"What are angiotensin receptor blockers (ARBs) and how do they work?
The class of drugs called angiotensin receptor blockers (ARBs), as the class name suggests, are drugs that block the action of angiotensin. Specifically, ARBs preve"...
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Clinical Trials Experience
Because clinical studies are conducted under widely varying conditions, adverse reactions rates observed in the clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug and may not reflect the rates observed in practice. The adverse reaction information from clinical trials does, however, provide a basis for identifying the adverse events that appear to be related to drug use and for approximating rates.
Diovan HCT (valsartan and hydrochlorothiazide, USP) has been evaluated for safety in more than 5,700 patients, including over 990 treated for over 6 months, and over 370 for over 1 year. Adverse experiences have generally been mild and transient in nature and have only infrequently required discontinuation of therapy. The overall incidence of adverse reactions with Diovan HCT was comparable to placebo.
The overall frequency of adverse reactions was neither dose-related nor related to gender, age, or race. In controlled clinical trials, discontinuation of therapy due to side effects was required in 2.3% of valsartan-hydrochlorothiazide patients and 3.1% of placebo patients. The most common reasons for discontinuation of therapy with Diovan HCT were headache and dizziness.
The only adverse reaction that occurred in controlled clinical trials in at least 2% of patients treated with Diovan HCT and at a higher incidence in valsartan-hydrochlorothiazide (n=4372) than placebo (n=262) patients was nasopharyngitis (2.4% vs. 1.9%).
Dose-related orthostatic effects were seen in fewer than 1% of patients. In individual trials, a dose-related increase in the incidence of dizziness was observed in patients treated with Diovan HCT. Other adverse reactions that have been reported with valsartan-hydrochlorothiazide ( > 0.2% of valsartan-hydrochlorothiazide patients in controlled clinical trials) without regard to causality, are listed below:
General and Administration Site Conditions: Asthenia, chest pain, fatigue, peripheral edema and pyrexia
Investigations: Blood urea increased
Psychiatric: Anxiety and insomnia
Renal and Urinary: Pollakiuria
Reproductive System: Erectile dysfunction
Respiratory, Thoracic and Mediastinal: Dyspnea, cough, nasal congestion, pharyngolaryngeal pain and sinus congestion
Skin and Subcutaneous Tissue: Hyperhidrosis and rash
Other reported reactions seen less frequently in clinical trials included abnormal vision, anaphylaxis, bronchospasm, constipation, depression, dehydration, decreased libido, dysuria, epistaxis, flushing, gout, increased appetite, muscle weakness, pharyngitis, pruritus, sunburn, syncope, and viral infection.
Initial Therapy - Hypertension
In a clinical study in patients with severe hypertension (diastolic blood pressure ≥ 110 mmHg and systolic blood pressure ≥ 140 mmHg), the overall pattern of adverse reactions reported through six weeks of follow-up was similar in patients treated with Diovan HCT as initial therapy and in patients treated with valsartan as initial therapy. Comparing the groups treated with Diovan HCT (force-titrated to 320/25 mg) and valsartan (force-titrated to 320 mg), dizziness was observed in 6% and 2% of patients, respectively. Hypotension was observed in 1% of those patients receiving Diovan HCT and 0% of patients receiving valsartan. There were no reported cases of syncope in either treatment group. Laboratory changes with Diovan HCT as initial therapy in patients with severe hypertension were similar to those reported with Diovan HCT in patients with less severe hypertension [see Clinical Studies and DRUG INTERACTIONS].
In trials in which valsartan was compared to an ACE inhibitor with or without placebo, the incidence of dry cough was significantly greater in the ACE inhibitor group (7.9%) than in the groups who received valsartan (2.6%) or placebo (1.5%). In a 129-patient trial limited to patients who had had dry cough when they had previously received ACE inhibitors, the incidences of cough in patients who received valsartan, hydrochlorothiazide, or lisinopril were 20%, 19%, 69% respectively (p < 0.001).
Hydrochlorothiazide: Other adverse reactions not listed above that have been reported with hydrochlorothiazide, without regard to causality, are listed below:
Body As A Whole: weakness;
respiratory distress including pneumonitis and pulmonary edema, anaphylactic reactions;
Musculoskeletal: muscle spasm;
Nervous System/Psychiatric: restlessness;
Skin: erythema multiforme including Stevens-Johnson syndrome, exfoliative dermatitis including toxic epidermal necrolysis;
Special Senses: transient blurred vision, xanthopsia.
Clinical Laboratory Test Findings
In controlled clinical trials, clinically important changes in standard laboratory parameters were rarely associated with administration of Diovan HCT.
Creatinine/Blood Urea Nitrogen (BUN): Minor elevations in creatinine and BUN occurred in 2% and 15% respectively, of patients taking Diovan HCT and 0.4% and 6% respectively, given placebo in controlled clinical trials.
Liver Function Tests: Occasional elevations (greater than 150%) of liver chemistries occurred in Diovan HCT-treated patients.
Neutropenia: Neutropenia was observed in 0.1% of patients treated with Diovan HCT and 0.4% of patients treated with placebo.
The following additional adverse reactions have been reported in valsartan or valsartan/hydrochlorothiazide postmarketing experience. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
Hypersensitivity: There are rare reports of angioedema. Some of these patients previously experienced angioedema with other drugs including ACE inhibitors. Diovan HCT should not be re-administered to patients who have had angioedema.
Digestive: Elevated liver enzymes and very rare reports of hepatitis
Renal: Impaired renal function
Clinical Laboratory Tests: Hyperkalemia
Nervous System: Syncope
Rare cases of rhabdomyolysis have been reported in patients receiving angiotensin II receptor blockers.
The following additional adverse reactions have been reported in post-marketing experience with hydrochlorothiazide:
Acute renal failure, renal disorder, aplastic anemia, erythema multiforme, pyrexia, muscle spasm, asthenia, acute angle-closure glaucoma, bone marrow failure, worsening of diabetes control, hypokalemia, blood lipids increased, hyponatremia, hypomagnesemia, hypercalcemia, hypochloremic alkalosis, impotence, visual impairment.
Pathological changes in the parathyroid gland of patients with hypercalcemia and hypophosphatemia have been observed in a few patients on prolonged thiazide therapy. If hypercalcemia occurs, further diagnostic evaluation is necessary.
Read the Diovan HCT (valsartan and hydrochlorothiazide) Side Effects Center for a complete guide to possible side effects
No clinically significant pharmacokinetic interactions were observed when valsartan was coadministered with amlodipine, atenolol, cimetidine, digoxin, furosemide, glyburide, hydrochlorothiazide, or indomethacin. The valsartan-atenolol combination was more antihypertensive than either component, but it did not lower the heart rate more than atenolol alone.
Coadministration of valsartan and warfarin did not change the pharmacokinetics of valsartan or the time-course of the anticoagulant properties of warfarin.
CYP 450 Interactions: In vitro metabolism studies indicate that CYP 450 mediated drug interactions between valsartan and co-administered drugs are unlikely because of the low extent of metabolism [see CLINICAL PHARMACOLOGY].
Transporters: The results from an in vitro study with human liver tissue indicate that valsartan is a substrate of the hepatic uptake transporter OATP1B1 and the hepatic efflux transporter MRP2. Co-administration of inhibitors of the uptake transporter (rifampin, cyclosporine) or efflux transporter (ritonavir) may increase the systemic exposure to valsartan.
Non-Steroidal Anti-Inflammatory Agents including Selective Cyclooxygenase-2 Inhibitors (COX-2 Inhibitors): In patients who are elderly, volume-depleted (including those on diuretic therapy), or with compromised renal function, coadministration of NSAIDs, including selective COX-2 inhibitors, with angiotensin II receptor antagonists, including valsartan, may result in deterioration of renal function, including possible acute renal failure. These effects are usually reversible. Monitor renal function periodically in patients receiving valsartan and NSAID therapy.
The antihypertensive effect of angiotensin II receptor antagonists, including valsartan may be attenuated by NSAIDs including selective COX-2 inhibitors.
Potassium: Concomitant use of valsartan with other agents that block the renin-angiotensin system, potassium sparing diuretics (e.g. spironolactone, triamterene, amiloride), potassium supplements, or salt substitutes containing potassium may lead to increases in serum potassium and in heart failure patients to increases in serum creatinine. If co-medication is considered necessary, monitoring of serum potassium is advisable.
Dual Blockade of the Renin-Angiotensin System (RAS): Dual blockade of the RAS with angiotensin receptor blockers, ACE inhibitors, or aliskiren is associated with increased risks of hypotension, hyperkalemia, and changes in renal function (including acute renal failure) compared to monotherapy. Closely monitor blood pressure, renal function and electrolytes in patients on Diovan HCT and other agents that affect the RAS.
Do not co-administer aliskiren with Diovan HCT in patients with diabetes. Avoid use of aliskiren with Diovan HCT in patients with renal impairment (GFR < 60 ml/min).
Hydrochlorothiazide: When administered concurrently, the following drugs may interact with thiazide diuretics:
Antidiabetic Drugs (oral agents and insulin) - Dosage adjustment of the antidiabetic drug may be required.
Lithium - Diuretic agents increase the risk of lithium toxicity. Refer to the package insert for lithium preparations before use of such preparations with Diovan HCT. Monitoring of serum lithium concentrations is recommended during concurrent use.
Nonsteroidal Anti-inflammatory Drugs (NSAIDS and COX-2 selective inhibitors) - When Diovan HCT and nonsteroidal anti-inflammatory agents are used concomitantly, the patient should be observed closely to determine if the desired effect of the diuretic is obtained.
Carbamazepine – May lead to symptomatic hyponatremia.
Ion exchange resins: Staggering the dosage of hydrochlorothiazide and ion exchange resins (e.g., cholestyramine, colestipol) such that hydrochlorothiazide is administered at least 4 hours before or 4-6 hours after the administration of resins would potentially minimize the interaction. [see CLINICAL PHARMACOLOGY]
Cyclosporine: Concomitant treatment with cyclosporine may increase the risk of hyperuricemia and gout-type complications.
Read the Diovan HCT Drug Interactions Center for a complete guide to possible interactions
Last reviewed on RxList: 10/16/2012
This monograph has been modified to include the generic and brand name in many instances.
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