Clonidine

CLONIDINE- clonidine patch, extended release
Dr. Reddy’s Labratories Inc.

chemical-structurecross-sectionFigure-1Figure-2-LFigure-2-RFigure-3Figure-4Figure-5Figure-6Principle Display Panel 0.2mgprinciple display panel 0.1mgprinciple display panel 0.3mg

Programmed delivery in vivo of 0.1, 0.2, or 0.3 mg clonidine USP per day, for one week.

Rx only

DESCRIPTION

Clonidine transdermal system USP provides continuous systemic delivery of clonidine USP for 7 days at an approximately constant rate. Clonidine USP is a centrally acting alpha-agonist hypotensive agent. It is an imidazoline derivative with the chemical name 2, 6-dichloro-N-2-imidazolidinylidenebenzenamine and has the following chemical structure:

chemical-structure
(click image for full-size original)
C9 H9 Cl2 N3 M.W. 230.10

System Structure and Components

Clonidine transdermal system USP is a multi-layered film, 0.2 mm thick, containing clonidine USP as the active agent. The system areas are 4.33 cm2 (clonidine USP 0.1 mg per day), 8.67 cm2 (clonidine USP 0.2 mg per day) and 13 cm2 (clonidine USP 0.3 mg per day) and the amount of drug released is directly proportional to the area (see Release Rate Concept). The composition per unit area is the same for all three doses. The inactive ingredients are: aluminum, colloidal silicon dioxide, ethylene vinyl acetate copolymer, light mineral oil, microporous polypropylene membrane, pigmented polyethylene polyester film, polyisobutylene and silicon coated polyester film.

Proceeding from the visible surface towards the surface attached to the skin, there are four consecutive layers: 1) a backing layer of polyester film; 2) a drug reservoir; 3) a microporous polypropylene membrane that controls the rate of delivery of clonidine USP from the system to the skin surface; 4) an adhesive formulation. Prior to use, a protective slit release liner of silicone coated polyester film that covers the adhesive layer is removed.

Cross Section of the System:

cross-section
(click image for full-size original)

Release Rate Concept

Clonidine transdermal system USP is programmed to release clonidine USP at an approximately constant rate for 7 days. The energy for drug release is derived from the concentration gradient existing between a saturated solution of drug in the system and the much lower concentration prevailing in the skin. Clonidine USP flows in the direction of the lower concentration at a constant rate, limited by the rate-controlling membrane, so long as a saturated solution is maintained in the drug reservoir.

Following system application to intact skin, clonidine USP in the adhesive layer saturates the skin site below the system. Clonidine USP from the drug reservoir then begins to flow through the rate-controlling membrane and the adhesive layer of the system into the systemic circulation via the capillaries beneath the skin. Therapeutic plasma clonidine USP levels are achieved 2 to 3 days after initial application of clonidine transdermal system USP.

The 4.33, 8.67 and 13 cm2 systems deliver 0.1, 0.2, and 0.3 mg of clonidine USP per day, respectively. To ensure constant release of drug for 7 days, the total drug content of the system is higher than the total amount of drug delivered. Application of a new system to a fresh skin site at weekly intervals continuously maintains therapeutic plasma concentrations of clonidine USP. If the clonidine transdermal system USP is removed and not replaced with a new system, therapeutic plasma clonidine USP levels will persist for about 8 hours and then decline slowly over several days. Over this time period, blood pressure returns gradually to pretreatment levels.

CLINICAL PHARMACOLOGY

Clonidine stimulates alpha-adrenoreceptors in the brain stem. This action results in reduced sympathetic outflow from the central nervous system and in decreases in peripheral resistance, renal vascular resistance, heart rate, and blood pressure. Renal blood flow and glomerular filtration rate remain essentially unchanged. Normal postural reflexes are intact; therefore, orthostatic symptoms are mild and infrequent.

Acute studies with clonidine hydrochloride in humans have demonstrated a moderate reduction (15% to 20%) of cardiac output in the supine position with no change in the peripheral resistance; at a 45° tilt there is a smaller reduction in cardiac output and a decrease of peripheral resistance.

During long-term therapy, cardiac output tends to return to control values, while peripheral resistance remains decreased. Slowing of the pulse rate has been observed in most patients given clonidine, but the drug does not alter normal hemodynamic responses to exercise.

Tolerance to the antihypertensive effect may develop in some patients, necessitating a reevaluation of therapy.

Other studies in patients have provided evidence of a reduction in plasma renin activity and in the excretion of aldosterone and catecholamines. The exact relationship of these pharmacologic actions to the antihypertensive effect of clonidine has not been fully elucidated.

Clonidine acutely stimulates the release of growth hormone in children as well as adults but does not produce a chronic elevation of growth hormone with long-term use.

Pharmacokinetics

Clonidine transdermal system delivers clonidine at an approximately constant rate for 7 days. The absolute bioavailability of clonidine from the clonidine transdermal system dosage form is approximately 60%. Steady-state clonidine plasma levels are obtained within 3 days after transdermal application to the upper outer arm and increase linearly with increasing size of the transdermal patch. Mean steady-state plasma concentrations with the 4.33 cm2 , 8.67 cm2 and 13 cm2 systems are approximately 0.4 ng/mL, 0.8 ng/mL, and 1.1 ng/mL, respectively. Similar clonidine steady-state concentrations are reached after application to the chest. Steady-state clonidine plasma levels remain constant after removal of one system and application of a new system of the same size.

Following intravenous administration, clonidine displays biphasic disposition with a distribution half-life of about 20 minutes and an elimination half-life ranging from 12 to 16 hours. The half-life increases up to 41 hours in patients with severe impairment of renal function. Clonidine has a total clearance of 177 mL/min and a renal clearance of 102 mL/min. The apparent volume of distribution (Vz ) of clonidine is 197 L (2.9 L/kg). Clonidine crosses the placental barrier. It has been shown to cross the blood brain barrier in rats.

Following oral administration, about 40% to 60% of the absorbed dose is recovered in the urine as unchanged drug within 24 hours. About 50% of the absorbed dose is metabolized in the liver.

After removal of the clonidine transdermal system, clonidine plasma concentrations decline slowly with a half-life of approximately 20 hours.

INDICATIONS AND USAGE

Clonidine transdermal system is indicated in the treatment of hypertension. It may be employed alone or concomitantly with other antihypertensive agents.

CONTRAINDICATIONS

Clonidine transdermal system should not be used in patients with known hypersensitivity to clonidine or to any other component of the therapeutic system.

WARNINGS

All MedLibrary.org resources are included in as near-original form as possible, meaning that the information from the original provider has been rendered here with only typographical or stylistic modifications and not with any substantive alterations of content, meaning or intent.

This site is provided for educational and informational purposes only, in accordance with our Terms of Use, and is not intended as a substitute for the advice of a medical doctor, nurse, nurse practitioner or other qualified health professional.

Privacy Policy | Copyright © 2024. All Rights Reserved.