Promethazine HCl (Phenergan) Drug Study

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Generic Name: promethazine HCl

Brand Name: Phenergan

Action: anti-emetics, antihistamines, sedative/hypnotics

Mechanism of Action of Phenergam

Selectively blocks H1 receptors, diminishing the effects of histamine on cells of the upper respiratory tract and eyes and decreasing the sneezing, mucus production, itching and tearing that accompany allergic reactions. blocks cholinergic receptors in the vomiting center that are believed to mediate the nausea and vomitting caused by gastric irritation.

Indication of Promethazine

• Preoperative sedation, treatment and prevention of nausea and vomiting, adjunct to anesthesia and analgesia.

Contraindication of Promethazine

• Hypersensitivity, comatose patient, prostatic hypertrophy, bladder neck obstruction, narrow angle glaucoma

Dosage of Promethazine

• 25-50 mg (sedation); 10-25mg q 4hr as needed (anti-emetic) (1amp)

Side Effects of Promethazine

• CNS: neuroleptic malignant syndrome, confusion, disorientation, sedation, dizziness, extrapyramidal reaction, fatigue, insomnia, nervousness;
• EENT: blurred vision, diplopia, tinnitus;
• CV: bradycardia, hypertension, hypotension, tachycardia;
• GI: constipation, drug-induced hepatitis, dry mouth;
• Derm: photosensitivity, rashes;
• Hemat: blood dyscrasias

Nursing Considerations of Promethazine

• Monitor BP, pulse and respiratory rate frequently.
• Assess level of sedation after administration.
• Assess patient for nausea and vomiting before and after administration.
• Administer each 25mg slowly over at least 1 hr.
• Do not give rectal supp or tabs to children younger than 2 years old because of risk of fetal respiratory depressions
• Give IM injections deep into muscle
• Do not administer SQ, tissue necrosis may occur
• Arteriospasms and gangrene of artery may occur when administered intra-arterially.
• Reduce dosage of barbiturates given concurrently within promethazine by least half.