What is the equivalent dosage when converting from oral Clonidine (antihypertensive medication) 0.1 milligrams to a transdermal patch?

From the Guidelines

When transitioning from oral clonidine 0.1 mg to a clonidine patch, apply a Catapres-TTS-1 patch (releasing 0.1 mg of clonidine per day) while continuing the oral medication for 2-3 days, then discontinue the oral form. This approach is based on the guideline evidence from 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.

Key Considerations

• The patch should be applied to a hairless, clean, dry area of the upper arm or torso, and replaced every 7 days at a different site to prevent skin irritation.
• The patch provides more consistent blood levels than oral dosing, which helps reduce blood pressure fluctuations and side effects like drowsiness.
• When discontinuing patch therapy, taper gradually to avoid rebound hypertension by using a lower strength patch or increasing the time between applications.

Monitoring and Adjustments

• Monitor blood pressure during the transition period, as some patients may require dosage adjustments.
• The patch formulation improves adherence due to weekly rather than daily dosing, but may cause skin reactions in some patients.
• If skin irritation occurs, rotating application sites and ensuring the area is completely dry before application can help minimize this side effect.

Rationale

The clonidine patch is generally reserved as a last-line treatment due to significant CNS adverse effects, especially in older adults, but it offers a convenient weekly dosing regimen that can enhance patient compliance 1. By following the recommended transition protocol and monitoring for potential side effects, healthcare providers can effectively manage patients switching from oral clonidine to the patch formulation.

From the FDA Drug Label

To initiate therapy, Clonidine Transdermal System dosage should be titrated according to individual therapeutic requirements, starting with Clonidine Transdermal System 0. 1 mg. If after one or two weeks the desired reduction in blood pressure is not achieved, increase the dosage by adding another Clonidine Transdermal System 0.1 mg or changing to a larger system. When substituting Clonidine Transdermal System for oral clonidine or for other antihypertensive drugs, physicians should be aware that the antihypertensive effect of Clonidine Transdermal System may not commence until 2-3 days after initial application. Therefore, gradual reduction of prior drug dosage is advised

The patient can be switched from oral Clonidine 0.1 mg to a Clonidine Transdermal System 0.1 mg/day patch.

• The patch should be applied once every 7 days to a hairless area of intact skin on the upper outer arm or chest.
• Gradual reduction of the prior oral Clonidine dosage is advised when substituting with the transdermal system, as the antihypertensive effect of the patch may not commence until 2-3 days after initial application 2.

From the Research

Changing from Oral Clonidine to Patch

• The decision to change from oral Clonidine 0.1 mg to a patch should be based on the patient's individual needs and medical history 3, 4.
• Transdermal Clonidine has been shown to be effective in reducing blood pressure in patients with mild to moderate hypertension, with a more stable blood pressure control compared to oral Clonidine 3, 4, 5.
• The transdermal patch provides a constant rate of Clonidine delivery over 7 days, which can improve compliance and reduce side effects such as dry mouth and drowsiness 3, 4, 5.
• However, some patients may experience adverse skin reactions to the transdermal patch, and the incidence of side effects may vary between individuals 3, 4, 5.

Dosage and Administration

• The dosage of transdermal Clonidine should be titrated up from the smallest system (3.5 cm2) until the desired pharmacological effect is obtained 3.
• The rate of Clonidine release from the transdermal patch is controlled by the microporous membrane, and the daily dose is regulated by the area of skin covered 3.
• Steady-state plasma concentrations of Clonidine are typically reached on the fourth day after initial transdermal system application 3.

Safety and Efficacy

• Transdermal Clonidine has been shown to be safe and effective in reducing blood pressure in patients with mild to moderate hypertension 3, 4, 5.
• However, there is limited data on the use of Clonidine in hospitalized patients with asymptomatic severe hypertension, and the response to Clonidine can be unpredictable 6.
• Clonidine can cause adverse reactions, including acute kidney injury, and should be used with caution in older patients and those with preexisting vascular disease 6, 7.