Dosing and uses of Atacand HCT (candesartan-hydrochlorothiazide)
Adult dosage forms and strengths
triamterene/hydrochlorothiazide
capsule
- 37.5mg/25mg
- 50mg/25mg
tablet
- 37.5mg/25mg
- 75mg/50mg
Hypertension
1-2 tablets/capsules (37.5-50 mg triamterene and 25 mg HCTZ) PO qDay
1 tablet (75 mg triamterene and 50 mg HCTZ) PO qDay
Dosing considerations
- Monitor serum potassium
Edema
1-2 tablets/capsules (37.5-50 mg triamterene and 25 mg HCTZ) PO qDay
1 tablet (75 mg triamterene and 50 mg HCTZ) PO qDay
Dosing considerations
- Monitor serum potassium
Pediatric dosage forms and strengths
Safety and efficacy not established
Atacand HCT (candesartan-hydrochlorothiazide) adverse (side) effects
Frequency not defined
Triamterene
- Jaundice
- Weaknes
- Headache
- Azotemia
- Dizziness
- Fatigue
- Xerostomia
- Photosensitivity
- Rash
- Diarrhea
- Nausea
- Vomiting
- Hyperuricemia
- Hyper/hypokalemia
- Interstitial nephritis
Hydrochlorothiazide
- Hypotension
- Dizziness
- Vertigo
- Headache
- Alopecia
- Erythema multiforme
- Toxic epidermal necrolysis
- Stevens-Johnson syndrome
- Fever
- Hyperglycemia
- Anorexia
- Epigastric distress
- Glycosuria
- Hypokalemia
- Phototoxicity
Warnings
Balck Box Warning
Triamterene can cause hperkalemia in patients at risk including patients with renal dysfunction, diabetes mellitus, the severely ill, the elderly; monitor serum potassium levels at frequent intervals especially with any illness that may cause renal dysfunction or when dosages are changed
Contraindications
Hypersensitivity to triamterene, hydrochlorothiazide, or sulfonamides (hydrochlorothiazide is a sulfonamide)
Concomitant administration with potassium rich diets, or any other form of potassium supplementation
Chronic or significant renal insufficiency or significant renal impairment
Anuria
Hyperkalemia ≥5.5 mEq/L
Cautions
Acute transient myopia and acute angle-closure glaucoma have been reported, particularly with history of sulfonamide or penicillin allergy
Hydrochlorothiazide can cause electrolyte disturbances including hypokalemia, hypochloremic alkalosis, and hyponatremia
Photosensitization may occur
Use with caution in diabetes mellitus, hepatic impairment, gout, hypercalcemia, hypercholesterolemia, kidney stones, parathyroid disease, systemic lupus erythematosus, and renal impairment
Risk of cross-reaction in patients with allergy to sulfonylurea, sulfonamides, thiazides, loop diuretics, or carbonic anhydrase may occur
Pregnancy and lactation
Pregnancy category: C
Lactation: Not recommended; discontinue drug or do not nurse
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 Atacand HCT (candesartan-hydrochlorothiazide)
Mechanism of action
Triamterene: Has direct effect on renal distal tubule to inhibit Na+ reabsorption; inhibits Na/K-ATPase, decreases Ca++ , Mg++ and hydrogen excretion
Hydrochlorothiazide: Inhibits sodium reabsorption in distal renal tubules, resulting in increased excretion of water and of sodium, potassium, and hydrogen ions
Pharmacokinetics
Triamterene
- Half-Life: 1.5-2.5 hr
- Duration: 7-9 hr
- Onset: Initial effect: 2-4 hr
- Max effect: Diuresis: several days, HTN: 2-3 months
- Peak Plasma Time: 1.5-3 hr
- Bioavailability: 30-70%
- Protein Bound: 55-67%
- Metabolism: Liver
- Metabolites: Hydroxytriamterene sulfate (active)
- Excretion: Urine (21%)
- Dialyzable: Yes (hemodialysis)
Hydrochlorothiazide
- Onset: ~2 hr (diuresis); 3-4 days (hypertension)
- Peak plasma time: 1-2.5 hr
- Peak effect: 4-6 hr (diuresis)
- Bioavailability: 65-75%
- Protein bound: 40-68%
- Vd: 3.6-7.8 L/kg
- Minimally metabolized
- Half-life: 5.6-14.8 hr
- Dialyzable: No (hemodialysis)
- Excretion: Urine
