Drug information of Clemastine

Mechanism of effect

Histamine H1 antagonist in the gastrointestinal tract, blood vessels, and respiratory tract; anticholinergic and sedative effects are also seen.

Pharmacodynamic

Competes with histamine for H1-receptor sites on effector cells in the gastrointestinal tract, blood vessels, and respiratory tract.

Pharmacokinetics

• Time to peak: 2 to 4 hours
• Metabolism: Hepatic
• Half-life elimination: ~21 hours
• Excretion: Urine
• Small amounts of clemastine may be excreted in breast milk

Drug indications

Urticaria , Allergic Rhinitis

Dosage

Adults:
• Allergic rhinitis
- Oral: Clemastine fumarate 1.34 mg (1 mg base) twice daily; daily or a single 2.68 mg dose, repeat as needed up to a maximum of 2.68 mg 3 times a day. Maximum daily dose: Clemastine fumarate 8.04 mg/day (6 mg/day base)
- Common cold/hay fever/upper respiratory allergies (OTC labeling): Oral: Clemastine fumarate 1.34 mg (1 mg base) twice daily. Maximum daily dose: Clemastine fumarate 2.68 mg/day (2 mg/day base)
- Urticaria/angioedema: Oral: Clemastine fumarate 2.68 mg (2 mg base) twice daily or a single 2.68 mg dose, repeat as needed up to a maximum of 2.68 mg 3 times a day. Maximum daily dose: Clemastine fumarate 8.04 mg/day (6 mg/day base)
Pediatric
• Allergic rhinitis
- <6 years: Oral: Clemastine fumarate 0.335-0.67mg/day ( 0.25-0.5 mg base/day) divided q8-12hr; not to exceed 1.34 mg (1mg base)
- 6 to <12 years: Oral: Clemastine 0.67-1.34 mg (0.5-1 mg base) q12hr;not to exceed 4.02mg/day (3mg/day base)
- >12 years : Referred to adult dose
- Urticaria/angioedema
- <6 years: Referred to allergic rhinitis
- 6 to <12 years: Oral: Clemastine 0.67-1.34 mg (0.5-1 mg base) q12hr;not to exceed 4.02mg/day (3mg/day base)
- >12 years: Referred to adult dose

Drug contraindications

hypersensitivity to this drug

Side effects

nausea , dry mouth , constipation , abdominal pain , dizziness , vomiting , Blurred vision , vertigo , Diarrhea , hypotension , palpitations , anorexia , urinary retention , Tinnitus , Urinary frequency , difficulty urinating , skin rush

Interactions

Acetylcholine , Alprazolam , Amitriptyline , Tranylcypromine , Salmeterol , Phenobarbital , Clozapine , isocarboxazid , کافئین , potassium citrate , Sodium Oxybate , glycopyrrolate topical , lasmiditan

Alerts

Use clemastin with caution in patients with angle-closure (narrow angle) glaucoma, prostatic hypertrophy, thyroid dysfunction, gastrointestinal and genitourinary obstruction, cardiovascular disease, asthma

Points of recommendation

May cause CNS depression, which may impair physical or mental abilities; patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving

Pregnancy level

B

Related drugs

Loratadin , Hydroxyzine , Chlorpheniramine , Cetirizine , Bepotastine , Azatadine , Carbinoxamine , pyrilamine (Mepyramine) , Phenindamine , Triprolidine , Tripelennamine , Trimeprazine , Terfenadine