Medications

Question 1

A 30-year-old female is planning a trip to Australia and is concerned about motion sickness. Which one of the following medications is most effective for preventing this problem? (check one)
Dimenhydrinate (Dramamine)
Diphenhydramine (Benadryl)
Meclizine (Antivert)
Promethazine
Scopolamine

Answer 1

Scopolamine

Motion sickness is a syndrome that includes nausea and other symptoms, including vague subtle symptoms of stomach awareness, malaise, fatigue, and irritability. The most effective medication is scopolamine; transdermal scopolamine is more effective than oral scopolamine.

Question 2

An 80-year-old male with well-controlled hypertension undergoes surgery to repair a hip fracture. He had coronary artery stenting 6 years ago and is asymptomatic. His current medications include lisinopril (Zestril), atorvastatin (Lipitor), and low-dose aspirin. He also takes chronic gabapentin (Neurontin) for postherpetic neuralgia, which is continued postoperatively. Multimodal analgesia is used, including intravenous morphine as needed after surgery.

In the postoperative period, this patient would be at greatest risk for which one of the following? (check one)
Gabapentin withdrawal symptoms
Heart failure
Respiratory depression
Restless legs syndrome
Seizure

Answer 2

Respiratory depression

In the postoperative period, this patient would be at greatest risk for respiratory depression. In 2019 the FDA issued a Drug Safety Communication about the risk of serious breathing difficulties that may occur with the use of gabapentin or pregabalin in patients who have respiratory risk factors. The FDA found that respiratory depression can occur when opioids or other medications that depress the central nervous system (CNS) are administered to patients who are taking gabapentinoids or to those with underlying respiratory impairments such as COPD or age-related loss of function. This patient is taking chronic gabapentin, is elderly, and is being prescribed the opioid morphine as needed for postoperative pain.

Gabapentinoids, including gabapentin, are being increasingly used for conditions such as seizures, nerve pain, and restless legs syndrome. Misuse is also increasing. They are often combined with other CNS depressants such as opioids, anti-anxiety medications, antidepressants, and antihistamines, thus increasing the risk of respiratory depression.

Since gabapentin is continued after surgery in this patient, withdrawal symptoms would not be likely. While the patient should be monitored for heart failure, his cardiac status is stable on the current regimen. This patient would not be at increased risk for restless legs syndrome or seizures due to continued management with gabapentin.

Question 3

Which one of the following juices can greatly increase the blood level of a statin? (check one)
Apple
Grapefruit
Orange
Pineapple
Tomato

Answer 3

Grapefruit

Ingestion of grapefruit juice can increase absorption and serum levels of statins, leading to an increased risk of muscle injury. The mechanism for this is believed to be the cytochrome p-450 pathway. Starfruit juice and pomegranate juice can have a similar effect. These juices contain an irreversible inhibitor of intestinal CYP3A4, and increase the bioavailability of atorvastatin, lovastatin, and simvastatin. Rosuvastatin and fluvastatin utilize the CYP2C9 system for metabolism, so the effect on these drugs is minimal.

Grapefruit juice reduces CYP3A4 activity by 50% within 4 hours of ingestion, and activity is reduced by 30% for as long as 24 hours after ingestion. Several studies document that consuming 600 mL of double-strength juice for 3 days produces a more than tenfold increase in the area under the curve for simvastatin and lovastatin, but only a 250% increase in atorvastatin.