From the Guidelines
Clonidine should not be used as a PRN medication due to potential risks and inconsistent blood pressure control, but if used, a typical dose would be 0.1 mg taken orally as needed, not to exceed 0.4 mg in 24 hours, under close medical supervision and for specific indications, such as acute hypertensive episodes or opioid withdrawal symptoms, as stated in the 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults 1. When using clonidine, patients should be instructed to:
- Monitor blood pressure before and after taking the medication
- Avoid sudden discontinuation, which can cause rebound hypertension
- Be aware of potential side effects like drowsiness and dry mouth The reason for caution with PRN use is that clonidine has a relatively short half-life and works by reducing sympathetic nervous system activity, as noted in the guideline 1. Inconsistent use can lead to fluctuations in blood pressure and potentially dangerous rebound effects. Regular, scheduled dosing provides more stable blood pressure control and reduces risks associated with sudden changes in medication levels. Key considerations for clonidine use include:
- Significant CNS adverse effects, especially in older adults, as mentioned in the guideline 1
- Risk of rebound hypertension with abrupt discontinuation, as stated in the guideline 1
- Need for close medical supervision and monitoring of blood pressure and potential side effects, as recommended in the guideline 1
From the FDA Drug Label
Clonidine hydrochloride tablets, USP are indicated in the treatment of hypertension. Clonidine hydrochloride tablets, USP may be employed alone or concomitantly with other antihypertensive agents. The indication for Clonidine is for the treatment of hypertension. There is no mention of "as needed" in the provided drug label, so the specific indication for "as needed" use cannot be determined. 2
From the Research
Indications for Clonidine
- Hypertensive emergencies and urgencies: Clonidine can be used to control severe elevations of blood pressure in hypertensive crisis 3, 4, 5.
- Severe hypertension: Oral clonidine rapid titration can be effectively and safely used for treating severe hypertension even in an ambulatory setting 4.
- Migraine prophylaxis: Clonidine in low dosages (75 to 150 mug daily) is useful in preventing migraine headaches in about 30%-50% of patients 6.
- Hot flashes secondary to leuprolide or goserelin: Clonidine can be used to treat hot flashes in men receiving either leuprolide or goserelin for prostate cancer 7.
Dosage and Administration
- Hypertensive emergencies and urgencies: An initial oral dose of 0.1 to 0.2 mg of clonidine hydrochloride followed by hourly doses of 0.05 or 0.1 mg until goal blood pressure is attained 3.
- Severe hypertension: 0.2 mg as the initial dose followed by 0.2 or 0.1 mg at one hour and then 0.1 mg/hour, for a total dose of 0.8 mg 4.
- Migraine prophylaxis: 75 to 150 mug daily 6.
- Hot flashes secondary to leuprolide or goserelin: 0.1-0.2 mg/d, with dosages increased in increments of 0.1-0.3 mg/d every two to four weeks if symptoms persist or until adverse effects develop 7.