Semintra for cats Slowing chronic kidney disease.
Chronic kidney failure is a health problem whose incidence increases with age, affecting up to 33% of cats older than 15 years. Once diagnosed, life expectancy is between two and three years. Cats with long-term chronic kidney disease usually also suffer from proteinuria, and the onset of arterial hypertension is also not uncommon.
Semintra is a medicinal product used to reduce proteinuria and treat arterial hypertension in cats. A reduction in proteinuria is observed after only seven days from the start of treatment. In contrast to angiotensin-converting enzyme inhibitors, Semintra acts directly on the unwanted effects resulting from activation of the AT1 receptor while maintaining the beneficial effects associated with activation of the AT2 receptor.
Mechanism of action of Semintra
The active substance in Semintra is telmisartan, an angiotensin II receptor antagonist that inhibits the action of the hormone angiotensin II, which is a potent vasoconstrictor Telmisartan displaces angiotensin II from its binding sites in the AT1 receptor sub-type, selectively binding to this receptor. Moreover, this binding is long-lasting as telmisartan exhibits slow dissociation.
By blocking the receptor to which angiotensin II usually binds, telmisartan impedes the action of this hormone in the kidney and other organs, thereby inhibiting its effects on vasoconstriction, sodium and water retention and the increased synthesis of aldosterone. Thus, it enhances dilation of the blood vessels, which reduces blood pressure while also reducing the protein content of urine. As a result of this mechanism, kidney disease progression is slowed.
A study1 performed at the University of Georgia showed that administration of telmisartan is more beneficial than Benazepril for cats with kidney or cardiovascular disease as it controls systolic blood pressure better and is more effective after 24 hours.
Another study2 carried out at the Royal Veterinary College (London) also concluded that telmisartan is both safer and more effective than benazepril as regards decreasing the urea/creatinine ratio in urine.
It should be noted that telmisartan is absorbed rapidly, with peak plasma concentration being reached 0.5 hours after oral administration of 1 mg/kg. Absolute bioavailability was 33%.
Given that this substance is highly lipophilic and exhibits fast membrane permeability kinetics, it is readily distributed to the tissues. This compound has a half-life of 7.7 hours and is excreted almost exclusively in stools.
How is Semintra used in cats?
Semintra is a solution for oral administration available in two different concentrations: 4 mg/ml to reduce proteinuria and 10 mg/ml to treat arterial hypertension. However, it must be administered once daily.
The recommended dose for reducing proteinuria is 1 mg telmisartan per kg body weight. In the case of arterial hypertension, the initial dose is 2 mg telmisartan per kg body weight, although this can be reduced after 4 weeks of treatment.
It can be administered directly into the mouth or with a small quantity of food. Indeed, food consumption does not affect the total degree of absorption of telmisartan. However, it should not be mixed with other medicinal products as compatibility studies are not yet available.
What are the risks associated with Semintra for cats?
Mild gastrointestinal problems, such as vomiting and diarrhoea, are the most common side effects, although they are usually transitory and short-lasting. Regurgitation and soft stools have been reported in some cases.
Although not common, an increase in liver enzymes, which return to normal when treatment is suspended, may occur. A transitory hypotension may also be observed, in which case symptomatic treatment will need to be administered.
A slight decrease in erythrocyte count also tends to occur, therefore this parameter must be monitored throughout treatment. The safety and efficacy of Semintra in cats younger than 6 months is not known, therefore its use in pregnant or lactating animals is not recommended.
However, a study3 published at the International Feline Medicine Congress showed that 91% of cats treated with Semintra had improved after one month. Owners indicated that appetite was maintained or improved in 90% of cats, which is one of the main problems related to chronic kidney failure.
The renal diet in the treatment of chronic kidney failure
In addition to medical treatment, the renal diet is key to slowing the progress of chronic kidney failure in cats and improving their quality of life. It is normal to restrict protein and phosphate intake.
Any excess of phosphates consumed in the diet is excreted via the kidneys, which is dependent on glomerular filtration. As such, cats with chronic kidney failure are more likely to experience phosphate retention, hyperphosphataemia and renal osteodystrophy. Fewer proteins are provided by renal diets but they are of higher quality, contain fewer phosphates and are rich in potassium and B vitamins.