinergic properties, which means that it blocks the action of acetylcholine, a neurotransmitter that regulates arousal and alertness. Flexeril can impair the mental and physical abilities, especially in elderly patients or those who take other medications that cause drowsiness¹. The nurse should educate the patient about the risk of drowsiness and advise them to avoid driving or operating machinery while taking Flexeril.

Choice C reason: Diarrhea is not a common side effect of Flexeril, which is a medication that relaxes the muscles and relieves pain and stiffness¹. Diarrhea is a condition that causes loose or watery stools, which can be caused by various factors, such as infections, food intolerance, or certain medications. Flexeril does not affect the gastrointestinal system directly, but it can cause dry mouth, nausea, or constipation, which may alter the bowel movements¹.

Choice D reason: Palpitations are not a common side effect of Flexeril, which is a medication that relaxes the muscles and relieves pain and stiffness¹. Palpitations are a sensation of rapid or irregular heartbeat, which can be caused by various factors, such as stress, anxiety, caffeine, or certain medications. Flexeril does not affect the cardiac system directly, but it can lower the blood pressure or interact with other medications that affect the heart rate, such as betablockers or antidepressants¹.

Choice A reason: “This medication should be taken after eating to reduce nausea.” is not a correct statement that demonstrates understanding about ondansetron. Ondansetron is a medication that prevents nausea and vomiting by blocking the action of serotonin, a chemical that stimulates the vomiting center in the brain. Ondansetron can be taken with or without food, and it does not affect the digestion or absorption of food. Ondansetron is usually taken before the start of chemotherapy, radiation, or surgery, which are the common causes of nausea and vomiting.

Choice B reason: “This medication should not be taken with starfruit.” is not a correct statement that demonstrates understanding about ondansetron. Ondansetron is a medication that prevents nausea and vomiting by blocking the action of serotonin, a chemical that stimulates the vomiting center in the brain. Ondansetron does not interact with starfruit, which is a tropical fruit that contains substances that can inhibit the enzyme CYP3A4, which is involved in the metabolism of many drugs. Ondansetron is mainly metabolized by another enzyme, CYP1A2, and it has a low potential for drug interactions¹.

Choice C reason: “This medication may make me tired and confused.” is a correct statement that demonstrates understanding about ondansetron. Ondansetron is a medication that prevents nausea and vomiting by blocking the action of serotonin, a chemical that stimulates the vomiting center in the brain. Ondansetron can also cross the blood brain barrier and affect other serotonin receptors in the brain, which are involved in regulating mood, cognition, and sleep. Ondansetron can cause side effects such as fatigue, drowsiness, headache, and confusion, which can impair the mental alertness and performance of the client. The client should be advised to avoid driving, operating machinery, or doing other tasks that require attention after taking ondansetron.

Choice D reason: “This medication may cause rebound nausea.” is not a correct statement that demonstrates understanding about ondansetron. Ondansetron is a medication that prevents nausea and vomiting by blocking the action of serotonin, a chemical that stimulates the vomiting center in the brain. Ondansetron does not cause rebound nausea, which is a condition of nausea that occurs after the discontinuation of a medication that suppresses nausea. Ondansetron is not a medication that suppresses nausea, but rather prevents it by blocking the stimulation of the vomiting center. Ondansetron does not cause dependence or withdrawal symptoms, and it can be stopped without causing rebound nausea.