Effects of telmisartan on renal excretory function in conscious dogs

Single-dose pharmacokinetics of telmisartan oral solution and effect of feeding in dogs

Telmisartan is an angiotensin II receptor blocker that has great potential to improve the treatment of hypertension, proteinuria, and cardiovascular disease in dogs. A feline-approved telmisartan oral solution (TOS) is available, but this formulation has not been evaluated in dogs. The aims of this study were to establish the pharmacokinetics of telmisartan administered as TOS and determine the effect of feeding on drug absorption in dogs. In a cross-over design, seven healthy dogs received 1 mg/kg telmisartan orally as TOS with or without food and underwent serial measurement of plasma telmisartan concentrations over 24 h. Bioequivalence of TOS administered with vs. without food was assessed by the 90% confidence interval method for maximum concentration (C_max ), and the observed and extrapolated areas under the curve (AUC_0-t and AUC_0-∞ ). The mean ratios of these parameters were 0.97 (CI 0.74-1.27), 0.92 (0.81-1.03), and 0.90 (0.82-1.00), respectively. Feeding methods were not bioequivalent based on C_max due to interindividual variation. These results suggest that TOS can be given to dogs with or without food but should be administered in the same way consistently. Additional pharmacokinetic and pharmacodynamic studies are warranted to confirm this recommendation and establish the therapeutic targets for telmisartan in dogs.

Telmisartan as an add-on treatment for dogs with refractory idiopathic epilepsy: a nonrandomized, uncontrolled, open-label clinical trial

OBJECTIVE

To evaluate the effect on seizure frequency of add-on telmisartan treatment in dogs with refractory idiopathic epilepsy.

ANIMALS

11 client-owned dogs with idiopathic epilepsy and ≥ 2 generalized seizures/mon that were currently being treated with ≥ 2 antiepileptic drugs.

PROCEDURES

Telmisartan was administered at a dosage of 0.25 to 1 mg/kg, PO, every 12 hours for 4 to 16 months. Seizure frequencies before and during telmisartan treatment were recorded.

RESULTS

10 dogs completed the 4-month treatment protocol. One dog was excluded owing to a transient increase in serum creatinine concentration; no adverse effects of telmisartan were observed in the remaining 10 dogs. A reduction in seizure frequency greater than an estimated expected placebo effect of 30% was evident in 7 of the 10 dogs. Long-term (12 to 16 months) follow-up information was available for 6 dogs, of which 4 had a further reduction in seizure frequency. Differences in seizure frequency were not statistically significant. No significant difference was found in serum phenobarbital concentration throughout the treatment period in the 7 dogs that were tested.

CLINICAL RELEVANCE

Telmisartan has the potential to reduce seizure frequency when administered as an add-on antiepileptic drug in dogs with refractory idiopathic epilepsy. A randomized, double-blind, placebo-controlled trial is needed to determine the true efficacy of telmisartan. On the basis of our results, a sample size of 54 dogs with refractory idiopathic epilepsy would be needed.

Effect of telmisartan, angiotensin-converting enzyme inhibition, or both, on proteinuria and blood pressure in dogs

Background

The use of telmisartan (TEL), an angiotensin‐receptor blocker, for the control of systemic hypertension and proteinuria in dogs has not been reported extensively in a clinical setting.

Objectives

To determine the effects of an angiotensin‐converting enzyme inhibitor (ACEi) alone, ACEi in combination with TEL, or TEL alone on systolic blood pressure and proteinuria in dogs with protein losing nephropathy (PLN).

Animals

Forty‐two client‐owned dogs being treated for PLN.

Methods

Retrospective observational study of medical records of dogs at a university teaching hospital from 2012 to 2018 with the use of benazepril or enalapril alone, TEL alone, or both modalities for the management of PLN. Noninvasive blood pressure and urine protein to creatinine ratio (UPC) were compared among the treatment groups over time. A multivariable mixed‐effects linear regression model followed by post hoc analysis was used to estimate the marginal means and differences between the treatment groups.

Results

In comparison to group ACEi alone, combination treatment of an ACEi with TEL significantly reduced (P = .007) systolic blood pressure by 13 mm Hg (95% confidence interval [95% CI]: 4‐22 mm Hg). Angiotensin‐converting enzyme inhibitor + TEL in comparison to ACEi alone showed significant (P = .01) reduction in UPC of 2.5 (95% CI: 0.6‐4.4). The UPC of group ACEi + TEL was significantly lower (P = .01) in comparison to TEL alone by 3.8 (95% CI: 0.8‐6.8).

Conclusions and Clinical Importance

Telmisartan can be used to treat systemic hypertension and proteinuria in dogs.

The effect of telmisartan on the ventricular systolic function in dogs with experimental supraventricular tachyarrhythmia

Maintaining a good ventricular systolic function is important in the long-term therapy of dogs with supraventricular tachyarrhythmia (SVTA). The objective of this study was to evaluate the inhibitory effect of telmisartan on myocardial injury and the resulting ventricular systolic dysfunction in a canine model of SVTA. A total of 14 dogs were randomly assigned to a Telmisartan (oral telmisartan, 1.0 mg/kg daily, n=7) or a Control (no drug administration, n=7) group; the duration of rapid atrial pacing (RAP) was 3 weeks for both groups. The cardiac troponin I (cTnI) concentration in the Control group was significantly increased after 3 weeks compared to that before RAP initiation (baseline), but no significant difference was observed in the Telmisartan group. Moreover, the cTnI concentration at 3 weeks was significantly lower in the Telmisartan group than in the Control group. The left ventricular fractional shortening was significantly decreased at 3 weeks compared to that at baseline in both groups. However, fractional shortening at 3 weeks was significantly higher in the Telmisartan group than in the Control group. The cardiac output values in the Control group were significantly decreased at 3 weeks compared with those at baseline, but no significant difference was observed in the Telmisartan group. This study demonstrates that telmisartan inhibits the reduction in ventricular systolic function and prevents myocardial injury in a canine model of SVTA. Therefore, telmisartan is suggested as a novel treatment for canine SVTA.

Angiotensin II type 1 receptor antagonists in animal models of vascular, cardiac, metabolic and renal disease

We have reviewed the effects of angiotensin II type 1 receptor antagonists (ARBs) in various animal models of hypertension, atherosclerosis, cardiac function, hypertrophy and fibrosis, glucose and lipid metabolism, and renal function and morphology. Those of azilsartan and telmisartan have been included comprehensively whereas those of other ARBs have been included systematically but without intention of completeness. ARBs as a class lower blood pressure in established hypertension and prevent hypertension development in all applicable animal models except those with a markedly suppressed renin-angiotensin system; blood pressure lowering even persists for a considerable time after discontinuation of treatment. This translates into a reduced mortality, particularly in models exhibiting marked hypertension. The retrieved data on vascular, cardiac and renal function and morphology as well as on glucose and lipid metabolism are discussed to address three main questions: 1. Can ARB effects on blood vessels, heart, kidney and metabolic function be explained by blood pressure lowering alone or are they additionally directly related to blockade of the renin-angiotensin system? 2. Are they shared by other inhibitors of the renin-angiotensin system, e.g. angiotensin converting enzyme inhibitors? 3. Are some effects specific for one or more compounds within the ARB class? Taken together these data profile ARBs as a drug class with unique properties that have beneficial effects far beyond those on blood pressure reduction and, in some cases distinct from those of angiotensin converting enzyme inhibitors. The clinical relevance of angiotensin receptor-independent effects of some ARBs remains to be determined.

Telmisartan/hydrochlorothiazide in the treatment of hypertension

Telmisartan blocks the detrimental actions of angiotensin II mediated via the angiotensin type 1 receptor. Unique features of telmisartan are high lipophilicity and a long terminal elimination half-life (~ 24 h). Telmisartan/hydrochlorothiazide is indicated for hypertensive patients unable to achieve target blood pressure with either monotherapy. Fixed-dose combination tablets containing telmisartan 40 or 80 mg and hydrochlorothiazide 12.5 mg are widely available; in addition, telmisartan/hydrochlorothiazide 80/25 mg is available in the USA. Telmisartan/hydrochlorothiazide is superior to losartan/hydrochlorothiazide and valsartan/hydrochlorothiazide in maintaining blood pressure control in the risky early morning hours at the end of the dosing interval. Furthermore, telmisartan/ hydrochlorothiazide provides superior 24-h mean blood pressure reduction and is better tolerated than amlodipine/hydrochlorothiazide in elderly patients with predominantly systolic hypertension. Telmisartan has the potential to confer additional reno- and cardioprotection to that due to blood pressure control. The cardioprotective activity of renin–angiotensin system blockade with telmisartan alone and in combination with ramipril is currently being evaluated in the ONgoing Telmisartan Alone and in combination with Ramipril Global Endpoint Trial (ONTARGET) and the Telmisartan Randomized AssessmeNt Study in aCE iNtolerant subjects with cardiovascular Disease (TRANSCEND). In total, 31,546 patients have been enrolled worldwide and are being followed for up to 5.5 years.

Telmisartan: a review of its use in hypertension

Telmisartan is an angiotensin II receptor antagonist that is highly selective for type 1 angiotensin II receptors. It was significantly more effective than placebo in large (n >100), double-blind, randomised, multicentre clinical trials in patients with mild to moderate hypertension. Telmisartan 20 to 160 mg once daily produced mean reductions in supine trough systolic blood pressure and diastolic blood pressure of up to 15.5 and 10.5 mm Hg, respectively. Maximum blood pressure reduction occurred with a dosage of 40 to 80 mg/day. Telmisartan 40 to 120 mg/day was as effective as amlodipine 5 to 10 mg/day or atenolol 50 to 100 mg/day in dose-titration studies. Telmisartan 20 to 160 mg/day was generally similar in efficacy to enalapril 5 to 20 mg/day or lisinopril 10 to 40 mg/day in both titration-to-response and other studies. Hydrochlorothiazide was coadministered in most of the titration-to-response studies if patients remained hypertensive. Telmisartan 80 mg/day was more effective than submaximal dosages of losartan (50 mg/day) or valsartan (80 mg/day) and was as effective as a fixed-dose combination of losartan 50 mg plus hydrochlorothiazide 12.5 mg over the last 6 hours of the dosage interval and the whole 24-hour postdose interval. In patients with severe hypertension, telmisartan 80 to 160 mg/day was as effective as enalapril 20 to 40 mg/day (both agents could be titrated and combined sequentially with hydrochlorothiazide 25 mg and amlodipine 5 mg). The addition of hydrochlorothiazide to telmisartan was more effective than each agent alone at lowering blood pressure in patients with hypertension. Telmisartan was well tolerated in patients with mild to moderate hypertension and was significantly less likely to cause persistent, dry cough than lisinopril.

CONCLUSION

Telmisartan is an effective antihypertensive agent with a tolerability profile similar to that of placebo. Comparative data have shown telmisartan to be as effective as other major classes of antihypertensive agents at lowering blood pressure. Compared with lisinopril, telmisartan is associated with a significantly lower incidence of dry, persistent cough. Therefore, telmisartan is a useful therapeutic option in the management of patients with hypertension.