Clonidine
Mechanism :
Clonidine hydrochloride is a centrally acting antihypertensive agent. Clonidine also produces dose-dependent analgesia not antagonized by opiate antagonists. The analgesia is limited to the body regions innervated by the spinal segments where analgesic concentrations of clonidine are present. Clonidine is thought to produce analgesia at presynaptic and postjunctional alpha-2-adrenoceptors in the spinal cord by preventing pain signal transmission to the brain.
Indication :
- Hypertension
- ADHD
- Tourette syndrome
- Growth hormone secretion testing
Contraindications :
Contraindicated in porphyria, can intensify depression, abrupt withdrawal can result in rebound hypertension, therefore withdraw gradually.
Clonidine is contraindicated in patients with a history of sensitization or allergic reactions to clonidine. Epidural administration is contraindicated in the presence of an injection site infection, in patients on anticoagulant therapy and in those with a bleeding diathesis.
Dosing :
ADHD and Tourette syndrome:
Oral, initially 0.05 mg/24 hours OD increase by 0.05 mg once in 5-7 days upto max of 0.4 mg/kg/day in 3-4 divided doses.
Hypertension:
Oral, 5-10 microgram/kg/day in 2-4 divided doses, max 0.9 mg/kg/day, IV 2-6 microgram/kg as single dose.
Growth hormone secretion testing:
Oral 150 microgram/m² as single dose.
Adverse Effect :
Drowsiness, restlessness at night, dry mouth, bradycardia, QT prolongation, hypotension.
Interaction :
Tricyclic antidepressants and beta-blockers: Caution with tricyclic antidepressants and beta-blockers, as clonidine withdrawal may cause rebound hypertension in concurrent usage.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-50 | Dose as in normal renal function |
| 10-20 | Dose as in normal renal function |
| <10 | Dose as in normal renal function |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Not dialysed. Dose as in normal renal function |
| HD | Not dialysed. Dose as in normal renal function |
| HDF/High flux | Unknown dialysability. Dose as in normal renal function |
| CAV/VVHD | Unknown dialysability. Dose as in normal renal function |
Hepatic Dose :
Use with caution as clonidine undergoes hepatic metabolism. Watch for sedation and hypotension and adjust the dose accordingly.