Zafirlukast
Mechanism :
It is a leukotriene antagonist. Zafirlukast selectively antagonises the leukotriene D4 receptor. It inhibits bronchoconstriction caused by various inhaled antigens or irritants. It is not used in acute asthma attacks.
Indication :
Contraindications :
Hypersensitivity, Hepatic impairment, Cirrhosis, Acute asthmatic attacks.
Dosing :
Oral dose. Taken 1 hour before or 2 hours after meals.
<5 years of age: Safety and efficacy has not been established.
5-11 years: 10 mg bid.
>12 years: 20 mg bid.
Adverse Effect :
GI disturbances, headache, myalgia, generalised pain, fever, dizziness, raised LFT, respiratory tract infections, hypersensitivity reactions, Churg-Strauss syndrome, severe hepatotoxicity.
Interaction :
Aspirin: High dose aspirin increases plasma concentration of zafirlukast.
Theophylline, Terfenadine and Erythromycin: Zafirlukast plasma concentration is reduced. Warfarin: It enhances warfarin anticoagulant activity.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-50 | Dose as in normal renal function |
| 10-20 | Dose as in normal renal function, but use with care |
| <10 | Dose as in normal renal function, but use with care |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Unlikely to be dialysed. Dose as in normal renal function, but use with care |
| HD | Unlikely dialysability. Dose as in normal renal function, but use with care |
| HDF/High flux | Unknown dialysability. Dose as in normal renal function, but use with care |
| CAV/VVHD | Unknown dialysability. Dose as in normal renal function, but use with care |
Hepatic Dose :
In hepatic impairment, use of this drug is contraindicated due to reduced clearance and increased exposure.