Avistar

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Avistar

Medically reviewed

Marina Burgos

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Avistar

Understanding Avistar

Avistar is a medication categorized as an antihistamine, specifically used to manage symptoms associated with various allergic conditions. It belongs to a group of medicines known as second-generation H1-receptor antagonists. These medications work by blocking the effects of histamine, a natural substance in the body that is released during an allergic reaction.

Mechanism of Action

In the body, histamine attaches to specific receptors called H1 receptors. When these receptors are activated, they trigger common allergy symptoms such as itching, swelling, and mucus production. Avistar functions by selectively binding to these H1 receptors without activating them, effectively preventing histamine from triggering the allergic response.

Because it is a second-generation antihistamine, the molecule is designed to have limited penetration into the central nervous system. This characteristic is intended to reduce the likelihood of the drowsiness or sedation often associated with older, first-generation antihistamines.

Primary Indications

Avistar is typically utilized for the management of symptoms related to both seasonal and perennial allergic rhinitis. These symptoms may include:

  • Sneezing
  • Nasal congestion or runny nose
  • Itching of the nose or throat
  • Red, itchy, or watery eyes

Additionally, the medication is used in the treatment of chronic idiopathic urticaria, a condition characterized by the regular appearance of itchy hives or wheals on the skin without an easily identifiable external cause. In these cases, the medication helps to reduce the number and severity of hives and alleviates associated skin irritation.

Regulatory References

  1. Amlodipine - eEML
  2. List of Essential Medicines

What side effects are possible with Avistar?

Possible Side Effects and Safety Information

The safety profile of Avistar (Amlodipine) is structured according to frequency classifications established by regulatory authorities. The most frequently reported adverse reaction is peripheral oedema (swelling, typically of the ankles or feet), which is classified as very common. Official documentation notes this effect is dose-related and may increase during prolonged use.


Adverse effects classified as common (affecting up to 1 in 10 individuals) often include headache, dizziness, somnolence (drowsiness), fatigue, nausea, abdominal pain, flushing, and palpitations. Many of the neurological effects, such as somnolence and dizziness, are typically reported at the initiation of treatment and may become less prominent with continued therapy. Uncommon reactions (affecting up to 1 in 100) span multiple system-organ classes and include tremor, hypotension, and various skin rashes.


Serious adverse reactions are documented in the very rare category (affecting fewer than 1 in 10,000). These include severe events affecting the cardiac system, such as arrhythmia and myocardial infarction, as well as severe hepatobiliary disorders like hepatitis and jaundice. Severe dermatological reactions, including Stevens-Johnson syndrome, are also officially listed as very rare.


Specific safety considerations exist for certain patient populations. Clearance is reduced in older adults and in patients with hepatic impairment, resulting in increased systemic exposure; dose management is officially advised to be cautious in these groups. The medicine is contraindicated in patients with known hypersensitivity to the dihydropyridine class, or in the presence of severe hypotension or cardiogenic shock.

Overdose and Emergency Response

Overdose and When to Seek Help

The official regulatory documents state that an overdose of Avistar (Amlodipine) primarily results in an exaggeration of its intended effects, leading to profound hemodynamic instability. The most significant manifestation is marked and prolonged systemic hypotension (severely low blood pressure), stemming from excessive peripheral vasodilation.

Clinical signs of overdosage may include severe dizziness, drowsiness, and syncope (fainting), alongside disturbances in heart rhythm such as both bradycardia (slow heart rate) and tachycardia (rapid heart rate). Severe toxicity may escalate to life-threatening conditions, including shock, metabolic acidosis, and potentially fatal outcomes.

Immediate emergency medical attention must be sought if an overdose is suspected. Regulators mandate contacting the local emergency services or a national Poison Help hotline, particularly if the individual has collapsed, is having trouble breathing, or cannot be awakened.

Management is strictly symptomatic and supportive, as no specific antidote is known to exist for Amlodipine overdosage. Procedures described for management include gastric lavage or administration of activated charcoal for recent ingestions, along with the use of intravenous fluids and a vasoconstrictor to counter severe hypotension. Due to the long half-life of Amlodipine, prolonged hospital monitoring of cardiac and respiratory function is required, even after initial stabilization.

Therapeutic Uses of Avistar

Main Uses and Therapeutic Goals

Avistar is a pharmacological treatment primarily utilized for the management of specific endocrine and metabolic conditions. Its main application is focused on regulating hormonal imbalances or deficiencies that can impact physical development and metabolic health.

Targeted Conditions

  • Hormone Deficiency: Avistar is frequently used to address insufficient production of endogenous growth hormones. By providing a synthetic equivalent, the medication helps maintain physiological levels necessary for normal cellular function.
  • Growth Regulation in Pediatrics: In children, the treatment is indicated for those who have not met expected growth milestones due to medical conditions that impair natural development.
  • Metabolic Support in Adults: Beyond physical growth, the medication plays a role in managing body composition. It helps in the regulation of lipid profiles, muscle mass maintenance, and bone density in adults who lack sufficient hormone levels.

Potential Benefits and Clinical Outcomes

The primary benefit of Avistar is its ability to mimic natural hormonal signaling to restore systemic balance. The outcomes of therapy are generally categorized into physical development and metabolic stability.

Physical Development

In pediatric patients, the goal of treatment is the achievement of a more standard height velocity. This involves the stimulation of skeletal growth plates, allowing for a gradual increase in linear height over the course of the therapy.

Metabolic and Body Composition Improvements

For adult patients, the benefits often extend to the optimization of metabolic processes:

  • Enhancement of Lean Body Mass: The treatment aids in the development and maintenance of muscle tissue.
  • Reduction of Adipose Tissue: Therapy may assist in the redistribution of body fat, particularly reducing visceral fat accumulation.
  • Bone Mineral Density: Consistent use can contribute to the strengthening of the skeletal structure, reducing the risks associated with low bone mass.
  • Energy Metabolism: By normalizing hormone levels, patients may experience improvements in overall energy regulation and physical stamina.

Eligibility and Restrictions for Use

Who Can and Cannot Use Avistar?

The use of Avistar (Amlodipine) is strictly determined by documented patient population characteristics and is defined by formal regulatory classifications.

Absolute Prohibitions (Contraindications)

Avistar is contraindicated for use in patients with known hypersensitivity to Amlodipine or any other dihydropyridine derivatives. It must also not be used in patients experiencing acute, severe cardiovascular instability, including conditions such as cardiogenic shock, severe hypotension, high-grade aortic stenosis (obstruction of the left ventricular outflow tract), or haemodynamically unstable heart failure following an acute heart attack.

Age and Organ Function Eligibility

  • Adults are eligible for standard use. Older adults and those with severe hepatic impairment are eligible but require the medicine to be initiated at a lower dose and slowly adjusted.
  • Pediatric Use: Use is established for treating high blood pressure in children aged 6 years and older. Safety and efficacy have not been established in children younger than 6 years of age.
  • Renal Impairment: No dose adjustment is required for patients with kidney function impairment, as the drug's processing is not significantly affected by this condition.

Reproductive Status Restrictions

The safety of Avistar in human pregnancy has not been established. Use is only recommended when no safer alternative is available and the mother’s medical condition presents a greater risk. For lactation, the medication is known to be excreted in human milk, necessitating a decision to discontinue either breastfeeding or therapy.

What should I know about interactions with other medicines?

Avistar Interactions with other medicines and products

Avistar, which contains the active substance dutasteride, may interact with certain other medicines primarily due to the way it is metabolized in the body. Dutasteride is broken down by specific liver enzymes known as Cytochrome P450 (CYP)3A4 and CYP3A5.

  • Potent CYP3A4 Inhibitors: Using Avistar concurrently with medicinal products identified as potent, chronic inhibitors of the CYP3A4 enzyme may increase the blood concentrations of Avistar. This is because these inhibitors slow down the rate at which Avistar is cleared from the body. Patients should use caution when taking Avistar with such medicines. Examples of potent CYP3A4 inhibitors include ritonavir and ketoconazole, among others. Your healthcare provider should be aware of all medicines you are taking to manage this potential interaction.

  • Combination Therapy: Avistar is officially indicated for use in combination with the alpha-adrenergic antagonist tamsulosin for the treatment of symptomatic Benign Prostatic Hyperplasia (BPH) in men with an enlarged prostate. Clinical data indicate that tamsulosin does not significantly affect the pharmacokinetics of Avistar.

  • Other Potential Interactions: The concurrent use of grapefruit or grapefruit juice may also increase the blood levels of Avistar, similar to drug-drug interactions involving the CYP3A4 pathway. Patients should consult their healthcare professional regarding dietary constraints.

Mechanism of Action

Blocking Calcium Channels in Arteries

Avistar’s active component works by selectively blocking L-type voltage-dependent calcium channels ( CaV 1.2), which control the entry of Ca^2+ ions into the smooth muscle cells lining the arteries. This inhibition limits the availability of calcium, the crucial ion that triggers muscle contraction, thereby promoting vascular smooth muscle relaxation.

Modulating Systemic Vascular Resistance

The molecular blockade initiates a cascade resulting in widespread vasodilation (artery widening) that reduces Peripheral Vascular Resistance (PVR). This physiological change reduces the total pressure (afterload) against which the heart must pump blood, resulting in a reduction of the heart's mechanical workload and associated oxygen consumption.

Kinetic Determinants of Sustained Action

The mechanism is characterized by a unique, slow rate of association and dissociation from the calcium channel receptor binding site. This kinetic property is responsible for the sustained, long-lasting nature of the calcium channel inhibition, which determines the duration of the resulting physiological effects on the circulation.

Dosage and Administration Information

How to Use Avistar

Avistar (amlodipine) is administered via the oral route, defining its usage as a continuous, once-daily medication. The medication should be taken at the same time each day to maintain consistent levels in the body, and its absorption is unaffected by food, meaning it can be taken with or without meals.

Treatment is initiated at a low dose to assess individual response and generally follows a long-term maintenance schedule, rather than short cycles. Dosage adjustments, or titration, are typically performed after a period of 7 to 14 days to allow sufficient time for the new dose to achieve a steady state.

Official Dosing and Administration Parameters

Parameter Standard Adult Regimen Population Adjustments
Initial Dose 5 mg once daily 2.5 mg once daily for older adults and patients with hepatic impairment
Maximum Dose 10 mg once daily 5 mg once daily maximum for pediatric patients (ages 6–17)
Missed Dose Rule If a dose is missed, do not take a double dose; take the next dose at the regular scheduled time.

Liquid forms (1 mg/mL) are available for the oral route and may also be administered via NG or PEG tubes. Usage typically involves the avoidance of grapefruit or grapefruit juice while on this medication.

Recent Clinical Evidence

Avistar: Recent Clinical Evidence

This section describes the research that has evaluated Avistar (amlodipine), detailing the types of studies that exist for its primary uses, the findings observed in the research populations, and the areas where information is still limited or emerging. Research for its core indications in adults is based on a high volume of controlled, long-term data.


Evidence for Use in Managing High Blood Pressure (Essential Hypertension)

The evidence landscape for Avistar in hypertension was evaluated through numerous large-scale clinical trials, including placebo-controlled and active-comparator RCTs. Researchers examined outcomes related to systemic or functional imbalance, such as changes in systolic and diastolic blood pressure over time. Long-term studies, such as the ALLHAT trial, monitored whether treatment regimens including amlodipine showed patterns related to the rate of major cardiovascular events over several years.

Research described the measured blood pressure readings in the studied adult and pediatric populations. Findings from long-term outcome trials comparing amlodipine against other anti-hypertensive classes reported no significant differences in the incidence of fatal coronary artery disease and myocardial infarction. This evidence contributes to the broader evidence landscape regarding its placement in cardiovascular research.


Evidence for Use in Managing Recurring Chest Discomfort (Angina Pectoris)

The evidence landscape for Avistar in angina, a condition characterized by fluctuating or episodic manifestations of chest discomfort, was evaluated through short-term and intermediate-term RCTs. These studies explored patient-reported outcomes describing perceived discomfort, specifically monitoring the frequency of anginal episodes and the use of rescue medication.

Research highlights changes measured during the study period, including patterns observed in the studies related to the frequency of angina episodes and the duration patients could maintain activity during monitored exercise tests. Studies observed that the measured patterns of symptom frequency were observed throughout the duration of the follow-up period in the clinical trials.


Areas of Remaining Research Uncertainty

Scientific research transparently acknowledges gaps and limitations. Data are still emerging for the use of Avistar in pregnant women, as research has been limited in this area. Furthermore, in certain patients with severe chronic heart failure that is not due to coronary artery disease, studies have reported mixed findings, meaning data are still emerging regarding the durability of findings in this specific population.

Key Studies & References

  1. Amlodipine - StatPearls (Pharmacokinetics and Hepatic Impairment)

Frequently Asked Questions (FAQ)

Common questions about Avistar (FAQ)

Q: What Avistar treats: main uses and benefits

A: Avistar is officially used to help manage high blood pressure (hypertension) and certain types of chest discomfort (angina). The medicine is generally prescribed to manage and help control these conditions over time.


Q: Are there any common side effects that usually go away after a few weeks?

A: Official safety information indicates that some common effects felt at the beginning of treatment may become less noticeable with continued therapy for some users, according to official information. These often include neurological effects such as dizziness and somnolence (a feeling of drowsiness).


Q: Is it normal to feel a bit tired when starting Avistar?

A: Official documents describe both fatigue and somnolence (drowsiness) as common adverse effects reported by users, particularly at the start of therapy. This information is drawn from official product labels.


Q: Is weight gain a possible side effect of Avistar?

A: The most frequently reported physical side effect is peripheral oedema, which is swelling, typically of the ankles or feet. This fluid retention is known to be dose-related. The regulatory label explicitly lists peripheral oedema but does not list 'weight gain' as a separate adverse reaction.


Q: Can Avistar cause issues with sleep or insomnia?

A: Official reports indicate that insomnia (difficulty sleeping) has been reported as an adverse reaction in clinical trials, although at a low incidence. Conversely, somnolence (drowsiness) is listed as a common effect.


Q: Are headaches a frequent side effect reported with Avistar?

A: Yes, headache is officially categorized as a common side effect in regulatory documents. This means it has been reported to affect up to 1 in 10 individuals using the medication.


Q: Can Avistar be taken at the same time as my blood pressure medication?

A: Avistar is officially indicated to be used alone or in combination with certain agents that treat high blood pressure. Official documentation indicates that complex interactions are possible, meaning concurrent use with any other medicines should be managed carefully.


Q: What is the general expectation for improvement when using Avistar?

A: Research data indicates patterns related to a reduction in elevated systolic and diastolic blood pressure readings in studied populations. For chest discomfort (angina), studies focus on measured patterns related to a decrease in the frequency of episodes.


Q: What kind of monitoring or blood tests are required while taking Avistar?

A: Official documents indicate that the label requires lower starting doses and cautious dose management for patients with existing hepatic impairment (liver conditions). Rare postmarketing reports of elevated liver enzymes suggest that monitoring may be considered in specific patient populations.


Q: Is Avistar a new type of drug, or has it been around for a while?

A: The active ingredient in Avistar, Amlodipine, is considered a foundational treatment for cardiovascular conditions. It is included on the World Health Organization's official List of Essential Medicines, recognizing its established role and long history of use in medical practice.


Q: How is Avistar different from other common medications for this condition?

A: Avistar belongs to the drug group known as dihydropyridine Calcium Channel Blockers. This classification defines its fundamental function, which is to selectively promote the relaxation and widening of arteries.


Q: Is there a specific list of foods or drinks that should be avoided while on Avistar?

A: The official product information specifically advises against the consumption of grapefruit or grapefruit juice. This is because these products may affect the way the medicine is processed in the body, potentially leading to increased blood levels.


Q: What did the clinical trials for Avistar focus on?

A: Clinical trials primarily focused on two key measurable outcomes: changes in patients' blood pressure readings and patterns related to the frequency of chest discomfort episodes (angina) throughout the study periods.


Q: Why do some people stop taking Avistar?

A: The most common reported adverse effect that can lead to discontinuation is peripheral oedema (swelling), which is known to be dose-related. Additionally, regulatory documents indicate that discontinuation of the medication can result in the return or worsening of the original condition's symptoms, such as chest pain.


Q: Does Avistar cause long-term side effects that I should be aware of?

A: Official regulatory data includes information on safety collected over many years. This includes very rare, but serious, effects observed in postmarketing experience, such as events affecting the cardiac and hepatic systems.


Q: Can Avistar cause dizziness or affect my ability to drive?

A: Avistar may have a minor to moderate effect on the ability to drive or operate machinery. If side effects like dizziness, headache, fatigue, or nausea occur, the ability to react may be impaired, which is why official information advises caution in these situations.


Q: Is there a risk of dependence or withdrawal symptoms with Avistar?

A: Official regulatory reviews indicate that this medicine is not known to cause drug dependence. However, official information notes that stopping the medication may be associated with the return or worsening of the original condition's symptoms.


Q: What happens if I take Avistar for a long time?

A: Avistar is typically prescribed as a long-term maintenance treatment. Its long-term use has been evaluated in large-scale clinical trials that tracked cardiovascular outcomes over several years.


Q: Does Avistar interact with birth control pills?

A: While the core safety information does not list all oral contraceptives, official documents note the potential for interactions with strong CYP3A4 inhibitors. Since certain components in other medicines are processed by this pathway, official guidance emphasizes that all drug combinations should be carefully managed.


Q: How is Avistar eliminated from the body?

A: The majority of the medicine, about 90%, is extensively processed and broken down (metabolized) by the liver into inactive substances. Only about 10% of the active compound is eliminated from the body through the urine.


Q: Does Avistar affect liver function?

A: Avistar is extensively metabolized by the liver, and official documents describe that the body's clearance of the drug is reduced in patients with existing hepatic impairment. Postmarketing reports have rarely included severe adverse effects such as elevated hepatic enzymes, hepatitis, and jaundice.


Q: Is it true that Avistar can cause changes in vision?

A: Official product information lists visual disturbance, which includes reports of blurred vision, as an uncommon adverse effect. This means it may affect up to 1 in 100 people.


Q: Are there any rare, but serious, allergic reactions associated with Avistar?

A: Yes, official safety information lists hypersensitivity reactions as a contraindication (a reason not to use the drug). Very rare severe skin reactions, including Stevens-Johnson syndrome, have also been reported in the adverse reaction list.


Q: Why is Avistar sometimes used along with other medicines?

A: Official indications state that Avistar may be used alone or in combination with other agents that treat high blood pressure or chest pain. This is done to achieve better overall management of complex cardiovascular conditions.


Q: Is there a specific time of day Avistar is generally recommended to be taken?

A: Avistar is a once-daily medicine and official guidance states it should be taken at the same time each day to maintain consistent levels in the body. However, no specific time of day (morning or night) is mandated for the general population.

How should Avistar be stored and disposed of?

Official Storage and Disposal Profile (Based on Regulatory Documents for Bevacizumab)

This medicine must be stored strictly according to official regulatory specifications to maintain its stability and effectiveness.

Storage Requirements

Condition Requirement (Official Statement)
Temperature Store in a refrigerator at 2 C to 8 C (36 F to 46 F).
Protection Keep the vial in its original carton to protect it from light and do not freeze or shake the product.
Handling Must be diluted only with 0.9% Sodium Chloride Injection, USP (saline) and must not be mixed with dextrose solutions.

Stability and Disposal

This product is a single-dose vial and contains no preservatives. Once the product is diluted, it has a limited in-use stability period (typically 8 to 24 hours depending on documentation). Any portion of the medicine remaining in the vial or infusion bag after use must be discarded according to established institutional waste protocols. The product is not intended for multi-dose use.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

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