Medication Overview

Sominex is an over-the-counter medication primarily used to induce sleep. It contains the active ingredient diphenhydramine hydrochloride, an antihistamine known for its sedative properties. It is commonly taken by individuals who experience occasional bouts of insomnia or difficulty falling asleep. Sominex is manufactured in various forms, including tablets and capsules, allowing for flexible administration routes for users.

Active Ingredient

The primary active component of Sominex is diphenhydramine hydrochloride. This chemical compound belongs to the ethanolamine class of antihistamines. It works by blocking histamine receptors in the brain, creating drowsiness as a side effect. The typical dosage found in Sominex is 25-50 mg per tablet or capsule. Diphenhydramine hydrochloride is also used for its anticholinergic properties, aiding in the reduction of symptoms related to allergies and the common cold.

Mechanism of Action

Diphenhydramine hydrochloride acts by infiltrating the central nervous system and antagonizing H1 histamine receptors. This reduces histamine-mediated symptoms, such as sneezing and itching. The central nervous system depression is responsible for its sedative effect. The anticholinergic activity contributes to the drying of nasal and bronchial secretions, beneficial in managing cold symptoms. The medication reaches its peak plasma concentration within two hours of oral administration.

Dosage and Administration

Sominex is typically taken 30 minutes before bedtime. The usual adult dosage is one or two 25 mg tablets or capsules, depending on the severity of sleeplessness. It is crucial to follow dosing guidelines to avoid overmedication. For elderly patients, lower dosages might be recommended due to increased susceptibility to side effects. Both forms—tablets and capsules—should be swallowed whole with a full glass of water. The medication should not be crushed or chewed.

Pharmacokinetics

After oral administration, diphenhydramine hydrochloride is absorbed rapidly from the gastrointestinal tract. It has a plasma half-life of approximately 4-9 hours. The medication is widely distributed throughout the body, including the CNS. It is primarily metabolized in the liver through processes like N-demethylation and N-oxidation. Excretion mainly occurs via renal routes, with small amounts excreted unchanged in urine. The pharmacokinetic profiles show variations among individuals based on factors like age, organ function, and co-administered substances.

Potential Side Effects

Possible adverse effects of Sominex include drowsiness, dizziness, constipation, blurred vision, and dry mouth. Less common but serious side effects comprise tachycardia, urinary retention, and confusion, particularly in the elderly. Dermatological reactions, such as rash or photosensitivity, have been reported but are rare. Long-term use or overuse can lead to tolerance and dependence. Persistent side effects or allergic reactions should prompt discontinuation and consultation with a healthcare provider.

Drug Interactions

Sominex may interact with various medications, potentially altering its effectiveness or increasing side effects. Concomitant use of other CNS depressants, like alcohol or sedatives, can compound sedative effects, increasing the risk of severe drowsiness. Monoamine oxidase inhibitors (MAOIs) may prolong and intensify anticholinergic effects. Selective serotonin reuptake inhibitors (SSRIs), antipsychotics, and other antihistamines can interfere with diphenhydramine metabolism, requiring adjusted dosages. Consult with a healthcare provider to manage potential interactions effectively.

Contraindications

Sominex is contraindicated for individuals with known hypersensitivity to diphenhydramine or any of its inactive ingredients. It should be avoided in individuals with narrow-angle glaucoma, severe cardiovascular disorders, stenosing peptic ulcer, and symptomatic prostatic hypertrophy. It is also contraindicated for use in newborns and premature infants. Concomitant use with other antihistamines or sedative agents requires caution. Patients with chronic obstructive pulmonary disease (COPD) should refrain from taking this medication without professional advice.

Use in Special Populations

Caution is advised when administering Sominex to pediatric populations, and professional guidance is necessary, as safety and efficacy have not been well-established. For pregnant or breastfeeding women, use should only proceed if clearly needed and prescribed by a healthcare provider, given potential effects on the fetus or infant. In elderly populations, the sedative and anticholinergic effects may be more pronounced, necessitating close monitoring and possible dosage adjustments. Patients with hepatic or renal impairment may require modified dosing due to altered pharmacokinetics.

Storage and Handling

Sominex should be stored at room temperature, away from direct light and moisture. It is crucial to keep it out of reach of children and pets. The packaging should remain intact to maintain tablet and capsule integrity. Disposal of expired or unused medication should follow local regulations, typically involving medication take-back programs or consulting a pharmacist for recommendations. Proper storage ensures the medication’s efficacy and safety throughout its shelf life.

Clinical Efficacy Studies

Various clinical studies have demonstrated the efficacy of diphenhydramine hydrochloride in promoting sleep onset and duration. Randomized controlled trials indicate that Sominex significantly reduces sleep latency compared to a placebo. The medication’s effectiveness in mitigating mild to moderate insomnia has been validated across diverse demographic groups. Long-term studies, however, underscore the risk of tolerance and diminished efficacy over time, suggesting the necessity for intermittent or short-term use.