In short
Cyclizine hydrochloride is a medication being studied in clinical trials for its effectiveness in preventing and treating postoperative nausea and vomiting (PONV). This common but distressing side effect affects many patients after surgery, particularly those undergoing bariatric surgery or cesarean sections with spinal anesthesia. Recent clinical trials are comparing cyclizine to other antiemetic medications like metoclopramide and dexamethasone to determine which provides better outcomes for patients. These studies examine how cyclizine affects gastric residual volume and its effectiveness in preventing nausea and vomiting, which could lead to improved recovery and patient satisfaction after surgery.
Key points
- Cyclizine hydrochloride is being studied in clinical trials as an antiemetic medication to prevent postoperative nausea and vomiting. Research is comparing 50 mg of intravenous cyclizine against metoclopramide in bariatric surgery patients and against dexamethasone in cesarean section patients. The medication works primarily as a histamine H1-receptor antagonist with additional effects on dopamine receptors and vestibular nuclei. Key outcomes being measured include changes in gastric residual volume and the incidence of nausea and vomiting in the hours following surgery. These trials aim to determine the most effective antiemetic strategy for high-risk surgical procedures where PONV is particularly common and problematic.
At a glance
- Drug Name
- Cyclizine Hydrochloride
- Drug Classification
- Antihistamine (H1-receptor antagonist), also affects dopamine and cholinergic receptors
- Typical Dosage
- 50 mg intravenously
- Clinical Trial Applications
- Bariatric surgery, Cesarean section with spinal anesthesia
- Comparison Medications
- Metoclopramide (10 mg) in bariatric surgery; Dexamethasone (8 mg) in cesarean sections
- Primary Outcomes Measured
- Gastric residual volume, Incidence of postoperative nausea and vomiting
- Measurement Timeframes
- 1 hour post-administration (bariatric); 30 minutes, 3 hours, and 6 hours post-intervention (cesarean)
- Mechanism of Action
- Blocks histamine receptors, affects dopamine receptors, has anticholinergic properties, inhibits vestibular nuclei function
- Target Condition
- Postoperative nausea and vomiting (PONV)
What is Cyclizine Hydrochloride?
Cyclizine Hydrochloride is a medication primarily used to prevent and treat nausea and vomiting. It belongs to a class of drugs known as antihistamines, specifically H1-receptor antagonists. Cyclizine is a piperazine derivative that works by blocking certain receptors in the body that trigger nausea and vomiting. This medication is commonly used in various medical settings where patients might experience nausea and vomiting, such as after surgery or during motion sickness.
How Cyclizine Works
Cyclizine works through several mechanisms in the body to prevent nausea and vomiting:
- It primarily acts as a histamine H1-receptor antagonist, blocking the action of histamine, which can trigger nausea
- It has some effect on dopamine D2 receptors
- It affects cholinergic receptors in the body
- It inhibits the integrative function of the vestibular nuclei (parts of the brain involved in balance and spatial orientation)
Although researchers haven't fully explained all the ways cyclizine prevents nausea and vomiting, its central anticholinergic properties (blocking certain nerve signals) are partially responsible for its effectiveness. The medication also has central nervous system depressant and local anesthetic effects. Once in the body, cyclizine is metabolized (broken down) to its derivative called norcyclizine, which has little antihistamine activity compared to cyclizine itself.
Medical Uses of Cyclizine
Cyclizine is prescribed for several conditions involving nausea and vomiting:
- Postoperative nausea and vomiting (PONV) - preventing sickness after surgery
- Motion sickness - preventing or treating nausea related to travel
- Drug-induced nausea - treating nausea caused by other medications
- Vertigo - managing dizziness in diseases affecting the vestibular apparatus (the balance system in your inner ear)
Cyclizine can be administered by mouth (orally) or given as an injection (parenterally), depending on the patient's condition and needs.
Cyclizine in Bariatric Surgery
Bariatric surgery (weight loss surgery) patients often experience significant postoperative nausea and vomiting. This can delay recovery by preventing patients from eating normally and moving around after surgery, which may lead to longer hospital stays.
Several factors contribute to the high rate of nausea and vomiting after bariatric surgery:
- Obesity itself
- Presence of hiatal hernia (when part of the stomach pushes up into the chest)
- Direct stomach irritation from surgical trauma
- Presence of blood and secretions in the stomach
- Abdominal insufflation (inflation of the abdomen with gas during surgery)
- Surgical duration exceeding 1 hour
- The use of opioid pain medications
Recent research has been comparing the effectiveness of Cyclizine versus other medications such as Metoclopramide in reducing gastric residual volume (GRV) in bariatric surgery patients. GRV refers to the amount of fluid remaining in the stomach and is considered a predictor of postoperative nausea and vomiting. By measuring GRV using ultrasound, doctors can assess how well these medications are working to improve stomach emptying.
Cyclizine for Cesarean Section Patients
Cyclizine is also being studied for use in patients undergoing cesarean section (C-section) who receive intrathecal morphine (morphine injected into the spinal fluid) for pain control. This type of pain control can frequently cause nausea and vomiting as side effects.
In this context, cyclizine (50 mg given intravenously) is being compared with dexamethasone (a steroid medication) for preventing nausea and vomiting. The medication is typically administered within 1-2 minutes after the umbilical cord is clamped during the C-section procedure to ensure it doesn't affect the baby.
Comparison with Other Medications
Cyclizine is considered a "second-line" anti-nausea medication in some treatment protocols. This means it may be used when first-line medications aren't sufficient or appropriate.
First-line anti-nausea medications typically include:
- Serotonin antagonists (like ondansetron)
- Corticosteroids (like dexamethasone)
- Dopamine antagonists (like droperidol)
These medications work by different mechanisms and can reduce the risk of nausea and vomiting by about 25% each. They can be used in combination for better effects.
In bariatric surgery, cyclizine is being compared with metoclopramide, which is a dopamine receptor antagonist that also has effects on bowel transit time and serotonin receptors at high doses.
How Cyclizine is Administered
Cyclizine can be administered in several ways:
- Oral form - taken by mouth as tablets
- Intravenous (IV) form - injected directly into a vein
In the clinical trials described, cyclizine was administered intravenously at a dose of 50 mg. For bariatric surgery patients, it was delivered in a 10 mL syringe, while for cesarean section patients, it was given within 1-2 minutes after the umbilical cord was clamped.
Risk Factors for Nausea and Vomiting
Understanding the risk factors for postoperative nausea and vomiting can help you know why cyclizine might be prescribed. These risk factors fall into two main categories: