Avalide

Serious side effects have been reported with Avalide. See the "Avalide Precautions" section. 

Common side effects of Avalide include the following:

• chest pain
• tiredness (fatigue)
• flu symptoms
• retaining fluid/swelling (edema)
• fast heart rate (tachycardia)
• stomach (abdominal) pain
• indigestion/heartburn
• nausea/vomiting
• allergy
• muscle pain
• dizziness/dizziness upon standing
• abnormal changes in urination

This is not a complete list of Avalide side effects. Ask your doctor or pharmacist for more information. 

Tell your doctor if you have any side effect that bothers you or that does not go away.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088. 

Serious side effects have been reported with Avalide or its ingredients including the following:

• Harm to an unborn baby (fetal toxicity). Do not take Avalide if you are pregnant or will become pregnant.
• Allergic reactions. More likely with a history of allergic reactions. 
• Increase in liver function tests. Your doctor will monitor your labs. 
• An autoimmune disease in which the body's immune system mistakenly attacks healthy tissue (systemic lupus erythematosus)
• Imbalances in the levels of salts and fluids in your body (electrolyte and fluid imbalance). Tell your healthcare provider right away if you have some or all of the following symptoms:
  • dry mouth
  • thirst
  • weakness
  • drowsiness
  • restlessness
  • muscle pains or cramps
  • low blood pressure
  • low output of urine
  • fast heart rate
  • nausea
  • vomiting
• Increased levels of potassium. Your doctor will monitor your labs. 
• Increase levels of cholesterol and triglyceride. Your doctor will monitor your labs. 
• A condition of excess of uric acid in the blood (hyperuricemia)
• Painful joint(s) (gout)
• Decrease in kidney function. Your doctor may hold or stop Avalide if your kidney does not work as well.
• Increase in blood sugar in patients with diabetes. Your doctor may need to adjust your diabetes medication

Do not take Avalide if you:

• are allergic to Avalide or any of its ingredients or sulfonamide-derived drugs
• your kidneys do not produce urine (anuria)
• are a diabetic patient who is taking aliskiren

Take Avalide exactly as prescribed. 

• Avalide comes in a tablet form and is taken by mouth once daily with or without food. 
• If you miss a dose, take the missed dose as soon as you remember. If it is almost time for the next dose, skip the missed dose and take your next dose at the regular time. Do not take two doses of Avalide at the same time. 

Hydrochlorothiazide is a thiazide diuretic (water pill) that helps prevent your body from absorbing too much salt, which can cause fluid retention.

Irbesartan is an angiotensin II receptor antagonist. Irbesartan keeps blood vessels from narrowing, which lowers blood pressure and improves blood flow.

Hydrochlorothiazide and irbesartan is a combination medicine used to treat high blood pressure (hypertension).

Hydrochlorothiazide and irbesartan may also be used for purposes not listed in this medication guide.

Do not use if you are pregnant. If you become pregnant, stop taking this medicine and tell your doctor right away.

You should not use this medicine if you are unable to urinate, or if you are allergic to sulfa drugs.

If you have diabetes, do not use hydrochlorothiazide and irbesartan together with any medication that contains aliskiren (such as Tekturna or Tekamlo).

It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly. Blood and urine tests may be needed to check for unwanted effects.

Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant. If you think you have become pregnant while using this medicine, tell your doctor right away.

This medicine may cause dizziness, lightheadedness, or fainting, especially when you get up suddenly from a lying or sitting position. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy. If you feel dizzy, lie down so you do not faint. Then sit for a few moments before standing to prevent the dizziness from returning. If you faint, call your doctor right away.

Check with your doctor right away if you become sick while taking this medicine, especially if you have severe or continuing nausea, vomiting, or diarrhea. These conditions may cause you to lose too much water and lead to low blood pressure. You can also loose water by sweating, so drink plenty of water during exercise or in hot weather.

Check with your doctor immediately if blurred vision, difficulty with reading, eye pain, or any other change in vision occurs during or after treatment. This could be a sign of a serious eye problem. Your doctor will want you to have your eyes checked by an ophthalmologist (eye doctor).

This medicine may affect blood sugar levels. If you notice a change in the results of your blood or urine sugar tests, or if you have any questions, check with your doctor.

Ask your doctor before you use medicines, supplements, or salt substitutes that contain potassium.

Drinking alcohol or taking narcotic pain relievers or sleeping pills with this medicine may intensify feeling lightheaded, dizzy, or faint. Tell your doctor if you are drinking alcohol or using pain relievers or sleeping pills.

Do not take other medicines unless they have been discussed with your doctor. This especially includes over-the-counter (nonprescription) medicines for appetite control, asthma, colds, cough, hay fever, or sinus problems, since they may tend to increase your blood pressure.

• If you have an allergy to irbesartan, hydrochlorothiazide, or any other part of this medicine.
• If you are allergic to any drugs like this one, any other drugs, foods, or other substances. Tell your doctor about the allergy and what signs you had, like rash; hives; itching; shortness of breath; wheezing; cough; swelling of face, lips, tongue, or throat; or any other signs.
• If you are taking dofetilide.
• If you have kidney disease.
• If you are not able to pass urine.
• If you are taking a drug that has aliskiren in it and you also have high blood sugar (diabetes) or kidney problems. Check with your doctor or pharmacist if you are not sure if a drug you take has aliskiren in it.
• If you are breast-feeding or plan to breast-feed.

This is not a list of all drugs or health problems that interact with Avalide.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take this medicine with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
• Signs of high blood sugar like confusion, feeling sleepy, more thirst, more hungry, passing urine more often, flushing, fast breathing, or breath that smells like fruit.
• Signs of kidney problems like unable to pass urine, change in how much urine is passed, blood in the urine, or a big weight gain.
• Signs of fluid and electrolyte problems like mood changes, confusion, muscle pain or weakness, a heartbeat that does not feel normal, very bad dizziness or passing out, fast heartbeat, more thirst, seizures, feeling very tired or weak, not hungry, unable to pass urine or change in the amount of urine produced, dry mouth, dry eyes, or very bad upset stomach or throwing up.
• Chest pain.
• Swelling.
• This medicine can cause certain eye problems. If left untreated, this can lead to lasting eyesight loss. If eye problems happen, signs like change in eyesight or eye pain most often happen within hours to weeks of starting this medicine. Call your doctor right away if you have these signs.

Avalide® (irbesartan-hydrochlorothiazide) tablets are indicated for the treatment of hypertension.

Avalide may be used in patients whose blood pressure is not adequately controlled on monotherapy.

Avalide may also be used as initial therapy in patients who are likely to need multiple drugs to achieve their blood pressure goals.

The choice of Avalide as initial therapy for hypertension should be based on an assessment of potential benefits and risks.

Patients with stage 2 (moderate or severe) hypertension are at relatively high risk for cardiovascular events (such as strokes, heart attacks, and heart failure), kidney failure, and vision problems, so prompt treatment is clinically relevant. The decision to use a combination as initial therapy should be individualized and may be shaped by considerations such as the baseline blood pressure, the target goal, and the incremental likelihood of achieving goal with a combination compared with monotherapy.

Data from Studies V and VI [see Clinical Studies (14.2)] provide estimates of the probability of reaching a blood pressure goal with Avalide compared to irbesartan or HCTZ monotherapy. The relationship between baseline blood pressure and achievement of a SeSBP <140 or <130 mmHg or SeDBP <90 or <80 mmHg in patients treated with Avalide compared to patients treated with irbesartan or HCTZ monotherapy are shown in Figures 1a through 2b.

The above graphs provide a rough approximation of the likelihood of reaching a targeted blood pressure goal (e.g., Week 8 sitting systolic blood pressure ≤140 mmHg) for the treatment groups. The curve of each treatment group in each study was estimated by logistic regression modeling from all available data of that treatment group. The estimated likelihood at the right tail of each curve is less reliable due to small numbers of subjects with high baseline blood pressures.

For example, a patient with a blood pressure of 180/105 mmHg has about a 25% likelihood of achieving a goal of <140 mmHg (systolic) and 50% likelihood of achieving <90 mmHg (diastolic) on irbesartan alone (and lower still likelihoods on HCTZ alone).

The likelihood of achieving these goals on Avalide rises to about 40% (systolic) or 70% (diastolic).

Irbesartan

No data are available in regard to overdosage in humans. However, daily doses of 900 mg for 8 weeks were well tolerated. The most likely manifestations of overdosage are expected to be hypotension and tachycardia; bradycardia might also occur from overdose. Irbesartan is not removed by hemodialysis.

To obtain up-to-date information about the treatment of overdosage, a good resource is a certified regional Poison Control Center. Telephone numbers of certified Poison Control Centers are listed in the Physicians' Desk Reference (PDR). In managing overdose, consider the possibilities of multiple-drug interactions, drug-drug interactions, and unusual drug kinetics in the patient.

Laboratory determinations of serum levels of irbesartan are not widely available, and such determinations have, in any event, no established role in the management of irbesartan overdose.

Acute oral toxicity studies with irbesartan in mice and rats indicated acute lethal doses were in excess of 2000 mg/kg, about 25- and 50-fold the MRHD (300 mg) on a mg/m2 basis, respectively.

Hydrochlorothiazide

The most common signs and symptoms of overdose observed in humans are those caused by electrolyte depletion (hypokalemia, hypochloremia, hyponatremia) and dehydration resulting from excessive diuresis. If digitalis has also been administered, hypokalemia may accentuate cardiac arrhythmias. The degree to which hydrochlorothiazide is removed by hemodialysis has not been established. The oral LD50 of hydrochlorothiazide is greater than 10 g/kg in both mice and rats.

Mechanism of Action

Irbesartan

Angiotensin II is a potent vasoconstrictor formed from angiotensin I in a reaction catalyzed by angiotensin-converting enzyme (ACE, kininase II). Angiotensin II is the principal pressor agent of the RAS and also stimulates aldosterone synthesis and secretion by adrenal cortex, cardiac contraction, renal resorption of sodium, activity of the sympathetic nervous system, and smooth muscle cell growth. Irbesartan blocks the vasoconstrictor and aldosterone-secreting effects of angiotensin II by selectively binding to the AT1 angiotensin II receptor. There is also an AT2 receptor in many tissues, but it is not involved in cardiovascular homeostasis.

Irbesartan is a specific competitive antagonist of AT1 receptors with a much greater affinity (more than 8500-fold) for the AT1 receptor than for the AT2 receptor, and no agonist activity.

Blockade of the AT1 receptor removes the negative feedback of angiotensin II on renin secretion, but the resulting increased plasma renin activity and circulating angiotensin II do not overcome the effects of irbesartan on blood pressure.

Irbesartan does not inhibit ACE or renin or affect other hormone receptors or ion channels known to be involved in the cardiovascular regulation of blood pressure and sodium homeostasis. Because irbesartan does not inhibit ACE, it does not affect the response to bradykinin; whether this has clinical relevance is not known.

Hydrochlorothiazide

Hydrochlorothiazide is a thiazide diuretic. Thiazides affect the renal tubular mechanisms of electrolyte reabsorption, directly increasing excretion of sodium and chloride in approximately equivalent amounts. Indirectly, the diuretic action of hydrochlorothiazide reduces plasma volume, with consequent increases in plasma renin activity, increases in aldosterone secretion, increases in urinary potassium loss, and decreases in serum potassium. The renin-aldosterone link is mediated by angiotensin II, so coadministration of an angiotensin II receptor antagonist tends to reverse the potassium loss associated with these diuretics.

The mechanism of the antihypertensive effect of thiazides is not fully understood.

Pharmacodynamics

Irbesartan

In healthy subjects, single oral irbesartan doses of up to 300 mg produced dose-dependent inhibition of the pressor effect of angiotensin II infusions. Inhibition was complete (100%) 4 hours following oral doses of 150 mg or 300 mg and partial inhibition was sustained for 24 hours (60% and 40% at 300 mg and 150 mg, respectively).

In hypertensive patients, angiotensin II receptor inhibition following chronic administration of irbesartan causes a 1.5- to 2-fold rise in angiotensin II plasma concentration and a 2- to 3-fold increase in plasma renin levels. Aldosterone plasma concentrations generally decline following irbesartan administration, but serum potassium levels are not significantly affected at recommended doses.

In hypertensive patients, chronic oral doses of irbesartan (up to 300 mg) had no effect on glomerular filtration rate, renal plasma flow or filtration fraction. In multiple dose studies in hypertensive patients, there were no clinically important effects on fasting triglycerides, total cholesterol, HDL-cholesterol, or fasting glucose concentrations. There was no effect on serum uric acid during chronic oral administration and no uricosuric effect.

Hydrochlorothiazide

After oral administration of hydrochlorothiazide, diuresis begins within 2 hours, peaks in about 4 hours and lasts about 6 to 12 hours.

Drug Interactions

Hydrochlorothiazide

Alcohol, barbiturates, or narcotics: Potentiation of orthostatic hypotension may occur.

Skeletal muscle relaxants: Possible increased responsiveness to muscle relaxants such as curare derivatives.

Corticosteroids, ACTH intensified electrolyte depletion, particularly hypokalemia.

Pressor amines (e.g., norepinephrine) possible decreased response to pressor amines but not sufficient to preclude their use.

Pharmacokinetics

Irbesartan

Irbesartan is an orally active agent that does not require biotransformation into an active form. The oral absorption of irbesartan is rapid and complete with an average absolute bioavailability of 60% to 80%. Following oral administration of irbesartan, peak plasma concentrations of irbesartan are attained at 1.5 to 2 hours after dosing. Food does not affect the bioavailability of irbesartan.

Irbesartan exhibits linear pharmacokinetics over the therapeutic dose range.

The terminal elimination half-life of irbesartan averaged 11 to 15 hours. Steady-state concentrations are achieved within 3 days. Limited accumulation of irbesartan (<20%) is observed in plasma upon repeated once-daily dosing.

Hydrochlorothiazide

When plasma levels have been followed for at least 24 hours, the plasma half-life has been observed to vary between 5.6 and 14.8 hours.

Metabolism and Elimination

Irbesartan

Irbesartan is metabolized via glucuronide conjugation and oxidation. Following oral or intravenous administration of 14C-labeled irbesartan, more than 80% of the circulating plasma radioactivity is attributable to unchanged irbesartan. The primary circulating metabolite is the inactive irbesartan glucuronide conjugate (approximately 6%). The remaining oxidative metabolites do not add appreciably to irbesartan's pharmacologic activity.

Irbesartan and its metabolites are excreted by both biliary and renal routes. Following either oral or intravenous administration of 14C-labeled irbesartan, about 20% of radioactivity is recovered in the urine and the remainder in the feces, as irbesartan or irbesartan glucuronide.

In vitro studies of irbesartan oxidation by cytochrome P450 isoenzymes indicated irbesartan was oxidized primarily by 2C9; metabolism by 3A4 was negligible. Irbesartan was neither metabolized by, nor did it substantially induce or inhibit, isoenzymes commonly associated with drug metabolism (1A1, 1A2, 2A6, 2B6, 2D6, 2E1). There was no induction or inhibition of 3A4.

Hydrochlorothiazide

Hydrochlorothiazide is not metabolized but is eliminated rapidly by the kidney. At least 61% of the oral dose is eliminated unchanged within 24 hours.

Distribution

Irbesartan

Irbesartan is 90% bound to serum proteins (primarily albumin and α1-acid glycoprotein) with negligible binding to cellular components of blood. The average volume of distribution is 53 to 93 liters. Total plasma and renal clearances are in the range of 157 to 176 mL/min and 3.0 to 3.5 mL/min, respectively. With repetitive dosing, irbesartan accumulates to no clinically relevant extent.

Studies in animals indicate that radiolabeled irbesartan weakly crosses the blood-brain barrier and placenta. Irbesartan is excreted in the milk of lactating rats.

Hydrochlorothiazide

Hydrochlorothiazide crosses the placental but not the blood-brain barrier and is excreted in breast milk.

Pediatric

Irbesartan-hydrochlorothiazide pharmacokinetics have not been investigated in patients <18 years of age.

Gender

No gender-related differences in pharmacokinetics were observed in healthy elderly (age 65 to 80 years) or in healthy young (age 18 to 40 years) subjects. In studies of hypertensive patients, there was no gender difference in half-life or accumulation, but somewhat higher plasma concentrations of irbesartan were observed in females (11% to 44%). No gender-related dosage adjustment is necessary.

Geriatric

In elderly subjects (age 65 to 80 years), irbesartan elimination half-life was not significantly altered, but AUC and Cmax values were about 20% to 50% greater than those of young subjects (age 18 to 40 years). No dosage adjustment is necessary in the elderly.

Race

In healthy black subjects, irbesartan AUC values were approximately 25% greater than whites; there were no differences in Cmax values.

Renal Insufficiency

The pharmacokinetics of irbesartan were not altered in patients with renal impairment or in patients on hemodialysis. Irbesartan is not removed by hemodialysis. No dosage adjustment is necessary in patients with mild to severe renal impairment unless a patient with renal impairment is also volume depleted. [See Warnings and Precautions (5.2).]

Hepatic Insufficiency

The pharmacokinetics of irbesartan following repeated oral administration were not significantly affected in patients with mild to moderate cirrhosis of the liver. No dosage adjustment is necessary in patients with hepatic insufficiency.

Drug-Drug Interactions

No significant drug-drug pharmacokinetic (or pharmacodynamic) interactions have been found in interaction studies with hydrochlorothiazide, digoxin, warfarin, and nifedipine.

In vitro studies show significant inhibition of the formation of oxidized irbesartan metabolites with the known cytochrome CYP 2C9 substrates/inhibitors sulphenazole, tolbutamide, and nifedipine. However, in clinical studies the consequences of concomitant irbesartan on the pharmacodynamics of warfarin were negligible. Concomitant nifedipine or hydrochlorothiazide had no effect on irbesartan pharmacokinetics. Based on in vitro data, no interaction would be expected with drugs whose metabolism is dependent upon cytochrome P450 isoenzymes 1A1, 1A2, 2A6, 2B6, 2D6, 2E1, or 3A4.

In separate studies of patients receiving maintenance doses of warfarin, hydrochlorothiazide, or digoxin, irbesartan administration for 7 days had no effect on the pharmacodynamics of warfarin (prothrombin time) or the pharmacokinetics of digoxin. The pharmacokinetics of irbesartan were not affected by coadministration of nifedipine or hydrochlorothiazide.

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

• For oral dosage form (tablets):
  • For high blood pressure:
    • Adults—One tablet once a day. Your doctor may increase your dose if needed.
    • Children—Use and dose must be determined by your doctor.

Usual Adult Dose for Hypertension:

Initial therapy: Hydrochlorothiazide 12.5 mg-Irbesartan 150 mg orally once a day; may increase after 1 to 2 weeks.

Add-on/Replacement therapy: Hydrochlorothiazide 12.5 to 25 mg-Irbesartan 150 to 300 mg orally once a day

Maximum dose: Hydrochlorothiazide 25 mg-Irbesartan 300 mg orally once a day

Comments:
-The recommended doses in order of increasing mean effect are (hydrochlorothiazide-irbesartan): 12.5 mg-150 mg, 12.5 mg-300 mg, 25 mg-300 mg; the largest incremental effect will likely be from monotherapy to 12.5 mg-150 mg.
-Maximum antihypertensive effect is attained within 2 to 4 weeks after a change in dose.

Applies to hydrochlorothiazide / irbesartan: oral tablet

Along with its needed effects, hydrochlorothiazide / irbesartan may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking hydrochlorothiazide / irbesartan:

• Abdominal or stomach pain
• bloody or cloudy urine
• chest pain
• confusion
• difficult with breathing
• difficult, burning, or painful urination
• fast, pounding, or irregular heartbeat or pulse
• frequent urge to urinate
• lower back or side pain
• nausea or vomiting
• numbness or tingling in the hands, feet, or lips
• swelling
• weakness or heaviness of the legs

• Blurred vision
• convulsions
• dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
• loss of appetite
• muscle pain or cramps
• sweating
• unusual tiredness or weakness

• Dark-colored urine
• fever
• hives or welts, itching, or skin rash
• large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
• muscle spasms or stiffness
• upper right abdominal or stomach pain
• yellow eyes and skin

Some side effects of hydrochlorothiazide / irbesartan may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

• Headache
• sunburn

• Acid or sour stomach
• chills
• congestion
• cough
• diarrhea
• dryness or soreness of the throat
• joint pain
• sneezing
• stomach discomfort or upset
• tender, swollen glands in the neck
• trouble sleeping
• trouble swallowing