High-output heart failure
High-output heart failure happens when the amount of blood pumped out is more than typical and the heart is unable to keep up. This can occur in overload situations such as blood or serum infusions, kidney diseases, chronic severe anemia, beriberi (vitamin B1/thiamine deficiency), hyperthyroidism, cirrhosis, Pagets disease, multiple myeloma, arteriovenous fistulae, or arteriovenous malformations. Acute decompensation
Chronic stable heart failure may easily decompensate. This most commonly results from a concurrent illness (such as myocardial infarction (a heart attack) or pneumonia), abnormal heart rhythms, uncontrolled hypertension, or a persons failure to maintain a fluid restriction, diet, or medication.Other factors that may worsen CHF include: anemia, hyperthyroidism, excessive fluid or salt intake, and medication such as NSAIDs and thiazolidinediones. NSAIDs increase the risk twofold. Medications
A number of medications may cause or worsen the disease. This includes NSAIDs, COX-2 inhibitors, a number of anesthetic agents such as ketamine, thiazolidinediones, some cancer medications, several antiarrhythmic medications, pregabalin, alpha-2 adrenergic receptor agonists, minoxidil, itraconazole, cilostazol, anagrelide, stimulants (e.g., methylphenidate), tricyclic antidepressants, lithium, antipsychotics, dopamine agonists, TNF inhibitors, calcium channel blockers (especially verapamil and diltiazem), salbutamol, and tamsulosin.By inhibiting the formation of prostaglandins, NSAIDs may exacerbate heart failure through several mechanisms, including promotion of fluid retention, increasing blood pressure, and decreasing a persons response to diuretic medications. Similarly, the ACC/AHA recommends against the use of COX-2 inhibitor medications in people with heart failure.
Based on data from the manufacturer, it is expected that 0.6% of the maternal weight-adjusted dose would reach a breastfed infant, though the effects in the infant are unknown. Renal impairment
Renal impairment does not appear to affect the pharmacokinetic profile of zafirlukast. Hepatic impairment
The hepatic clearance of zafirlukast is impaired by significant hepatic impairment. Cirrhosis of the liver can result in an increase in the maximum plasma concentration and the total area under the curve (a measure of drug exposure) by 50–60%. Contraindications
Zafirlukast is contraindicated in people that are hypersensitive or allergic to it. Adverse effects
Zafirlukast is generally well tolerated, though headache and gastrointestinal (GI) upset can occur. The incidence of headache is between 12 and 20%, which is similar to the incidence of headache found in patients taking placebos in the studies that lead to zafirlukasts approval. GI upset may include nausea, stomach discomfort/pain, and diarrhea. GI complaints can be lessened by taking zafirlukast with food, though this can dramatically impair the amount of drug that gets absorbed into the body (see the section on drug-food interactions below).Other common side effects include flu-like symptoms, sleep disturbances (abnormal dreams, insomnia), hallucinations, and daytime drowsiness. Neuropsychiatric effects
Neuropsychiatric side effects have been reported with the use of zafirlukast and other LTRAs. While some side effects are less severe (e.g. abnormal dreams), others are more serious (e.g. hallucinations, tremor, suicidality). These effects were discovered through post-marketing reports, as the initial trials were not designed to monitor for neuropsychiatric side effects.