Wk 9 Drug Therapy for Nausea and Vomiting

Nausea
- Definition: An unpleasant sensation of abdominal discomfort and an urge to vomit.
- Causes: Various factors including gastrointestinal issues, cardiac problems, neurological factors, pain, and pregnancy.
Vomiting (Emesis)
- Definition: Expulsion of stomach contents through the esophagus and out of the mouth and/or nose.
- Note: Vomiting is not necessarily preceded by nausea.
Antiemetic Drugs
- Purpose: Used to prevent and relieve nausea and vomiting (N/V).

Antiemetic
- Definition: A drug that blocks the hyperactive response of the chemoreceptor trigger zone (CTZ) to various stimuli, which produces non-beneficial nausea and vomiting.
Emetic
- Definition: An agent used to induce vomiting to rid the stomach of toxins or drugs.
- Note: No longer recommended in most cases.

Prochlorperazine (Compro)
- Mechanism: Depresses the CTZ to treat nausea and vomiting.
- Indications:
- Prevention of chemotherapy-induced emesis.
- Treats conditions like schizophrenia, psychosis, migraines, and hiccups.
Beers Criteria: Not appropriate for older adults and those under 18 years of age.
Available Forms and Timing:
- IM: Works in 10 minutes
- PO: Works in 30 minutes
- IV: Works in 30 minutes
- Rectal: Works in 60 minutes
Adverse Effects:
- Orthostatic hypotension
- Asthma exacerbation
- Anticholinergic effects
- Contraindicated in pregnancy and for older adults with dementia-related psychosis due to risk of death.

Mechanism: Blocks the action of acetylcholine, preventing stimulation of the CTZ.
Therapeutic Uses:
- Treats motion sickness, provides sedation, and relieves anxiety.
Notable Drugs:
- Vistaril
- Dimenhydrinate (Dramamine)
- Meclizine (Antivert)
Available Forms and Timing:
- PO only
- Dimenhydrinate works in 30 minutes
- Meclizine works in 1 hour
- Vistaril works in 30 minutes
Adverse Effects:
- Anticholinergic effects
- Prolonged QT interval
- Torsade de Pointes
Contraindications: Pregnancy.

Ondansetron (Zofran)
- Mechanism: Blocks 5-HT3 serotonin receptors in the CTZ and GI tract.
- Indications:
- Treatment of nausea and vomiting (N/V).
- Effective for chemotherapy/radiation therapy induced nausea and post-operative N/V.
Available Forms and Timing:
- PO: Works in 30 minutes
- IV: Works immediately
Adverse Effects:
- Diarrhea
- Headache (HA)
- Dizziness
- Pain at injection site
Contraindications: Patients on antidysrhythmic agents, and concern for prolonged QT interval and Torsade de Pointes.

Aprepitant (Emend)
- Mechanism: Blocks receptors in the brain that cause nausea.
- Indications:
- Effective for chemotherapy/radiation therapy induced nausea.
Available Forms and Timing:
- IV: Given 30-60 minutes prior to chemotherapy.
Synergistic Use:
- Often used with 5-HT3 receptor antagonists (serotonin blockers) and corticosteroids to treat acute N/V during chemotherapy.
Adverse Effects: CNS effects.
QSEN Safety Alert: Decreases INR which increases the risk of blood clots; INR checks recommended for 2 weeks post-use.

Ginger
- Side Effects: Increased bleeding risk with anticoagulants.
Peppermint
- Note: Avoid concurrent use with iron, antibiotics, seizure medications, cardiac or blood pressure medications, or medications to decrease stomach acid.
Acupuncture and Acupressure
- Acupressure wristbands may be helpful in managing nausea.

Assess complete history of nausea and vomiting, including precipitating factors.
Document current medications and note contraindications and potential drug interactions.
Common Adverse Effects:
- Drowsiness, dizziness, confusion, dry mouth, urinary retention, tachycardia.
- Advise patients about the risks associated with driving or performing hazardous tasks.
Note: Each drug also has specific miscellaneous adverse effects, necessitating checks before administration.
Caution against taking antiemetics with alcohol due to the risk of severe CNS depression.
Teach patients to change positions slowly to avoid hypotensive effects.

Adults: Ensure that CNS effects do not interfere with mobility or other activities.
Older Adults:
- More likely to develop adverse effects such as sedation, confusion, dizziness, fluid imbalance, and CV effects.
- Increased safety concerns for renal and hepatic function.

Assessment:
- Check for allergies, assess emesis (quantity, frequency, content), liver and renal lab results, BP, and for pregnancy or lactation.
Interventions:
- Use measures to prevent and minimize N/V.
- Administer antiemetics 30-60 minutes before chemotherapy, radiation, or travel.
- Avoid PO intake during N/V episodes.
- Record intake and output (I & O) and provide non-pharmaceutical remedies when possible.
- Offer appropriate education about the medications.
- Observe for subjective and objective signs of therapeutic effects.
Evaluation:
- Goals include relief of N/V, maintaining the ability to eat and retain food and fluids, and maintaining body weight.

Antiemetics are used to manage nausea and vomiting in cases where these actions are harmful to the patient.
Mechanism of Action: Antiemetics function by depressing the hyperactive vomiting reflex through local actions or alterations in CNS actions.
The selection of an antiemetic must be based on the causative factors behind the nausea and vomiting as well as the expected pharmacological actions of the drug.

Administration of Scopolamine:
- Consideration: Determine if the patient has a history of narrow-angle glaucoma.
Terminal Cancer Patient on Dronabinol:
- Purpose: Likely order to stimulate his appetite.
Pregnant Patient with Severe Morning Sickness:
- Anticipated drug choice: Ondansetron (Zofran) after other measures have failed.
Patient Taking Ginger:
- Important to inquire if the patient is using warfarin (Coumadin) due to increased bleeding risk.