Telmisartan Side Effects

Reported Telmisartan side effects

Boxed warning The US prescribing information for telmisartan tablets carries a boxed warning for fetal toxicity: drugs that act directly on the renin-angiotensin system can cause injury and death to the developing fetus, and the label says to stop telmisartan as soon as pregnancy is detected. Common effects in trials Telmisartan was studied for safety in more than 3,700 patients with hypertension. In placebo-controlled trials of 1,041 patients on telmisartan monotherapy for up to 12 weeks the overall rate of adverse events was similar to placebo. In the label's table covering 1,455 patients on telmisartan and 380 on placebo, the events at 1 percent or more and more frequent than placebo were upper respiratory tract infection (7 against 6 percent), back pain (3 against 1 percent), sinusitis (3 against 2 percent), diarrhea (3 against 2 percent) and pharyngitis (1 against 0 percent). Treatment was stopped for adverse events in 2.8 percent of 1,455 telmisartan patients and 6.1 percent of 380 placebo patients, and cough occurred at the same rate as placebo, 1.6 percent (US prescribing information for telmisartan tablets). In the cardiovascular outcome trials In TRANSCEND, over 4 years and 8 months of follow-up, 8.4 percent on telmisartan and 7.6 percent on placebo stopped for adverse events, and the only serious adverse events at least 1 percent more common on telmisartan were intermittent claudication (7 against 6 percent) and skin ulcer (3 against 2 percent) (US prescribing information for telmisartan tablets; PMID: 18757085). In ONTARGET, telmisartan caused less cough than ramipril (1.1 against 4.2 percent, p<0.001) and less angioedema (0.1 against 0.3 percent, p=0.01) but more symptomatic hypotension (2.6 against 1.7 percent, p<0.001) (PMID: 18378520). The combination with an ACE inhibitor Adding telmisartan to ramipril in ONTARGET produced no extra benefit and more harm: symptomatic hypotension in 4.8 percent against 1.7 percent on ramipril alone, syncope in 0.3 against 0.2 percent and renal dysfunction in 13.5 against 10.2 percent (PMID: 18378520). The renal analysis of the same trial found the composite of doubling of serum creatinine, dialysis or death in 14.5 percent of the combination group against 13.5 percent on ramipril (hazard ratio 1.09, 95% CI 1.01 to 1.18, p=0.037), and the largest fall in estimated glomerular filtration rate in the combination group (PMID: 18707986). This is the basis of the label's instruction to avoid combined use of renin-angiotensin system inhibitors. Postmarketing reports The label lists, from reports after approval: anemia, eosinophilia, thrombocytopenia, abdominal pain, diarrhea, dyspepsia, nausea, asthenia, chest pain, edema, fatigue, abnormal liver function, anaphylactic reaction, hypersensitivity, raised creatine phosphokinase and uric acid, hyperkalemia, hypoglycemia in diabetic patients, hyponatremia, myalgia, dizziness, headache, syncope, renal impairment including acute renal failure, erectile dysfunction, cough, angioedema with fatal outcome, drug eruption, urticaria, hypotension including postural hypotension, and rare cases of rhabdomyolysis (US prescribing information for telmisartan tablets). Animal toxicology There was no evidence of carcinogenicity when telmisartan was fed to mice and rats for up to 2 years at doses providing systemic exposures more than 100 times and more than 25 times the exposure in people taking the maximum recommended human dose, and genotoxicity assays, among them bacterial mutagenicity, a hamster cell gene mutation test, a human lymphocyte cytogenetic test and a mouse micronucleus test, showed no telmisartan-related effects (US prescribing information for telmisartan tablets).

When to continue, reduce, or stop Telmisartan

Telmisartan contraindications

Telmisartan carries a boxed warning for fetal toxicity. Use of drugs acting on the renin-angiotensin system in the second and third trimesters reduces fetal kidney function and raises fetal and neonatal illness and death, and the label says to stop telmisartan as soon as pregnancy is detected (US prescribing information for telmisartan tablets). Telmisartan is contraindicated in anyone with known hypersensitivity, such as anaphylaxis or angioedema, to telmisartan or any component of the product (US prescribing information for telmisartan tablets). The label contraindicates giving aliskiren together with telmisartan in patients with diabetes, and says to avoid the combination in renal impairment with a glomerular filtration rate below 60 mL/min/1.73 m2 (US prescribing information for telmisartan tablets). Dual blockade of the renin-angiotensin system with an angiotensin receptor blocker plus an ACE inhibitor or aliskiren raises the risk of hypotension, hyperkalemia and changes in kidney function, and the ONTARGET combination group had more renal dysfunction than either drug alone (US prescribing information for telmisartan tablets; PMID: 18378520, PMID: 18707986). In volume or salt depletion, symptomatic hypotension can follow the first doses in people with an activated renin-angiotensin system, for example those on high doses of diuretics, and the label says to correct the depletion first or start under close supervision (US prescribing information for telmisartan tablets). Potassium can rise (hyperkalemia), particularly in advanced renal impairment, heart failure, renal replacement therapy, or with potassium supplements, potassium-sparing diuretics or potassium-containing salt substitutes (US prescribing information for telmisartan tablets). Most telmisartan leaves the body in bile, so clearance is reduced and bioavailability approaches 100 percent in biliary obstruction or hepatic insufficiency; the label also warns of oliguria, progressive azotemia and rarely acute renal failure in people whose kidney function depends on the renin-angiotensin-aldosterone system (US prescribing information for telmisartan tablets). The label advises a nursing woman not to breastfeed during treatment with telmisartan, because of the potential for hypotension, hyperkalemia and renal impairment in the infant; telmisartan is present in the milk of lactating rats (US prescribing information for telmisartan tablets). Safety and effectiveness in children (patients under 18) have not been established and telmisartan pharmacokinetics have not been studied in that age group (US prescribing information for telmisartan tablets).

Why vendor quality drives Telmisartan side-effect frequency

Research-compound communities consistently report that adverse-event frequency tracks with source quality. Three reasons: (1) impurity profiles vary by lab (residual synthesis byproducts can trigger reactions); (2) mislabeled mass means actual dose can be 50-150% of stated dose; (3) reconstitution-grade water and capping methodology affect long-term storage stability. COA-verified vendors with published HPLC data minimize all three failure modes. Check a vendor's COA record and Trust Score before you buy.

Telmisartan side effects FAQ

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