If you’ve been diagnosed with depression or schizophrenia, your doctor may discuss Rexulti with you.

It’s a prescription drug that’s used in adults to treat:

For MDD, Rexulti is used together with an antidepressant. But for schizophrenia, Rexulti may be used alone or together with other drugs.

To learn more about MDD and schizophrenia and how Rexulti is used for them, see the “Is Rexulti used for depression?” and “Is Rexulti used for other conditions?” sections below.

Rexulti basics

Rexulti contains the active drug brexpiprazole. It’s not currently available as a generic medication. Brexpiprazole only comes as the brand-name drug Rexulti.

Rexulti isn’t considered an antidepressant drug. Rather, it’s classified as an atypical antipsychotic. This is a newer group of drugs that’s used for various mental health conditions such as:

Rexulti comes as tablets that you’ll take by mouth.

Read on to learn about Rexulti’s side effects, how it’s taken, and more.

Like most drugs, Rexulti may cause mild or serious side effects. The lists below describe some of the more common side effects. These lists don’t include all possible side effects. Your doctor or pharmacist can provide complete side effect information about Rexulti.

Keep in mind that side effects of a drug can depend on:

  • your age
  • other health conditions you have
  • other medications you may be taking

Your doctor or pharmacist can tell you more about the potential side effects of Rexulti. They can also suggest ways to help reduce side effects.

Mild side effects

Here’s a short list of some of the mild side effects that Rexulti can cause. To learn about other mild side effects, talk with your doctor or pharmacist, or read Rexulti’s medication guide.

Mild side effects of Rexulti that have been reported include:

Mild side effects of many drugs may go away within a few days or a couple of weeks. But if they become bothersome, talk with your doctor or pharmacist.

Serious side effects

Serious side effects from Rexulti can occur, but they aren’t common. If you have serious side effects from Rexulti, call your doctor right away. However, if you think you’re having a medical emergency, you should call 911 or your local emergency number.

Serious side effects of Rexulti that have been reported include:

Note: If you have symptoms of a serious side effect such as NMS, you should call 911 or your local emergency number.

* For more information on this side effect, see the “Side effect focus” section below.

Side effect focus

Learn more about some of the side effects Rexulti may cause.

Boxed warnings

Rexulti has boxed warnings. These are serious warnings about a medication from the Food and Drug Administration (FDA). Rexulti’s boxed warnings are described below.

Risk of death in older adults with psychosis related to dementia. Rexulti should not be used in older adults to treat psychosis that’s related to dementia.

With psychosis, you may experience impaired mental well-being. Symptoms can include:

With dementia, you have changes in your mental status. These changes can include:

  • memory loss
  • alterations in your language, thinking, speech, or behavior

Using Rexulti for psychosis that’s related to dementia may increase the risk of death in this group of people.

Risk of suicidal thoughts or behaviors. Using antidepressant medications in people ages 24 years and younger can increase suicidal thoughts and behaviors. Rexulti isn’t considered an antidepressant. But it’s used to treat depression together with an antidepressant.

Rexulti is not recommended for use in people younger than 18 years of age.

If you’ve ever had thoughts of self-harm, talk with your doctor before taking Rexulti. They can discuss the risks of Rexulti use with you.

What might help

It’s not clear why Rexulti may increase the risk of death in older adults with dementia related to psychosis. Keep in mind that other things can affect this risk. This includes having other health conditions or taking other medications. If you’re concerned about this risk, ask your doctor about the safety of taking Rexulti.

Rexulti can also increase the risk for suicidal thoughts or behavior. This risk is higher in people who have had a mental health condition. This could include depression or bipolar disorder.

Be sure to share your medical history with your doctor before taking Rexulti. Tell them your health history, including if you’ve had any suicidal thoughts or behaviors in the past.

Suicide prevention

If you think someone is at immediate risk of self-harm or hurting another person:

  • Call 911 or your local emergency number.
  • Stay with the person until help arrives.
  • Remove any guns, knives, medications, or other things that may cause harm.
  • Listen, but don’t judge, argue, threaten, or yell.

If you or someone you know is considering suicide, get help from a crisis or suicide prevention hotline. Try the National Suicide Prevention Lifeline at 800-273-8255.

Weight gain

It’s possible to have weight gain while you’re taking Rexulti. But how much weight you may gain with Rexulti can vary based on:

  • your metabolism (the chemical processes happening inside your body)
  • your diet
  • how long you’re taking Rexulti

Studies have shown that weight gain is a common side effect of brexpiprazole, which is the active drug in Rexulti.

What might help

Talk with your doctor about weight changes that can happen with Rexulti and what you can expect with treatment.

If you’re concerned about weight gain, ask your doctor about lifestyle changes to help you maintain a healthy weight with Rexulti. If you are bothered by weight gain with the drug, do not suddenly stop taking Rexulti. Doing so may worsen symptoms you were using the drug to treat.

Anger or other changes in your mood

Taking Rexulti can cause changes in your mood, thoughts, or behaviors. Examples of possible changes include:

These side effects are rare with Rexulti.

What might help

Before starting Rexulti, ask your doctor about mood-related side effects that the drug may cause. Discuss with your doctor the benefits and risks of using this medication.

If you have changes or worsening of your mood or behavior while taking Rexulti, call your doctor. But if you’re having serious changes in your mental health or you’re having thoughts of harming yourself, call 911 or your local emergency number right away.

Allergic reaction

Some people may have an allergic reaction to Rexulti. While allergic reaction wasn’t reported in studies of Rexulti, it can still happen.

Symptoms of a mild allergic reaction can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include swelling under your skin, typically in your eyelids, lips, hands, or feet. They can also include swelling of your tongue, mouth, or throat, which can cause you to have trouble breathing.

Call your doctor right away if you have an allergic reaction to Rexulti. But if you think you’re having a medical emergency, call 911 or your local emergency number.

Your doctor will explain how you should take Rexulti. They will also explain how much to take and how often. Be sure to follow your doctor’s instructions. Below are commonly used dosages, but always take the dosage your doctor prescribes.

Taking Rexulti

Rexulti contains the active drug brexpiprazole and comes as tablets you’ll swallow.

It’s available in these strengths:

  • 0.25 milligram (mg)
  • 0.5 mg
  • 1 mg
  • 2 mg
  • 3 mg
  • 4 mg

Dosage

Your dosage of Rexulti will depend on:

  • the condition you’re taking Rexulti to treat
  • how well your body responds to the drug
  • other medications you may be taking
  • any side effects that you may have from Rexulti
  • other health conditions you have, such as liver or kidney problems, or how well your body breaks down certain medications

For depression, you’ll take Rexulti once each day, along with another depression medication.

Your doctor will start you on a low dose of Rexulti, and they’ll monitor your body’s response to treatment. After your first few weeks of treatment, your doctor will likely increase your Rexulti dosage.

The maximum dosage of Rexulti for depression is 3 mg once daily.

For schizophrenia, you’ll take a low dose of Rexulti once daily on days 1 to 4 of treatment. Then your doctor will increase your daily dose on days 5 to 7. If needed, they may increase your daily dose more, starting on day 8.

The maximum dosage for schizophrenia is 4 mg once daily.

To learn more about depression and schizophrenia and how Rexulti is used for them, see the “Is Rexulti used for depression?” and “Is Rexulti used for other conditions?” sections below.

Taking Rexulti with other drugs

For depression, Rexulti is taken together with an antidepressant.

Some examples of antidepressant drugs that may be used with Rexulti include:

For schizophrenia, Rexulti may be used on its own.

Talk with your doctor to learn about your treatment plan and recommended medications.

Questions about taking Rexulti

Here’s a list of common questions related to taking Rexulti.

  • What if I miss a dose of Rexulti? If you miss a dose of Rexulti, take it as soon as you remember. But do not double up on your next dose. Doing so can increase the side effects of Rexulti. If it’s close to when you’d take your next dose, just skip the missed dose. Then take your usual dose at your regular time. You can also try using a reminder tool to stay on track with your doses.
  • Will I need to use Rexulti long term? There’s no specific timeline for using Rexulti. You and your doctor will discuss your treatment plan. If Rexulti is working to reduce your symptoms, you may take it long term.
  • Can Rexulti be chewed, crushed, or split? No, you should take Rexulti tablets whole. Crushing, chewing, or splitting the tablets may change how they work in your body. If you have trouble swallowing pills, try these tips, or talk with your pharmacist about suggestions for taking Rexulti.
  • Should I take Rexulti with food? You can take Rexulti with or without food. Eating around the time of your doses doesn’t change how the drug works in your body.
  • How long does Rexulti take to work? It may take a few days to several weeks for Rexulti to start reducing your symptoms. How quickly the drug works depends on individual factors, such as your condition and how your body responds to Rexulti. Ask your doctor what you can expect with treatment.
Questions for your doctor

You may have questions about Rexulti and your treatment plan. It’s important to discuss all your concerns with your doctor.

Here are a few tips that might help guide your discussion:

  • Before your appointment, write down questions like:
    • How will Rexulti affect my body, mood, or lifestyle?
  • Bring someone with you to your appointment if doing so will help you feel more comfortable.
  • If you don’t understand something related to your condition or treatment, ask your doctor to explain it to you.

Remember, your doctor and other healthcare professionals are available to help you. And they want you to get the best care possible. So don’t be afraid to ask questions or offer feedback on your treatment.

Rexulti and Abilify both belong to a group of drugs called atypical antipsychotics. These are newer drugs that have fewer serious side effects than older antipsychotic drugs (called first generation antipsychotics).

Rexulti and Abilify have some similar uses and effects, but they also have some differences. For instance, Rexulti contains the active drug brexpiprazole, while Abilify contains the active drug aripiprazole.

Both Rexulti and Abilify are used to treat depression and schizophrenia. But Abilify is also used to treat other conditions.

Rexulti comes as tablets you’ll swallow. Abilify, on the other hand, comes in several forms. These forms include:

To learn more about these two drugs, see this side-by-side comparison. And be sure to talk with your doctor if you’d like to know about which drug is right for you.

Below are answers to some commonly asked questions about Rexulti.

Will I have withdrawal symptoms if I stop taking Rexulti?

No, you won’t. Rexulti doesn’t cause physical dependence, so stopping it doesn’t lead to withdrawal. (With dependence, your body needs the drug in order for you to feel normal.)

But suddenly stopping the drug could worsen symptoms you were using the drug to treat. So you should not suddenly stop taking Rexulti.

If you’re having side effects or you have other concerns about Rexulti use, talk with your doctor. They can recommend a treatment plan that’s right for you.

Is Rexulti used for anxiety? If so, what’s the dosage for anxiety?

No, Rexulti is not approved for anxiety. The drug may be used off-label for anxiety, but there are other treatments for anxiety that have been approved. (With off-label use, a drug is used to treat conditions other than those it’s been approved for.)

You can also ask your doctor for information about using Rexulti for anxiety, including the typical dosage given.

Also, keep in mind that in rare cases, Rexulti can cause anxiety as a side effect. If you’re having anxiety with Rexulti, talk with your doctor. They can discuss options with you to help manage your anxiety.

Does Rexulti treat bipolar disorder?

No, Rexulti is not approved for bipolar disorder. The drug may be used off-label for this condition, but there are other medications that are approved for bipolar disorder and may be better options. (With off-label use, a drug is used to treat conditions other than those it’s been approved to treat.)

Your doctor can tell you more about how Rexulti works. They can also provide information about other treatment options for bipolar disorder.

How does Rexulti compare with the alternative drugs Vraylar and Seroquel?

Rexulti, Vraylar, and Seroquel work in similar ways. They all belong to a group of drugs called atypical antipsychotics. These medications are newer drugs that have fewer serious side effects than older antipsychotic drugs (called first generation antipsychotics).

These three medications each contain a different active ingredient:

  • Rexulti has the active drug brexpiprazole
  • Vraylar has the active drug cariprazine
  • Seroquel has the active drug quetiapine

Rexulti is used to treat depression and schizophrenia. For depression, Rexulti is taken together with an antidepressant. For schizophrenia, Rexulti may be taken alone. Rexulti comes as tablets that you’ll take by mouth.

Vraylar comes as a capsule that you’ll take by mouth. It’s used to treat:

Seroquel comes as tablets that you’ll take by mouth. It’s used to treat depression, bipolar disorder, and schizophrenia.

If you’d like more information about how these medications compare with one another, talk with your doctor. They can discuss all your treatment options and the benefits and risks of each drug.

What’s the half-life of Rexulti? And how long does it stay in your system?

Rexulti’s active drug brexpiprazole has a half-life of 91 hours. This means it takes 91 hours for half of a dose of brexpiprazole to be cleared from your body.

In general, it takes about four to five half-lives for a full dose of a drug to be fully cleared from your body.

How long a drug stays in your system can vary based on personal factors. These include your genetic makeup and how well your liver and kidneys are working. Rexulti can stay in your body for several days.

How does Rexulti work?

Rexulti’s exact mechanism of action isn’t known. (A drug’s mechanism of action describes how it works.)

But this type of medication is thought to work by regulating certain neurotransmitters in your brain. (Neurotransmitters are brain chemicals.)

Specifically, Rexulti is thought to work on dopamine and serotonin. It’s believed this drug works by balancing dopamine and serotonin to help reduce symptoms of depression and schizophrenia.

If you’ve been diagnosed with depression or schizophrenia, your doctor may discuss Rexulti with you. To learn more about its use for depression, read on. For information about Rexulti’s use in treating schizophrenia, see the section directly below.

Rexulti is used in adults with major depressive disorder (MDD), which is also commonly called depression.

Brief periods of sadness are natural for everyone. But with depression, you have ongoing, intense feelings of sadness. These feelings impact your quality of life, sleep, and other aspects of your life.

For MDD, Rexulti is prescribed together with an antidepressant. This is considered combination therapy.

Rexulti belongs to a group of drugs called second generation antipsychotics. These are newer drugs that have fewer serious side effects than older antipsychotic drugs. It’s thought that Rexulti works for depression by helping to balance certain chemicals in your brain.

If you’d like, talk with your doctor for more information about the pros and cons of using Rexulti for MDD.

If you’ve been diagnosed with depression or schizophrenia, your doctor may discuss Rexulti with you. To learn more about its use for depression, see the section directly above. For information about Rexulti’s use in treating schizophrenia, read on.

Rexulti is prescribed for adults with schizophrenia, which is a complex mental health condition. Schizophrenia has varying symptoms, including:

Studies show that people with schizophrenia have imbalances in brain chemicals called neurotransmitters. It’s thought that Rexulti works by regulating levels of two neurotransmitters: dopamine and serotonin.

Your doctor can provide more information to you about the benefits and risks of Rexulti use for schizophrenia.

Costs of prescription drugs can vary depending on many factors. These factors include what your insurance plan covers and which pharmacy you use.

If you have questions about how to pay for your prescription, talk with your doctor or pharmacist. You can also visit the Rexulti manufacturer’s website to see if they have support options.

Talk with your doctor about all your medications and any other health conditions you have before starting treatment with Rexulti.

Tell your doctor if you have kidney or heart problems, diabetes, high cholesterol or high triglycerides. And let them know if you’ve ever had seizures or any other medical problems.

Additionally, tell your doctor if you’re pregnant, planning to become pregnant, or planning to breastfeed while taking Rexulti. Antipsychotics, such as Rexulti, may increase certain risks if used in pregnancy.

These and other considerations are described below.

Interactions

Taking medications, vaccines, foods, and other things with a certain drug can affect how the drug works. These effects are called interactions.

Before taking Rexulti, be sure to tell your doctor about all medications you take, including prescription and over-the-counter types. Also describe any vitamins, herbs, or supplements you use. Your doctor or pharmacist can tell you about any interactions these items may cause with Rexulti.

Interactions with drugs or supplements

Rexulti can interact with several types of drugs. Rexulti is broken down in your liver by certain enzymes (types of proteins). If you take drugs with Rexulti that are also broken down by these enzymes, the drugs may interact and cause side effects.

Some types of drugs can increase the effects of Rexulti. In this case, your doctor may need to lower the dose of Rexulti to lessen your risk for adverse reactions. Examples of these drugs include:

Certain other drugs can reduce the effects of Rexulti by clearing it faster than usual from your body. In this case, your doctor may need to increase your dose of Rexulti. Some examples of these drugs include:

This list does not contain all types of drugs that may interact with Rexulti. Your doctor or pharmacist can tell you more about these interactions and any others that may occur when using Rexulti.

Other interactions

Rexulti may also interact with herbs and supplements.

For example, St. John’s wort may reduce the effects of Rexulti. Do not take this herb with Rexulti. Tell your doctor if you were taking this herb before starting treatment with Rexulti.

Boxed warnings

Rexulti has boxed warnings. These are serious warnings about a medication from the Food and Drug Administration (FDA). Rexulti’s boxed warnings are described below.

Risk of death in older adults with psychosis related to dementia. Rexulti should not be used in older adults (ages 65 years or older) to treat psychosis that’s related to dementia. (With psychosis, you lose touch with reality. And with dementia, you have changes in your mental status.)

This is because Rexulti can increase the risk of death in older adults with this condition.

Risk of suicidal thoughts or behaviors. Using antidepressant medications in people ages 24 years and younger can increase suicidal thoughts and behaviors. Rexulti isn’t considered an antidepressant. But it’s used to treat depression together with an antidepressant.

Rexulti is not recommended for use in people younger than 18 years of age.

For more information about these warnings, see the “What are Rexulti’s side effects?” section above.

Other warnings

Rexulti may not be right for you if you have certain medical conditions or other factors that affect your health. Talk with your doctor about your health history before you take Rexulti. Factors to consider include those in the list below.

  • Liver problems. If you have problems with your liver or serious liver disease, your doctor may adjust your dose of Rexulti. Be sure to tell your doctor about any history of liver-related problems.
  • Allergic reaction. If you’ve had an allergic reaction to Rexulti or any of its ingredients, you should not take Rexulti. Ask your doctor what other medications are better options for you.
  • Poor metabolism of certain drugs, including Rexulti. Certain people’s bodies have trouble metabolizing (breaking down) medications such as Rexulti because of genetic factors. This means the drug may last longer in their body and cause side effects. Your doctor will check to see if your body has poor metabolism of Rexulti. If needed, your doctor may adjust your dose of the drug.
  • Kidney problems. If you have kidney disease, you may need a lower dose of Rexulti. Your doctor will check your kidney function to decide the best dose of Rexulti for you.
  • Diabetes. Taking Rexulti may increase blood sugar levels in certain people. If you have diabetes, you may be at higher risk for this side effect. Rexulti can increase blood sugar to dangerous levels and cause diabetic ketoacidosis and diabetic coma. In rare cases, this can cause death. You may need to monitor your blood sugar level more often than usual when using Rexulti. If you have diabetes, ask your doctor if Rexulti is safe for you to take.
  • Heart or blood pressure problems. Rexulti can cause orthostatic hypotension (a drop in your blood pressure when you stand up or sit up from lying down). This condition can cause dizziness or fainting. If you have heart or blood pressure problems, ask your doctor if it’s safe for you to use Rexulti. Additionally, it’s important to avoid dehydration (low fluid level in your body) while taking the drug. Being dehydrated can increase your risk of low blood pressure.
  • Seizures. Taking Rexulti may increase your risk for seizures. The risk is higher for people with a seizure disorder or with older age. Talk with your doctor about your health history to see if Rexulti is safe for you.
  • Cholesterol problems. Rexulti can increase lipids in people who have high cholesterol or triglycerides. Your doctor may check your lipid levels before you start Rexulti treatment and during treatment with the drug.
  • Low white blood cell count. Rexulti may cause leukopenia (low white blood cell level) or neutropenia (low level of certain white blood cells). If you already have low white cell count, you may be at a higher risk. Symptoms of low white blood cell count can include fever and infection. If needed, your doctor will order blood tests for you before you start taking Rexulti. Check with your doctor to see if you’ll need to have your blood cell levels checked.
  • Trouble regulating your body temperature. Rexulti can make it harder for your body to regulate its temperature. For example, it may be harder for you to cool down after exercising. If you already have a condition that causes trouble with regulating your body temperature, be sure to tell your doctor. They can help determine if Rexulti is a safe option for you.
  • Falls. Taking Rexulti can cause problems with your blood pressure, which could lead to dizziness and falls. If you’re already at risk for falls due to medications you take or conditions you have, you may be at higher risk. Talk with your doctor about your risk for falls before you take Rexulti.

Use with alcohol

Drinking alcohol with Rexulti may increase your risk for certain side effects.

For example, Rexulti can cause sleepiness and certain movement problems. And drinking alcohol may make these side effects worse. Taking Rexulti and drinking alcohol may also affect your liver function.

If you plan to drink alcohol while you’re taking Rexulti, ask your doctor if it’s safe to do so.

Pregnancy and breastfeeding

There’s no specific information about the risks of Rexulti use during pregnancy.

But some data show that similar drugs taken during the third trimester of pregnancy increase the risk for extrapyramidal symptoms in infants exposed to them. (Extrapyramidal symptoms are a certain movement disorder.)

Using Rexulti during the third trimester of pregnancy may also increase the risk for withdrawal symptoms in infants exposed to the drug. Examples of withdrawal symptoms can include:

  • tremors
  • trouble breathing
  • agitation
  • sleepiness
  • trouble feeding

Your doctor can discuss the risks and benefits of taking Rexulti during pregnancy. If you become pregnant while taking Rexulti, tell your doctor right away.

If you do use Rexulti during pregnancy, consider signing up for the pregnancy registry available for medications called atypical antipsychotics. (Keep in mind that Rexulti is an atypical antipsychotic.) You can either call 866-961-2388 or visit the registry website to learn more.

It’s not known if Rexulti is safe to use while breastfeeding. The drug may pass into breast milk and cause side effects for a breastfed child.

Ask your doctor about the risks of using Rexulti if you plan to breastfeed. They can recommend if you should stop breastfeeding while taking this drug.

Rexulti and Latuda have some similarities and differences. They belong to the same group of drugs called atypical antipsychotics. These medications are newer drugs that have fewer serious side effects than older antipsychotic drugs (called first generation antipsychotics).

Rexulti and Latuda have different active ingredients. Rexulti contains the active drug brexpiprazole, while Latuda contains the active drug lurasidone hydrochloride.

These medications are both used to treat schizophrenia in adults. But Latuda can also be used in children and teens ages 10 to 17 years with schizophrenia.

Rexulti is also used to treat depression. And Latuda is also used to treat bipolar disorder.

See this detailed comparison of Rexulti and Latuda for more information. And check with your doctor about which drug they recommend for your condition.

Do not take more Rexulti than your doctor prescribes. Using more than this can lead to serious side effects. To see a list of Rexulti’s possible side effects, see the “What are Rexulti’s side effects?” section above.

What to do in case you take too much Rexulti

Call your doctor if you think you’ve taken too much Rexulti. You can also call 800-222-1222 to reach the American Association of Poison Control Centers, or use their online resource. However, if you have severe symptoms, immediately call 911 (or your local emergency number) or go to the nearest emergency room.

Several treatment options are available for depression and schizophrenia. Rexulti is one option your doctor may discuss with you. For more information about these conditions, see the “Is Rexulti used for depression?” and “Is Rexulti used for other conditions?” sections above.

Ask your doctor about the pros and cons of treatment with Rexulti, and what you can expect while taking it. Here are a few questions to help you get started:

And consider reading these articles to learn more information:

You can also sign up for Healthline’s online newsletter for the advice on managing depression.

Q:

Will I need to stop taking Rexulti if I’m taking an antibiotic for an infection?

Anonymous patient

A:

Maybe. It depends on the antibiotic your doctor prescribes to treat your infection. But most antibiotics are OK to take with Rexulti.

Some types of drugs can increase the effects of Rexulti. This includes certain antibiotics.

If you’re prescribed an antibiotic that increases your risks for side effects from Rexulti, your doctor may have you temporarily stop taking Rexulti until your infection clears.

Examples of antibiotics that can interact with Rexulti include:

Keep in mind that if you’re prescribed a medication that you’ll apply topically, such as erythromycin eye ointment, it likely won’t interact with Rexulti.

If your doctor or dentist prescribes an antibiotic to treat an infection, make sure they’re aware that you’re taking Rexulti. They can check for any drug interactions and recommend a treatment that’s safe for you.

Alex Brewer, PharmD, MBAAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.