Triamterene

Triamterene

Systematic (IUPAC) name
6-phenylpteridine-2,4,7-triamine
Clinical data
Trade names	Dyrenium
AHFS/Drugs.com	monograph
MedlinePlus	a682337
Pregnancy cat.	D(US)
Legal status	℞-only (US)
Routes	oral
Pharmacokinetic data
Bioavailability	30-70%
Protein binding	67%
Metabolism	conjugated to hydroxytriamterene
Half-life	1-2 hours, active metabolite 3 hours
Excretion	renal <50%, 21% unchanged
Identifiers
CAS number	396-01-0 Y
ATC code	C03DB02
PubChem	CID 5546
DrugBank	APRD00079
ChemSpider	5345 Y
UNII	WS821Z52LQ Y
KEGG	D00386 N
ChEMBL	CHEMBL585 Y
Chemical data
Formula	C12H11N7
Mol. mass	253.263 g/mol
InChI InChI=1S/C12H11N7/c13-9-7(6-4-2-1-3-5-6)16-8-10(14)18-12(15)19-11(8)17-9/h1-5H,(H6,13,14,15,17,18,19) Y Key:FNYLWPVRPXGIIP-UHFFFAOYSA-N Y
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Triamterene (trade name Dyrenium) is a potassium-sparing diuretic used in combination with thiazide diuretics for the treatment of hypertension and edema.

Mechanism of action

Triamterene directly blocks the epithelial sodium channel^[1] (ENaC) on the lumen side of the kidney collecting tubule. Other diuretics cause a decrease in the sodium concentration of the forming urine due to the entry of sodium into the cell via the ENaC, and the concomitant exit of potassium from the principal cell into the forming urine. Blocking ENaC prevents this from happening. Amiloride works in the same way. Sodium channel blockers directly inhibit the entry of sodium into the sodium channels.

Side effects

Common side effects may include a depletion of sodium, folic acid and calcium, nausea, vomiting, diarrhea, headache, dizziness, fatigue, and dry mouth. Serious side effects may include heart palpitations, tingling/numbness, fever, chills, sore throat, rash, and back pain. Triamterene can also cause kidney stones through direct crystallization or by seeding calcium oxalate stones. Triamterene is best avoided in patients with chronic kidney disease due to the possibility of hyperkalemia. People using this drug should use salt substitute cautiously.^[2]

Triamterene may impart a blue fluorescent color to the urine.

Caution with certain disease states

Diabetes: Use with caution in patients with prediabetes or diabetes mellitus as there may be a change in glucose control.

Hepatic impairment: Use with caution in patients with severe hepatic dysfunction; in cirrhosis, avoid electrolyte and acid/base imbalances that might lead to hepatic encephalopathy.

Kidney stones: Use with caution in patients with kidney stones.

Use should be avoided if the creatinine clearance is less than 10 ml/minute.

Use in Ménière's disease

While there is a lack of randomized controlled trials evaluating the use of triamterene in the treatment of Ménière's disease, the typical treatment is 37.5 mg of triamterene with 25 mg of hydrochlorothiazide 1-2 capsules daily.^[3][4] This recommendation was given a grade of C (see http://www.aafp.org/afpsort.xml for information about the SORT evidence rating system).

References

1. ^ Busch AE, Suessbrich H, Kunzelmann K, et al. (September 1996). "Blockade of epithelial Na+ channels by triamterenes - underlying mechanisms and molecular basis". Pflugers Arch. 432 (5): 760–6. doi:10.1007/s004240050196. PMID 8772124. http://link.springer.de/link/service/journals/00424/bibs/6432005/64320760.htm. 
2. ^ LoSalt Advisory Statement (PDF)
3. ^ Swartz R, Longwell P. Treatment of Vertigo. Am Fam Physician 2005 Mar 15;71(6)1115-1122.
4. ^ Sloane PD, Coeytaux RR, Beck RS, Dallara J. Dizziness: state of science. Ann Intern Med. 2001 May 1;134 (9, part 2 suppl):823-832

External links

• http://www.losalt.com/docs/lo_salt_web_advice.pdf
• http://gsm.about.com/compact/showmono.asp?cpnum=1087&r=6078&monotype=full