Telmisartan; Uses, Dosage, Side Effects, Interaction, Pregnancy

Telmisartan is an angiotensin II receptor antagonist (ARB) used in the management of hypertension. Generally, angiotensin II receptor blockers (ARBs) such as telmisartan bind to the angiotensin II type 1 (AT1) receptors with high affinity, causing inhibition of the action of angiotensin II on vascular smooth muscle, ultimately leading to a reduction in arterial blood pressure.

Mechanism of Action of Telmisartan

Telmisartan interferes with the binding of angiotensin II to the angiotensin II AT₁-receptor by binding reversibly and selectively to the receptors in vascular smooth muscle and the adrenal gland. As angiotensin II is a vasoconstrictor, which also stimulates the synthesis and release of aldosterone, blockage of its effects results in decreases in systemic vascular resistance. Telmisartan does not inhibit the angiotensin converting enzyme, other hormone receptors, or ion channels. Studies also suggest that telmisartan is a partial agonist of PPARγ, which is an established target for antidiabetic drugs. This suggests that telmisartan can improve carbohydrate and lipid metabolism, as well as control insulin resistance without causing the side effects that are associated with full PPARγ activators.Angiotensin II is formed from angiotensin I in a reaction catalyzed by angiotensin-converting enzyme (ACE, kininase II). Angiotensin II is the principal pressor agent of the renin-angiotensin system, with effects that include vasoconstriction, stimulation of synthesis and release of aldosterone, cardiac stimulation, and renal reabsorption of sodium. Telmisartan works by blocking the vasoconstrictor and aldosterone secretory effects of angiotensin II.

or

Angiotensin II is formed from angiotensin I in a reaction catalyzed by angiotensin-converting enzyme (ACE, kininase II). Angiotensin II is the principal pressor agent of the renin-angiotensin system, with effects that include vasoconstriction, stimulation of synthesis and release of aldosterone, cardiac stimulation, and renal reabsorption of sodium. Telmisartan blocks the vasoconstrictor and aldosterone-secreting effects of angiotensin II by selectively blocking the binding of angiotensin II to the AT1 receptor in many tissues, such as vascular smooth muscle and the adrenal gland. Its action is therefore independent of the pathways for angiotensin II synthesis. There is also an AT2 receptor found in many tissues, but AT2 is not known to be associated with cardiovascular homeostasis. Telmisartan has much greater affinity (>3,000 fold) for the AT1 receptor than for the AT2 receptor. Blockade of the renin-angiotensin system with ACE inhibitors, which inhibit the biosynthesis of angiotensin II from angiotensin I, is widely used in the treatment of hypertension. ACE inhibitors also inhibit the degradation of bradykinin, a reaction also catalyzed by ACE. Because telmisartan does not inhibit ACE (kininase II), it does not affect the response to bradykinin. Whether this difference has clinical relevance is not yet known. Telmisartan does not bind to or block other hormone receptors or ion channels known to be important in cardiovascular regulation. Blockade of the angiotensin II receptor inhibits the negative regulatory feedback of angiotensin II on renin secretion, but the resulting increased plasma renin activity and angiotensin II circulating levels do not overcome the effect of telmisartan on blood pressure.

Indications of Telmisartan

• Cardiovascular Events
• Diabetic Nephropathies
• Heart Failure, 
• High Blood Pressure (Hypertension)
• Cardiovascular Risk Reduction
• Prevention of Cardiovascular Disease
• Diabetic Kidney Disease
• Diabetic Nephropathies
• Heart Failure, 
• High Blood Pressure (Hypertension)
• Marfan Syndrome
• Strokes
• Treatment of uncomplicated hypertension,
• Treatment of essential hypertension in adults.
• Reduction of cardiovascular morbidity in adults with
• Manifest atherothrombotic cardiovascular disease (history of coronary heart disease, stroke, or peripheral arterial disease) or
• Type 2 diabetes mellitus with documented target organ damage
• Used alone or in combination with other classes of antihypertensives for the treatment of hypertension. Also used in the treatment of diabetic nephropathy in hypertensive patients with type 2 diabetes mellitus, as well as the treatment of congestive heart failure (only in patients who cannot tolerate ACE inhibitors).

Therapeutic Indications of Telmisartan

• Hypertension: Treatment of essential hypertension in adults.
• Cardiovascular prevention: Reduction of cardiovascular morbidity in adults with:manifest atherothrombotic cardiovascular disease (history of coronary heart disease, stroke, or peripheral arterial disease) or type 2 diabetes mellitus with documented target organ damage
• Hypertension
• Treatment of essential hypertension in adults.
• Cardiovascular prevention
• Reduction of cardiovascular morbidity in patients with:

Contra Indications of Telmisartan

Dosage of Telmisartan

Strengths: 20 mg, 40 mg, 80 mg

• The typical starting dose is 40 mg, taken by mouth, once per day.
• The maintenance dose is 20–80 mg, taken by mouth, once per day.

Hypertension

• Initial dose: 40 mg orally once a day
• Maintenance dose: 40 to 80 mg orally once a day

Cardiovascular Risk Reduction

• 80 mg orally once a day

Side Effects of Telmisartan

The most common

• Dry cough
• Dizziness and light-headedness due to low blood pressure
• Fatigue, especially in the early stages
• Mouth dryness in the early stages
• The most commonrn (a burning feeling in the chest, behind the breastbone or gullet)
• Abdominal or stomach pain
• Constipation
• Nausea ,vomiting,
• painful or swollen gums
• numbness or heavy feeling in the jaw
• dull, aching pain in the hip, groin, or thigh
• stomach pain,
• headache,
• reversible hair loss or thinning, and
• fever.

Common

• chills or fever
• headache, severe and throbbing
• joint or back pain
• muscle aching or cramping
• muscle pains or stiffness
• chest pressure or squeezing pain in chest
• excessive sweating
• sudden drowsiness or need to sleep
• coughing up blood
• liver problems–nausea, upper stomach pain, itching, tired feeling, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes)
• decreased amount of urine

Rare

• Anxiety
• change in vision
• chest pain or tightness
• confusion
• cough
• Agitation
• arm, back, or jaw pain
• blurred vision
• chest pain or discomfort
• convulsions
• extra heartbeats
• hallucinations
• headache
• irritability
• lightheadedness
• cold and clammy skin
• fast and shallow breathing
• swelling of your feet, legs, or hands purple spot on your skin caused by internal bleeding
• fast or abnormal heart rate or palpitations
• loss of appetite
• lower back, side, or stomach pain
• mental depression
• muscle pain or cramps
• Swelling of your feet or ankles
• Shortness of breath
• Nausea, fever, dark urine, loss of appetite
• Depression

Drug Interactions of Telmisartan

Telmisartan may interact with following drugs, supplyments, & may change the efficacy of drugs

• angiotensin converting enzyme inhibitors (ACEIs; captopril, enalapril, ramipril)
• benzodiazepines (e.g., clonazepam, diazepam, lorazepam)
• beta-blockers (e.g., atenolol, metoprolol, propranolol)
• carbamazepine
• cimetidine
• cyclosporine
• dasatinib
• dexamethasone
• duloxetine
• asthma medications (e.g., theophylline)
• nonsteroidal anti-inflammatory medications (NSAIDs; e.g., indomethacin, naproxen)
• oral diabetes medications (e.g., metformin, pioglitazone)
• pentoxyifylline
• monoamine oxidase (MAO) inhibitors (e.g., phenelzine, selegiline, )
• other beta-blockers (e.g., propranolol, metoprolol)
• oxtriphylline
• verapamil
• imatinib
• imipramine
• macrolide antibiotics (e.g., clarithromycin, erythromycin)
• monoamine oxidase inhibitors (MAOIs; e.g., phenelzine, rasagiline, selegiline, )
• pentoxifylline
• phenytoin
• phosphodiesterase 5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
• quetiapine
• sertraline
• tetracycline
• theophylline
• tocilizumab
• warfarin

Pregnancy & Lactation of Telmisartan

Pregnancy

Angiotensin II receptor antagonists should not be initiated during pregnancy. Unless continued AIIRA therapy is considered essential, patients planning pregnancy should be changed to alternative antihypertensive treatments which have an established safety profile for use in pregnancy. When pregnancy is diagnosed, treatment with AIIRAs should be stopped immediately, and, if appropriate, alternative therapy should be started