DIMENHYDRINATE
INDICATION AND DOSAGE OF DIMENHYDRINATE
What It Is
Dimenhydrinate is a commonly used medication primarily for its antiemetic and antihistamine properties. It is widely recognized for its effectiveness in treating symptoms associated with motion sickness and nausea. Structurally, dimenhydrinate is a combination of diphenhydramine, an antihistamine, and 8-chlorotheophylline, a stimulant. This combination enhances its effectiveness in reducing nausea and vomiting compared to its individual components.
Dosage Forms and Strengths
Dimenhydrinate is available in several dosage forms, including:
- Tablets: Commonly available in 50 mg strengths.
- Chewable Tablets: Typically 50 mg each, designed for ease of consumption.
- Capsules: Often found in 50 mg strength.
- Liquid: Available in a 12.5 mg/5 ml concentration.
- Suppositories: Less common but available in 25 mg strength.
Brand and Generic Names
Dimenhydrinate is marketed under several brand names, including:
- Dramamine: The most well-known brand, widely available over the counter.
- Dramamine II: A specific formulation of Dramamine with different indications.
- Dramamine Less Drowsy: Contains meclizine, a related but different antihistamine.
The generic name for this medication is dimenhydrinate, and it is often available as a generic drug under this name.
Indications for Use
Dimenhydrinate is primarily indicated for:
- Motion Sickness: To prevent and treat nausea, vomiting, and dizziness caused by motion sickness.
- Nausea and Vomiting: Associated with various conditions, including postoperative nausea and vomiting.
- Vertigo: To alleviate symptoms of vertigo and dizziness.
Mechanism of Action
Dimenhydrinate works by blocking histamine H1 receptors in the body. Histamine is a chemical involved in allergic reactions and the regulation of the vomiting center in the brain. By antagonizing these receptors, dimenhydrinate reduces the feeling of nausea and prevents the vomiting reflex. Additionally, 8-chlorotheophylline in dimenhydrinate acts as a mild stimulant, counteracting some of the drowsiness caused by diphenhydramine.
Administration and Dosage
The dosage of dimenhydrinate varies based on the age of the patient and the condition being treated. Typical dosages are:
- Adults: 50 to 100 mg taken every 4 to 6 hours as needed, with a maximum daily dose of 400 mg.
- Children: The dosage is generally lower and should be adjusted according to age and weight, typically around 25 to 50 mg every 6 to 8 hours, not exceeding 150 mg per day.
Dimenhydrinate should be taken with food or a full glass of water to minimize stomach upset. For motion sickness, it is recommended to take the medication 30 to 60 minutes before traveling.
Side Effects and Precautions
Common side effects of dimenhydrinate include:
- Drowsiness: The most frequent side effect, which can impair the ability to operate vehicles or machinery.
- Dizziness: Some users may experience dizziness or light-headedness.
- Dry Mouth: An anticholinergic effect, leading to a dry mouth sensation.
- Constipation: Reduced gastrointestinal motility can cause constipation.
Less common but more serious side effects may include:
- Severe Allergic Reactions: Rare, but may include symptoms like rash, itching, and swelling.
- Confusion: Particularly in elderly patients, dimenhydrinate can cause confusion or agitation.
Precautions:
- Elderly Patients: They are more susceptible to the sedative effects and should use dimenhydrinate with caution.
- Pregnancy: It falls under Category B, indicating no evidence of harm in animal studies, but should be used only if necessary and prescribed by a healthcare provider.
- Interactions: Dimenhydrinate may interact with other central nervous system depressants, enhancing drowsiness and sedation.
Conclusion
Dimenhydrinate remains a valuable medication for managing motion sickness and associated symptoms of nausea and vomiting. Its combination of antihistamine and stimulant properties provides effective relief for many patients. While generally safe and well-tolerated, users must be mindful of potential side effects, especially drowsiness, and take necessary precautions to avoid impairment. As with any medication, appropriate use according to the prescribed dosage and guidance from a healthcare provider ensures optimal benefits while minimizing risks.