Trade Name(s)

  • Karbinal ER
  • Ryvent

Ther. Class.

allergy, cold and cough remedies

Pharm. Class.



  • Seasonal and perennial allergic rhinitis.
  • Vasomotor rhinitis.
  • Allergic conjunctivitis due to inhalant allergens and foods.
  • Mild, uncomplicated allergic skin manifestations of urticaria and angioedema.
  • Dermatographism.
  • Anaphylaxis (as adjunct to epinephrine after acute manifestations controlled).
  • Allergic reactions to blood or plasma.


Antagonizes the effects of histamine at H1 –receptor sites; does not bind to or inactivate histamine. Significant CNS depressant and anticholinergic properties.

Therapeutic Effect(s):

Decreased symptoms of histamine excess (sneezing, rhinorrhea, nasal/ocular pruritus, ocular tearing/redness and skin itching/urticaria).


Absorption: Well absorbed following oral administration

Distribution: Unknown

Metabolism and Excretion: Extensively metabolized by the liver, inactive metabolites excreted in urine. Negligible renal elimination of unchanged drug.

Half-life: 17 hr

TIME/ACTION PROFILE (plasma concentrations)

PO-IRunknownunknown4 hr
PO-ERunknown6.7 hr12 hr


Contraindicated in:

  • Hypersensitivity, including sulfite allergy
  • Lactation: Lactation;
  • Concurrent use of MAO inhibitors
  • Pedi:   Children <2 yr (↑ risk of death).

Use Cautiously in:

  • Increased intraocular pressure or narrow angle glaucoma
  • Hyperthyroidism
  • Cardiovascular disease including hypertension
  • Stenosing peptic ulcer or pyloroduodenal obstruction
  • Symptomatic prostatic hypertrophy or bladder neck obstruction
  • OB:  Safety not established in pregnancy;
  • Pedi:  Younger children may be more sensitive to sedation or excitation
  • Geri:  Older adults may be more susceptible to adverse reactions.

Adverse Reactions/Side Effects

GI: epigastric distress

Neuro: disturbed coordination, dizziness, drowsiness, sedation

Resp: thickened bronchial secretions

* CAPITALS indicate life-threatening.
Underline indicate most frequent.



  • Concurrent use with  MAO inhibitors  may ↑ anticholinergic effects.
  • ↑ risk of CNS depression with other  CNS depressants  including  alcohol, other  antihistamines ,  opioid analgesics  and  sedative/hypnotics.


PO (Adults and Children ≥ 12 yr): Immediate-release tablets or solution: 4–8 mg 3–4 times daily;  Extended-release suspension: 6–16 mg every 12 hr.

PO (Children 6–11 yr): Immediate-release tablets or solution: 2–4 mg 3–4 times daily;  Extended-release suspension: 6–12 mg every 12 hr.

PO (Children 4–5 yr): Immediate-release solution: 1–2 mg 3–4 times daily;  Extended-release suspension: 3–8 mg every 12 hr.

PO (Children 2–3 yr): Immediate-release solution: 1–2 mg 3–4 times daily;  Extended-release suspension: 3–4 mg every 12 hr.

Availability (generic available)

Immediate-release tablets: 4 mg, 6 mg

Immediate-release oral solution (banana bubble gum flavor): 4 mg/5 mL

Extended-release oral suspension (contains metabisulfite) (strawberry banana flavor): 4 mg/5 mL


  • Assess allergy symptoms (rhinitis, conjunctivitis, hives) before and periodically during therapy
  • Assess lung sounds and character of bronchial secretions. Maintain fluid intake of 1500–2000 mL/day to decrease viscosity of secretions

Lab Test Considerations:

May case ↑ uric acid levels.


  • Begin with lowest dose and increase as needed and tolerated. Dose is based on condition severity and patient response.
  • PO Administer twice daily.
    • Use a calibrated measuring device for accurate dose; household tablespoon is not accurate and could lead to overdose. May be fatal if administered to children under 2 yr.Shake well before using.

Patient/Family Teaching

  • Instruct patient to take medication as directed
  • May cause dizziness and drowsiness. Caution patient to avoid driving or other activities requiring alertness until response to medication is known
  • Advise patient to avoid taking alcohol or other CNS depressants concurrently with this drug, may cause overdose.
  • Advise patient that good oral hygiene, frequent rinsing of mouth with water, and sugarless gum or candy may minimize dry mouth. Patient should notify dentist if dry mouth persists >2 wk
  • Rep:  Instruct females of reproductive potential to notify health care professional if pregnancy is planned or suspected and avoid breastfeeding during therapy.

Evaluation/Desired Outcomes

Decrease in allergic symptoms