Dosing and uses of Clorpres (clonidine/chlorthalidone)
Adult dosage forms and strengths
clonidine/chlorthalidone
tablet
- 0.1mg/15mg
- 0.2mg/15mg
- 0.3mg/15mg
Hypertension
Not indicated for initial therapy
If the fixed dose combination represents the dose appropriate to the individual patient's needs, it may be more convenient than the separate components
Usual dose: 0.1 mg/15 mg PO qD -BId
Maximum: 0.6 mg/30 mg PO qd
Renal Impairment
Use caution in dosing/titrating patients with renal dysfunction
Cumulative effects of thiazides may develop with impaired renal function
Other Information
Combination may be substituted for the titrated individual components
Withdraw gradually over a period of 2-4 days
Sudden cessation of clonidine treatment has resulted in subjective symptoms such as nervousness, agitation and headache, accompanied or followed by a rapid rise in blood pressure and elevated catecholamine concentrations in the plasma
May need dosage reduction for geriatric patients
Pediatric dosage forms and strengths
<18 years: Safety/efficacy not established
Clorpres (clonidine/chlorthalidone) adverse (side) effects
Frequency not defined
No adverse effects specific to the combination have been observed; adverse effects limited to those previously reported with clonidine and chlorthalidone
Clonidine (common)
- Orthostatic hypotension
- Drowsiness
- Malaise
- Rash
- Anorexia, weight gain
- Dry mouth
- Nausea/vomiting
- Abnormal LFTs
Chlorthalidone (common)
- Hypotension, vasculitis
- Dizziness, headache, paresthesia, restlessness
- Photosensitivity, phototoxicity
- Constipation, diarrhea, loss of appetite, nausea, vomiting
- Electrolyte abnormalities, hyperglycemia, hyperuricemia
- Impotence
- Muscular spasticity
- Blurred vision, xanthopsia
Chlorthalidone (rare)
- Cardiac dysrhythmia
- Scaling eczema
- Stevens-Johnson syndrome, systemic lupus erythematosus, toxic epidermal necrolysis
- Disorder of hematopoietic structure
- Hepatotoxicity
- Pancreatitis
- Pulmonary edema
Warnings
Contraindications
anuria
hypersensitivity to either component or sulfonamides
Cautions
Bronchospastic disease
DM, fluid or electrolyte imbalance, hyperuricemia or gout, hypotension, SLe
History of depression
Liver disease
May aggravate digitalis toxicity
Patients allergic to sulfa may show cross-sensitivity
May impair ability to perform hazarous tasks
Risk of male sexual dysfunction
Renal impairment
Severe coronary insufficiency, recent MI, conduction disturbances, cerebrovascular disease, chronic renal failure, Raynaud's disease, thromboangiitis obliteran
Avoid abrupt withdrawal due to risk of rebound hypertension
Pregnancy and lactation
Pregnancy category: C
Lactation: excreted in breast milk, use caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Clorpres (clonidine/chlorthalidone)
Half-Life
clonidine: 12-16 hr
chlorthalidone: 40-89 hr
Absorption
chlorthalidone 65% bioavailability
Onset
clonidine: <1 hr
chlorthalidone: 2-6 hr
Duration
chlorthalidone: 72 hr
Vd
chlorthalidone: 3-13 L/kg
Peak Plasma Time
chlorthalidone: 1.5-6 hr
Protein Bound
chlorthalidone 75%
Metabolism
clonidine: liver
Metabolites: no clinically active metabolites
Clearance
chlorthalidone: total body clearance 53-145 mL/min
Excretion
clonidine: urine
chlorthalidone: urine 96%
Dialyzable
chlorthalidone HD: no
Mechanism of action
clonidine/chlorthalidone is a fixed-combination tablet that combines a central alpha-2 stimulator, clonidine and a diuretic, chlorthalidone
Clonidine produces central alpha 2-adrenergic stimulation, which results in a decreased sympathetic outflow to the heart, kidneys, and peripheral vasculature; this results in decreased peripheral vascular resistance, decreased systolic and diastolic blood pressure, and decreased heart rate
Chlorthalidone, a monosulfonamyl diuretic, inhibits Na & Cl reabsorption in cortical-diluting segment of ascending loop of Henle
