Table 3. Drugs that do not interfere with calculating the aldosterone:renin ratio5.

	Starting dose	Maximum dose
Sustained-release verapamil*	180 mg daily	240 mg daily
Moxonidine	200 micrograms once at night	200 micrograms twice daily after two weeks
Prazosin	0.5 mg twice daily	5 mg three times a day
Hydralazine hydrochloride	12.5 mg twice daily	50 mg three times a day

* Administration of verapamil as two divided doses may provide better coverage over 24 hours, if necessary. Doses higher than 240 mg daily may be used, but are often limited by adverse effects, therefore addition of a second drug is advised before increasing the verapamil dose.