Terfenadine Pharmacology

Terfenadine

About Terfenadine
Second generation histamine H1 antagonist, Benzhydryl derivative, Antihistamine.
Mechanism of Action of Terfenadine
Terfenadine competitively bind to the histamine H1-receptors on the GI tract, uterus, large blood vessels, and bronchial muscle. This reversible binding of terfenadine suppresses the formation of edema, flare, and pruritis resulting from histaminic activity. In large dose it also inhibits cardiac potassium channels.
Pharmacokinets of Terfenadine
Absorption- Moderately absorbed after oral administration.
Distribution- Widely distributed in the body. 70% bound to the plasma Proteins.
Metabolism- Metabolized in the liver to its metabolites. Fexofenadine is its active metabolite.
Excretion- Excreted via urine and feces.
Onset of Action for Terfenadine
1 - 2 hr
Duration of Action for Terfenadine
>12 hr
Half Life of Terfenadine
3.5 hrs
Side Effects of Terfenadine
1. Difficulty breathing
2. Closing of throat
3. Swelling of lips, tongue, or face
4. Hives
5. Irregular heartbeat
6. Seizures
7. Drowsiness
8. Dizziness
9. Headache
10. Nervousness
11. Nausea
12. Diarrhea
13. Abdominal discomfort
14. Dry mouth
15. Dry skin
16. Itchiness
Contra-indications of Terfenadine
1. Hypersensitivity to the drug
2. Severe hepatic dysfunction

Special Precautions while taking Terfenadine
1. Liver disease
2. Asthma or other lung disease
3. Glaucoma
4. Enlarged prostate gland
5. Heart disease
6. High blood pressure
7. Overactive thyroid gland
8. Stomach ulcers
9. Urinary tract blockage
10. Kidney disease
11. Drug allergies
12. Any work which require mental alertness like driving and machine operations

Pregnancy Related Information
Use with caution
Old Age Related Information
Use with caution
Breast Feeding Related Information
Use with caution
Children Related Information
Use with caution
Indications for Terfenadine
1. Rash
2. Hives
3. Watery eyes
4. Runny nose
5. Itching eyes
6. Sneezing.
7. Atopic dermatitis
8. Dermo-graphism
9. Common cold
10. Asthma (induced by atophy or exercise)
Interactions for Terfenadine
Itraconazole and other Azole - type antifungal agents (including Fluconazole, Metronidazole, Miconazole and Ketoconazole): QT interval prolongation and rare serious cardiac events like death, cardiac arrest and ventricular arrhythmias may occur because ketoconazole markedly inhibits metabolism of terfenadine. Hence concomitant administration of ketoconazole and terfenadine is contraindicated.
Macrolides (e.g. Erythomycin, Clarithromycin): Coadministration with terfenadine is contraindicated.
Alcohol, CNS depressants: Additive CNS depressant effects may occur.
Food: Reduces absorption.
Typical Dosage for Terfenadine
Oral- General Dose.
Adult-
60mg twice daily OR 120mg once daily.
Children-
For 3-5 yrs-15mg twice daily.
For 6-12 yrs- 30-60 mg twice daily.

Schedule of Terfenadine
H
Storage Requirements for Terfenadine
Store at room temperature away from moisture and heat.
Effects of Missed Dosage of Terfenadine
Take the missed dose as soon as noticed and if it is the time for next dose then skip the missed dose. Continue the regular schedule. Do not double the dose.
Effects of Overdose of Terfenadine
Give symptomatic and supportive treatment.

Home Delivery for Terfenadine in Your City

Medicine India is just a publishing medium for medicine related information and does not provide services or sales of medicines including terfenadine.

However, we do publish a comprehensive directory of Pharmacies, Chemists and Druggists in cities all over India. You can use this directory to find the medicine stores in your city (or area) that provide home delivery services for terfenadine and other medicines and health products. Home delivery services for terfenadine may be free or they may cost you depending on the pharmacy and the minimum order requirements. It would be best to get this clarified while placing the order.

Please be aware that you should take terfenadine only if a doctor has recommended or prescribed it. Some or all pharmacies who provide a home delivery service for medicines might insist on a prescription for terfenadine before they complete the sale. You can get this information while placing the order for terfenadine with the pharmacy.

Terfenadine is a generic medicine name and there are several brands available for it. Some of the brands for terfenadine might be better known than terfenadine itself. If the pharmacy that's willing to deliver medicines to your home doesn't have terfenadine in stock, you can ask for one of the branded alternatives for terfenadine.