Histantil , Phenergan
Classifications: antiemetic; antivertigo agent; phenothiazine; Therapeutic: antiemetic; antivertigo
Pregnancy Category: C
12.5 mg, 25 mg, 50 mg tablets; 6.25 mg/5 mL syrup; 12.5 mg, 25 mg, 50 mg suppositories; 25 mg/mL, 50 mg/mL injection
In common with other antihistamines, exerts anti-serotonin, anticholinergic, and local anesthetic action. Antiemetic action
thought to be due to depression of CTZ in medulla.
Long-acting derivative of phenothiazine with marked antihistamine activity and prominent sedative, amnesic, antiemetic,
and antimotion-sickness actions.
Symptomatic relief of various allergic conditions, to ameliorate and prevent reactions to blood and plasma, and in prophylaxis
and treatment of motion sickness, nausea, and vomiting. Preoperative, postoperative, and obstetric sedation and as adjunct
to analgesics for control of pain.
Hypersensitivity to phenothiazines; acute MI; angina, atrial fibrillation, atrial flutter, cardiac arrhythmias, cardiomyopathy
uncontrolled hypertension; MAOI therapy; comatose or severely depressed states; children with Reye's syndrome, hepatic encephalopathy,
hepatic diseases; acutely ill or dehydrated children; children <2 y; pregnancy (category C), lactation, newborn or premature
Impaired liver function; epilepsy; bone marrow depression; cardiovascular disease; peripheral vascular disease; asthma;
acute or chronic respiratory impairment (particularly in children); hypertension; narrow angle glaucoma; stenosing peptic
ulcer, pyloroduodenal obstruction; prostatic hypertrophy; bladder neck obstruction; older adult or debilitated patients;
children >2 y.
Route & Dosage
Adult: PO/PR 25 mg q12h prn
Child (>2 y): PO/PR 10.5 mg/kg/dose q12h prn (max: 25 mg/dose)
Adult: PO/PR/IM/IV 12.525 mg q46h prn
Child (>2 y): PO/PR/IM/IV 0.250.5 mg/kg q46h prn (max: 25 mg/dose)
Adult: PO/PR 12.5 mg q.i.d. or 25 mg h.s. IM/IV 25 mg, repeat in 2 h if necessary, switch to PO
Child (>2 y): PO 0.1 mg/kg q6h and 0.05 mg/kg at bedtime prn
Adult: PO/PR/IM/IV 2550 mg/dose
Child (>2 y): PO/PR/IM/IV 12.525 mg/dose (max: 50 mg)
- Give with food, milk, or a full glass of water may minimize GI distress.
- Tablets may be crushed and mixed with water or food before swallowing.
- Oral doses for allergy are generally prescribed before meals and on retiring or as single dose at bedtime.
- Give IM injection deep into large muscle mass. Aspirate carefully before injecting drug. Intraarterial injection can cause
arterial or arteriolar spasm, with resultant gangrene. Subcutaneous injection (also contraindicated) can cause chemical
irritation and necrosis. Rotate injection sites and observe daily.
PREPARE: Direct: ??The 25 mg/mL concentration may be given undiluted. Dilute the 50 mg/mL concentration in NS to yield no more than 25 mg/mL
(e.g., diluting the 50 mg/mL concentration in 4 mL yields 10 mg/mL).??Inspect parenteral drug before preparation. Discard if it is darkened or contains precipitate.
ADMINISTER: Direct: Give each 25 mg or fraction thereof over at least 1 min.
INCOMPATIBILITIES Solution/additive: Aminophylline, ampicillin, carbenicillin, cefazolin, cefotetan, ceftizoxime, chloramphenicol, chlordiazepoxide, chlorothiazide, dexamethasone, dimenhydrinate. furosemide, heparin, hydrocortisone, ketorolac, methicillin, methohexital, nalbuphine, nitrofurantoin, penicillin G sodium, pentobarbital, phenobarbital, thiopental. Y-site: Aldesleukin, allopurinol, amphotericin B cholesteryl complex, cefepime, cefmetazole, cefoperazone, cefotetan, doxorubicin liposome, foscarnet, furosemide, heparin, methotrexate, piperacillin/tazobactam, TPN.
- Store at 15°30° C (59°86° F) in tight, light-resistant container unless otherwise directed.
Adverse Effects (≥1%)Body as a Whole:
Deep sleep, coma, convulsions, cardiorespiratory symptoms
, extrapyramidal reactions, nightmares (in children), CNS
abnormal movements. Respiratory:
Irregular respirations, respiratory depression, apnea. CNS:
confusion, dizziness, disturbed coordination, restlessness, tremors. CV:
Transient mild hypotension or hypertension. GI:
Anorexia, nausea, vomiting, constipation
. Hematologic: Leukopenia
, agranulocytosis. Special Senses: Blurred vision, dry mouth,
nose, or throat. Skin:
Diagnostic Test Interference
May interfere with blood grouping in ABO system and may produce false results with urinary pregnancy tests (Gravindex, false-positive; Prepurex and Dap tests, false-negative). Promethazine can cause significant alterations of flare response in intradermal allergen tests if performed within 4 d of patient receiving promethazine.
and other cns depressants
add to CNS depression
and anticholinergic effects.
Readily from GI tract. Onset:
20 min PO/PR/IM; 5 min IV
28 h. Distribution:
Crosses placenta. Metabolism:
In liver (CYP2D6, 2B6). Elimination:
Slowly in urine and feces.
Assessment & Drug Effects
- Supervise ambulation. Promethazine sometimes produces marked sedation and dizziness.
- Be aware that antiemetic action may mask symptoms of unrecognized disease and signs of drug overdosage as well as dizziness,
vertigo, or tinnitus associated with toxic doses of aspirin or other ototoxic drugs.
- Patients in pain may develop involuntary (athetoid) movements of upper extremities following parenteral administration. These
symptoms usually disappear after pain is controlled.
- Monitor respiratory function in patients with respiratory problems, particularly children. Drug may suppress cough reflex
and cause thickening of bronchial secretions.
Patient & Family Education
- For motion sickness: Take initial dose 3060 min before anticipated travel and repeat at 812 h intervals if necessary.
For duration of journey, repeat dose on arising and again at evening meal.
- Do not drive or engage in other potentially hazardous activities requiring mental alertness and normal reaction time until
response to drug is known.
- Avoid sunlamps or prolonged exposure to sunlight. Use sunscreen lotion during initial drug therapy.
- Do not take OTC medications without physician's approval.
- Avoid alcohol and other CNS depressants.
- Relieve dry mouth by frequent rinses with water or by increasing noncaloric fluid intake (if allowed), chewing sugarless
gum, or sucking hard candy. If these measures fail, add a saliva substitute (e.g., Moi-Stir, Orex, Xero-Lube).