Formistin - General Information
A potent second-generation histamine H1 antagonist that is effective in the treatment of allergic rhinitis, chronic urticaria, and pollen-induced asthma. Unlike many traditional antihistamines, it does not cause drowsiness or anticholinergic side effects. [PubChem]
Pharmacology of Formistin
Formistin, the active metabolite of the piperazine H1-receptor antagonist hydroxyzine, is used to treat chronic idiopathic urticaria, perennial allergic rhinitis, seasonal allergic rhinitis, allergic asthma, physical urticaria, and atopic dermatitis.
Formistin for patients
What is cetirizine?
- Cetirizine is an antihistamine. Cetirizine blocks the actions of the naturally occurring chemical histamine in the body. Cetirizine is less likely than some other antihistamines to cause side effects such as drowsiness and dizziness.
- Cetirizine is used to treat the symptoms of allergies such as sneezing; runny nose; itching, tearing, and redness of the eyes; and hives.
- Cetirizine may also be used for purposes other than those listed in this medication guide.
What should I discuss with my healthcare provider before taking cetirizine?
- Do not take cetirizine without first talking to your doctor if you have had an allergic reaction to it or to the medication hydroxyzine (Atarax, Vistaril).
- Before taking cetirizine, tell your doctor if you have kidney or liver disease. You may need a dosage adjustment or special monitoring during treatment.
- Cetirizine is in the FDA pregnancy category B. This means that it is not expected to be harmful to an unborn baby. Do not take cetirizine without first talking to your doctor if you are pregnant or could become pregnant during treatment.
- Cetirizine passes into breast milk and may affect a nursing baby. Do not take cetirizine without first talking to your doctor if you are breast-feeding a baby.
- If you are over 65 years of age, you may be more likely to experience side effects from cetirizine. Your doctor may prescribe a lower dose of this medication.
How should I take cetirizine?
- Take cetirizine exactly as directed by your doctor. If you do not understand these directions, ask your pharmacist, nurse, or doctor to explain them to you.
- Take the tablets with a full glass of water.
- Chew the chewable tablets thoroughly before swallowing.
- To ensure you get the correct dose, measure the liquid form of cetirizine with a dose-measuring spoon, cup, or dropper, not with a regular table spoon. If you do not have a dose-measuring device, ask your pharmacist where you can get one.
- Cetirizine can be taken with or without food.
- Store cetirizine at room temperature away from moisture and heat.
Pharmacokinetic interaction studies with cetirizine in adults were conducted with pseudoephedrine, antipyrine, ketoconazole, erythromycin and azithromycin. No interactions were observed. In a multiple dose study of theophylline (400 mg once daily for 3 days) and cetirizine (20 mg once daily for 3 days), a 16% decrease in the clearance of cetirizine was observed. The disposition of theophylline was not altered by concomitant cetirizine administration.
Drug-Drug Interactions: No clinically significant drug interactions have been found with theophylline at a low dose, azithromycin, pseudoephedrine, ketoconazole, or erythromycin. There was a small decrease in the clearance of cetirizine caused by a 400-mg dose of theophylline; it is possible that larger theophylline doses could have a greater effect.
Cetirizine is contraindicated in those patients with a known hypersensitivity to it or any of its ingredients or hydroxyzine.
Additional information about Formistin
Formistin Indication: For the relief of symptoms associated with seasonal allergic rhinitis, perennial allergic rhinitis and the treatment of the uncomplicated skin manifestations of chronic idiopathic urticaria
Mechanism Of Action: Formistin competes with histamine for binding at H1-receptor sites on the effector cell surface, resulting in suppression of histaminic edema, flare, and pruritus. The low incidence of sedation can be attributed to reduced penetration of cetirizine into the CNS as a result of the less lipophilic carboxyl group on the ethylamine side chain.
Drug Interactions: Not Available
Food Interactions: Avoid alcohol.
Take without regard to meals.
Generic Name: Cetirizine
Synonyms: Cetirizina [Spanish]; Cetirizinum [Latin]; Cetrizine Hcl
Drug Category: Anti-Allergic Agents; Antihistamines
Drug Type: Small Molecule; Approved
Absorption: mean peak plasma concentration (Cmax) of 114 ng/mL at a time (Tmax) of 2.2 hours postdose was observed for cetirizine
Toxicity (Overdose): Somnolence (sleepiness or unusual drowsiness), restlessness, irritability
Protein Binding: Very high (93%) plasma protein binding
Biotransformation: Not Available
Half Life: 8.3 hours
Dosage Forms of Formistin: Tablet Oral
Chemical IUPAC Name: 2-[2-[4-[(4-chlorophenyl)-phenylmethyl]piperazin-1-yl]ethoxy]acetic acid
Chemical Formula: C21H25ClN2O3
Cetirizine on Wikipedia: https://en.wikipedia.org/wiki/Cetirizine
Organisms Affected: Humans and other mammals