Dosing and uses of Phenergan, Phenadoz (promethazine)
Adult dosage forms and strengths
tablet
- 12.5mg
- 25mg
- 50mg
suppository
- 12.5mg
- 25mg
- 50mg
injectable solution
- 25mg/mL
- 50 mg/mL
syrup
- 6.25mg/5mL
Allergic Conditions
PO/PR: 25 mg at bedtime or 12.5 mg before meals and at bedtime (dosage range, 6.25-12.5 mg q8hr)
IV/IM: 25 mg; may be repeated in 2 hours when necessary; switch to PO as soon as possible
Nausea & Vomiting
PO/PR: 12.5-25 mg q4-6hr PRn
IV/IM: 12.5-25 mg q4-6hr PRn
Motion Sickness
25 mg PO/PR 30-60 minutes before departure and q8-12hr PRN; on succeeding travel days, 25 mg PO/PR every morning and every evening
Preoperative Sedation
50 mg PO/PR on night before procedure or 25-50 mg IV/IM combined with reduced doses of analgesics and atropinelike drugs
Postoperative Sedation
25-50 mg IV/IM/PO/PR combined with reduced doses of analgesics and atropinelike drugs
Obstetric Sedation
25-50 mg IV/IM in early labor; may be increased to 25-75 mg q2-4hr after labor established; not to exceed two doses or up to 100 mg/day during labor
Pediatric dosage forms and strengths
tablet
- 12.5mg
- 25mg
- 50mg
suppository
- 12.5mg
- 25mg
- 50mg
injectable solution
- 25mg/mL
syrup
- 6.25mg/5mL
Allergic Conditions (Off-label)
<2 years old: Contraindicated
≥2 years old: 25 mg PO/PR at bedtime or 12.5 mg q6hr; alternatively, 6.25-12.5 mg PO/PR q8hr
Nausea & Vomiting
<2 years old: Contraindicated
≥2 years old: 0.25-1 mg/kg PO/PR q4-6hr PRN; not to exceed 25 mg
Motion Sickness
<2 years: Contraindicated
≥2 years: 12.5-25 mg PO/PR administered 30-60 minutes before departure and q8-12hr PRN or 0.5 mg/kg PO q12hr PRn
Succeeding days of travel: 12.5-25 mg twice daily (upon arising or before evening meals)
Sedation
<2 years: Contraindicated
≥2 years: 12.5-25 mg PO/IM/PR at bedtime
Preoperative Sedation
<2 years: Contraindicated
≥2 years: 1 mg/kg PO/PR with reduced dose of analgesic and appropriate dose of atropinelike drug
Postoperative Sedation
<2 years: Contraindicated
≥2 years: 12.5-25 mg with reduced dose of analgesic and appropriate dose of atropinelike drug
Phenergan, Phenadoz (promethazine) adverse (side) effects
Frequency not defined
Sedation
Confusion
Disorientation
Blurred vision
Hallucinations
Dystonias
Catatonic states
Euphoria
Excitation
Extrapyramidal symptoms
Tachycardia
Bradycardia
Leukopenia (rare)
Agranulocytosis (rare)
Obstructive jaundice
Photosensitivity
Dry mouth
Angioneurotic edema
Tardive dyskinesia
Urticaria
Xerostomia
Impotence
Urinary retention
Warnings
Black box warnings
IV administration can cause severe tissue injury, including burning, gangrene, or thrombophlebitis, necessitating fasciotomy, skin graft, or amputation
Severe tissue injury can occur from perivascular extravasation, unintentional intra-arterial injection, and intraneuronal or perineuronal infiltration
Deep IM injection is preferred method of administration
Intra-arterial and SC administration are contraindicated
25 mg/mL product may be administered by deep IM injection or IV infusion (at rate not to exceed 25 mg/min through flowing IV tubing)
Monitor for signs and symptoms of potential tissue injury including burning or pain at site of injection, phlebitis, swelling, and blistering
Discontinue IV infusion immediately if patient complains of pain during injection
Respiratory fatalities reported with use in children <2 years (use contraindicated); use lowest effective dose in children >2 years; avoid other drugs with respiratory depressant effects
Contraindications
Hypersensitivity
Newborn/premature infants <2 years old (risk of potentially fatal respiratory depression)
SC or intra-arterial administration
Coma
Treatment of lower respiratory tract symptoms, including asthma
Cautions
Use caution in asthma, hepatic impairment, peptic ulcer disease, respiratory impairment, bone marrow suppression, anaphylaxis in susceptible individuals
May impair ability to drive or perform hazardous tasks
May impair core body temperature regulation; caution when taking medications with anticholinergic effects, heat exposure, or strenuous exercise
Depresses hypothalamic thermoregulatory mechanism; exposure to extreme temperatures may cause hypo- or hyperthermia
May alter cardiac conduction (life-threatening arrhythmias reported)
Antiemetic effect may obscure toxicity of chemotherapeutic drugs
Monitor closely in patients with cardiovascular disease, hepatic impairment, Reye syndrome, or history of sleep apnea
Has anticholinergic effects; use with caution in patients with decreased gastrointestinal motility or obstructions (partial or comlete), urinary retention, urinary obstructions, xerostomia, BPH, or visual problems
May cause extrapyramidal symptoms including pseudoparkinsonism, acute dystonic reactions, tardive dyskinesia, and akathisia
Neuroleptic malignant syndrome reported with use; monitor for fever, muscle rigidity and/or autonomic instability, or mental status changes
May cause orthostatic hypotension; use caution in patients at risk of experiencing hypotensive episodes (cardiovascular disease, cerebrovascular disease, hypovolemia or taking medications that may predispose to bradycardia or hypotension)
May cause photosensitivity
Pyloroduodenal obstruction, stenosing peptic ulcer disease, bladder neck obstruction
Anticholinergic effects of promethazine may exacerbate condition in patients with narrow-angle glaucoma or myasthenia gravis
Pregnancy and lactation
Pregnancy category: C
Lactation: Not known whether drug crosses into breast milk; discontinue drug, or do not nurse
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Phenergan, Phenadoz (promethazine)
Mechanism of action
Phenothiazine derivative with antidopaminergic effect: Blocker of mesolimbic dopamine receptors and alpha-adrenergic receptors in brain
Antihistaminic effect: H1-receptor blocker
Absorption
Bioavailability: 25% (PO/PR)
Onset (antihistaminic effect): 3-5 min (IV); 20 min (IM/PO/PR)
Peak serum time: 6.7-8.6 hr (suppositories); 4.4 hr (syrup)
Duration: PO (motion sickness), 4-6 hr; IV (nausea and vomiting), 4-6 hr; up to 12 hr
Distribution
Protein bound: 93%
Vd: 98 L/kg (syrup); 17-277 L/kg (range)
Metabolism
Metabolized by hepatic P450 enzyme CYP2D6
Metabolites: Promethazine sulfoxide and glucuronides (inactive)
Elimination
Dialyzable: No
Half-life: 10 hr (IM); 9-16 hr (IV); 16-19 hr (syrup)
Excretion: Urine (major), feces (minor)
Administration
SC and intra-arterial injection contraindicated
IV Compatibilities
Solution: Compatible with most common solvents
Additive: Amikacin, ascorbic acid injection, chloroquine, hydromorphone, netilmicin, vitamins B and C
Syringe (partial list): Atropine, diphenhydramine, fentanyl, meperidine, morphine sulfate(?)
Y-site (partial list): Ciprofloxacin, cisplatin, cladribine, cyclophosphamide, cytarabine, fluconazole, gemcitabine, linezolid, teniposide
IV Incompatibilities
Additive: Aminophylline, chloramphenicol, chlorothiazide, floxacillin, furosemide, heparin, hydrocortisone sodium succinate, methohexital, penicillin G potassium (incompatible at promethazine 250 mg/L and penicillin 20 million units/L; may be compatible at lower concentrations), penicillin G sodium, pentobarbital, phenobarbital, thiopentaL
Syringe: Cefotetan, chloroquine, diatrizoate sodium 75%, diatrizoate meglumine/diatrizoate sodium, dimenhydrinate, heparin, iodipamide, iothalamate, ketorolac tromethamine, nalbuphine(?), pentobarbital, thiopentaL
Y-site: Aldesleukin, allopurinol, amphotericin B cholesteryl sulfate, cefazolin(?), cefepime, cefoperazone, cefotetan, ceftizoxime(?), doxorubicin liposomal, foscarnet, heparin(?), hydrocortisone sodium succinate(?), methotrexate, piperacillin/tazobactam, potassium chloride(?), vitamins B and C(?)
IV/IM Administration
Administer by deep IM injection or by injection into tubing of running IV infusion solution
IV: Concentration <25 mg/mL; infusion rate not to exceed 25 mg/min
Avoid extravasation
Storage
Store at controlled room temperature; protect from freezing
Protect from light
Discard if particulate matter formation or discoloration occurs
