Dosing and uses of Zantac, Zantac 150 Maximum Strength (ranitidine)
Adult dosage forms and strengths
injection solution
- 25mg/mL
syrup
- 15mg/mL
tablet
- 75mg
- 150mg
- 300mg
capsule
- 150mg
- 300mg
Gastroesophageal Reflux Disease
150 mg PO q12hr or 50 mg IM/IV q6-8hr
Gastric Ulcer, Benign
Treatment: 150 mg PO q12hr or 300 mg PO at bedtime
Maintenance of healing: 150 mg PO at bedtime
Erosive Esophagitis
Treatment: 150 mg PO q6hr or 50 mg IM/IV q6-8hr intermitent bolus or infusion; alternatively, 6.25 mg/hr IV by continuous infusion
Maintenance of healing: 150 mg PO q12hr
Hypersecretory Conditions
150 mg PO q12hr; up to 6 g/day used
Parenteral: 50 mg (2 mL) IM or intermitent IV bolus or infusion q6-8hr; not to exceed 400 mg/day; alternatively, 6.25 mg/hr continuous infusion
Dosing considerations
- More frequent doses may be necessary; individualize dosage, and continue as long as indicated; dosages up to 6 g/day have been used for severe disease
- Zollinger-Ellison syndrome: Start IV infusion at 1 mg/kg/hr, then adjust upward in 0.5 mg/kg/hr increments according to gastric acid output (not to exceed 2.5 mg/kg/hr or 220 mg/hr)
Stress Ulcer Prophylaxis (Off-label)
150 mg PO or NG q12hr
50 mg (2 mL) IM or intermitent IV bolus or infusion q6-8hr; not to exceed 400 mg/day; alternatively, 6.25 mg/hr continuous infusion
Dosing Modifications
Renal impairment (CrCl <50 mL/min): 50 mg IV/IM q18-24hr or 150 mg PO once daily
Hepatic impairment: Dosage adjustment not necessary
Pediatric dosage forms and strengths
injection solution
- 25mg/mL
syrup
- 15mg/mL
tablet/capsule
- 75mg
- 150mg
- 300mg
capsule
- 150mg
- 300mg
Active Duodenal/Gastric Ulcer
Treatment: 4-8 mg/kg PO q12hr; not to exceed 300 mg/day
Maintenance: 2-4 mg/kg PO once daily; not to exceed 150 mg/day
Parenteral: 2-4 mg/kg/day IV divided q6-8hr; not to exceed 50 mg/dose or 200 mg/day
Gastroesophageal Reflux Disease
1 month - 16 years
5-10 mg/kg/day PO divided q12hr; not to exceed 300 mg/day
Parenteral (Off-label): 2-4 mg/kg/day IV divided q6-8hr; not to exceed 50 mg/dose or 200 mg/day; alternatively, infusion at 1mg/kg/dose once followed by continuous infusion of 0.08-0.17 mg/kg/hr or 2-4 mg/kg/day
Erosive Esophagitis
1 month - 16 years
5-10 mg/kg/day PO divided q12hr; not to exceed 300 mg/day
Parenteral (Off-label): 2-4 mg/kg/day IV divided q6-8hr; not to exceed 200 mg/day; alternatively, 1mg/kg/dose once followed by continuous infusion of 0.08-0.17 mg/kg/hr or 2-4 mg/kg/day
Neonates (Off-label)
Term Neonates (<29 days)
- 2-4 mg/kg/day PO divided q8-12hr or 2 mg/kg/day IV divided q8hr
- Prophylaxis against dexamethasone associated ulceration: 0.031-1.25 mg/kg/hr during dexamethasone therapy to maintain gastric pH >4
- Prophylaxis against stress ulceration: 2 mg/kg q12hr or 1.5 mg/kg IV q8hr; alternativley, 2 mg/kg over 10 min, followed by continuous infusion of 0.083 mg/kg/hr
Zantac, Zantac 150 Maximum Strength (ranitidine) adverse (side) effects
1-10%
Headache (3%)
<1%
Abdominal pain
Agitation
Alopecia
Confusion
Constipation
Diarrhea
Dizziness
Hypersensitivity reaction
Nausea
Vomiting
Frequency not defined
Anemia
Necrotizing enterocolitis in fetus or newborn
Pancreatitis (rare)
Thrombocytopenia (rare)
Pancytopenia (rare)
Agranulocytosis (rare)
Acquired immune hemolytic anemia (rare)
Arthralgia (rare)
Myalgia (rare)
Warnings
Contraindications
Hypersensitivity to ranitidine or components of the formulation
Cautions
If gastroesophageal reflux disease does not respond adequately in 6-8 weeks, do not increase dosage; prescribe proton pump inhibitor instead
Prolonged treatment may lead to B12 malabsorption and subsequent vitamin B12 deficiency; degree of deficiency is dose-related and association stronger in females and younger in age (<30 years)
Use caution in renal impairment; adjust dosage
Use caution in hepatic impairment
Elevation of ALT levels reported with higher doses (≥100 mg) or prolonged IV therapy (≥5 days); monitor for ALT levels for the remainder of treatment
Avoid in patients with acute porphyria; may precipitate attack
Symptom relieve does not rule out presence of gastric malignancy
Reversible comfusional state reported with use (linked to age >50 years and renal or hepatic impairment); clears within 3-4 days after discontinuation
Pregnancy and lactation
Pregnancy category: B
Lactation: Drug crosses into breast milk; discontinue drug, use caution
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 Zantac, Zantac 150 Maximum Strength (ranitidine)
Mechanism of action
H2-receptor antagonist; blocks H2 receptors of gastric parietal cells, leading to inhibition of gastric secretions
Absorption
Bioavailability: 50% (PO); 90-100% (IM)
Onset: 1 hr (IV/PO)
Duration: 4-5 hr (IV/IM); 4-6 hr (PO)
Peak serum time: 15 min (IM); 2-3 hr (PO)
Distribution
Protein bound: 10-19%
Vd: 1.4 L/kg (normal renal function)
Metabolism
Metabolized in liver
Metabolites: Ranitidine N-oxide, desmethylranitidine, ranitidine S-oxide (inactive)
Enzymes inhibited: Unlike cimetidine, ranitidine does not inhibit microsomal enzymes
Elimination
Half-life: 2.5-3 hr (PO; increases to 4.8 hr with CrCl 25-35 mL/min); 2-2.5 hr (IV)
Dialyzable: Yes (HD, PD)
Renal clearance: 25 L/hr
Total body clearance: 1.29-1.44 L/hr/kg
Excretion: Urine (30% PO; 70% IV)
Administration
IV Compatibilities
Solution: Compatible with most common solvents
Additive (partial list): Ampicillin(?), ciprofloxacin, dexamethasone, dobutamine, dopamine, epinephrine, erythromycin, floxacillin, fluconazole with ondansetron, furosemide, gentamicin, heparin, lidocaine, midazolam, norepinephrine (incompatible at 2 g), penicillin G potassium/sodium, potassium chloride, protamine sulfate, sodium nitroprusside, vancomycin
Syringe (partial list): Atropine, dexamethasone, dimenhydrinate, diphenhydramine, dobutamine, dopamine, fentanyl, glycopyrrolate, heparin, hydromorphone, metoclopramide, morphine hydrochloride/sulfate, prochlorperazine, promethazine
Y-site (partial list): Acyclovir, allopurinol, ceftazidime, ciprofloxacin, diltiazem, dobutamine, dopamine, epinephrine, esmolol, fentanyl, furosemide, heparin, linezolid, lorazepam, midazolam, morphine sulfate, nitroglycerin, norepinephrine, ondansetron, propofol, vecuronium, warfarin, zidovudine
IV Incompatibilities
Solution: D5W in LR(?)
Additive: Amphotericin B, atracurium, cefamandole, cefazolin, cefoxitin, ceftazidime, cefuroxime, clindamycin(?), ethacrynate, insulin(?), phytonadione
Syringe: Chlorpromazine(?), diazepam(?), hydroxyzine, lorazepam(?), methotrimeprazine, midazolam, papaveretum, pentobarbital, phenobarbitaL
Y-site: Amphotericin B cholesteryl sulfate, hetastarch, insulin
IV Administration
Direct injection: 50 mg diluted to ≥20 mL with compatible IV infusion fluid and given over ≥5 minutes (4 mL/min)
Intermittent infusion: 50 mg added to ≥100 mL of compatible IV solution and infused over 15-20 minutes
Continuous infusion: 150 mg diluted in 250 mL of IV fluid and infused at 6.25 mg/hr for 24 hours
IM Administration
Administer undiluted
Storage
Store at 4-30°C (39-86°F)
Protect from light and excessive heat
