DOSAGE AND ADMINISTRATION
Congestive Heart Failure Post-Myocardial Infarction
Treatment should be initiated at 25 mg once daily and titrated to the recommended dose of 50 mg once daily, preferably within 4 weeks as tolerated by the patient. INSPRA may be administered with or without food.
Once treatment with INSPRA has begun, adjust the dose based on the serum potassium level as shown in Table 1.
Table 1. Dose Adjustment in Congestive Heart Failure Post-MI Serum Potassium
(mEq/L) | Action | Dose Adjustment |
| < 5.0 | Increase | 25 mg every other day to 25 mg once daily
25 mg once daily to 50 mg once daily |
| 5.0—5.4 | Maintain | No adjustment |
| 5.5—5.9 | Decrease | 50 mg once daily to 25 mg once daily
25 mg once daily to 25 mg every other day
25 mg every other day to withhold |
| ≥ 6.0 | Withhold | Restart at 25 mg every other day when potassium levels fall to <5.5 mEq/L |
Hypertension
The recommended starting dose of INSPRA is 50 mg administered once daily. The full therapeutic effect of INSPRA is apparent within 4 weeks. For patients with an inadequate blood pressure response to 50 mg once daily the dosage of INSPRA should be increased to 50 mg twice daily. Higher dosages of INSPRA are not recommended because they have no greater effect on blood pressure than 100 mg and are associated with an increased risk of hyperkalemia. [See CLINICAL STUDIES.]
Recommended Monitoring
Serum potassium should be measured before initiating INSPRA therapy, within the first week, and at one month after the start of treatment or dose adjustment. Serum potassium should be assessed periodically thereafter. Patient characteristics and serum potassium levels may indicate that additional monitoring is appropriate. [See WARNINGS AND PRECAUTIONS, ADVERSE REACTIONS.] In the EPHESUS study [See CLINICAL STUDIES], the majority of hyperkalemia was observed within the first three months after randomization.
In all patients taking INSPRA who start taking a moderate CYP3A4 inhibitor, check serum potassium and serum creatinine in 3—7 days.
Dose Modifications for Specific Populations
For hypertensive patients receiving moderate CYP3A4 inhibitors (e.g., erythromycin, saquinavir, verapamil, and fluconazole), the starting dose of INSPRA should be reduced to 25 mg once daily. [See DRUG INTERACTIONS.]
No adjustment of the starting dose is recommended for the elderly or for patients with mild-to-moderate hepatic impairment. [See CLINICAL PHARMACOLOGY.]
DOSAGE FORMS AND STRENGTHS
- 25 mg tablets: yellow diamond biconvex film-coated tablets debossed with Pfizer on one side and NSR over 25 on the other
- 50 mg tablets: yellow diamond biconvex film-coated tablets debossed with Pfizer on one side and NSR over 50 on the other
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