Venlafaxine
Venlafaxine
Definition
Venlafaxine is an antidepressant available in the United States under the trade name of Effexor or Effexor XR.
Purpose
Venlafaxine is used to treat depression and generalized anxiety disorder . It has also been used to treat obsessive-compulsive disorder and irritable bowel syndrome.
Description
Venlafaxine is an antidepressant. It has actions common to both the cyclic antidepressants such as imipramine (Tofranil) and amitriptyline (Elavil), and the selective serotonin reuptake inhibitors (SSRIs ) such as fluoxetine (Prozac), sertraline (Zoloft), and paroxetine (Paxil ). It is believed to derive its actions by increasing levels of both norepinephrine and serotonin in the brain .
The therapeutic effects of venlafaxine, like other antidepressants, appear slowly. Maximum benefit is often not evident for at least two weeks after starting the drug. People taking venlafaxine should be aware of this and continue taking the drug as directed even if they do not see immediate improvement.
Venlafaxine is broken down by the liver and eliminated from the body by the kidneys. As a result, the dose of venlafaxine must be lowered in people with liver or kidney disease.
Venlafaxine is available in 25-mg, 37.5-mg, 50-mg, 75-mg, and 100-mg rapid-release tablets and 75-mg and 150-mg extended-action capsules.
Recommended dosage
The recommended initial dose of venlafaxine is 75 mg daily taken as two or three equal doses. The dose may be increased in 75-mg increments every four days as needed until symptoms of depression or anxiety resolve. Most commonly, dosages range between 150 mg to 225 mg daily, although in severe situations 375 mg per day may be needed. Once patients are stabilized using the rapid-acting tablets, they may be converted over to the appropriate dose of extended-release capsules.
In people with liver disease, the daily dosage of venlafaxine should be cut in half. In patients with kidney disease, the daily dosage of venlafaxine should be reduced 25–50%, depending upon the extent of kidney damage. When stopping venlafaxine, the dosage should be reduced gradually over a period of at least two weeks before the drug is totally stopped.
Precautions
Patients taking venlafaxine should be monitored closely for insomnia , anxiety, mania, significant weight loss, seizures , and thoughts of suicide .
Caution should also be exercised when prescribing venlafaxine to patients with impaired liver or kidney function, the elderly (over age 60), children, individuals with known manic-depressive disorder or a history of seizures, people with diabetes, and individuals expressing ideas of committing suicide.
Individuals should not take monoamine oxidase (MAO) inhibitors such as Nardil during venlafaxine therapy, for two weeks prior to beginning venlafaxine therapy, and for five weeks after stopping venlafaxine therapy.
Care should be taken to weigh the risks and benefits of this drug in women who are, or wish to become, pregnant, as well as in breast-feeding mothers.
People with diabetes should monitor their blood or urine sugar more carefully, since venlafaxine may affect blood sugar.
Until individuals understand the effects that venlafaxine may have, they should avoid driving, operating dangerous machinery, or participating in hazardous activities. Alcohol should not be used while taking venlafaxine.
Side effects
More common side effects include decreased sexual drive, restlessness, difficulty sitting still, skin rash, hives, and itching.
Less common side effects include fever and/or chills, and pain in joints or muscles.
Rare side effects include pain or enlargement of breasts and/or abnormal milk production in women, seizures, fast heart rate, irregular heartbeats, red or purple spots on the skin, low blood sugar and its symptoms (anxiety, chills, cold sweats, confusion, difficulty concentrating, drowsiness, excess hunger, rapid heart rate, headache, shakiness or unsteadiness, severe fatigue ), low blood sodium and its symptoms (including confusion, seizures, drowsiness, dry mouth, severe thirst, decreased energy), serotonin syndrome (usually at least three of the following: diarrhea, fever, sweati-ness, mood or behavior changes, overactive reflexes, fast heart rate, restlessness, shivering or shaking), excitability, agitation, irritability, pressured talking, difficulty breathing, and odd body or facial movements.
Interactions
Venlafaxine interacts with a long list of other medications. Anyone starting this drug should review the other medications they are taking with their physician and pharmacist for possible interactions. Patients
KEY TERMS
Antihistamine —A medication used to alleviate allergy or cold symptoms such as runny nose, itching, hives, watering eyes, or sneezing.
Antipsychotic —A medication used to treat psychotic symptoms of schizophrenia such as hallucinations, delusions, and delirium. May be used to treat symptoms in other disorders as well.
Depression —A mental state characterized by excessive sadness. Other symptoms include altered sleep patterns, thoughts of suicide, difficulty concentrating, agitation, lack of energy, and loss of enjoyment in activities that are usually pleasurable.
Generalized anxiety disorder —A general form of fear that can dominate a person’s life.
Mania —An elevated or euphoric mood or irritable state that is characteristic of bipolar I disorder. This state is characterized by mental and physical hyperactivity, disorganization of behavior, and inappropriate elevation of mood.
Neurotransmitter —A chemical in the brain that transmits messages between neurons, or nerve cells.
Obsessive-compulsive disorder —A disorder in which affected individuals have an obsession (such as a fear of contamination, or thoughts they do not like to have and cannot control) and feel compelled to perform certain acts to neutralize the obsession (such as repeated hand washing).
Serotonin syndrome —A condition characterized by at least three of the following symptoms: diarrhea, fever, extreme perspiration, mood or behavior changes, overactive reflexes, fast heart rate, restlessness, shivering, or shaking. It is a result of too much serotonin in the body.
should always inform all their health care providers, including dentists, that they are taking venlafaxine.
Dangerously high blood pressure, rapid changes in heart rate, high fever, muscle stiffness, and sudden muscle spasms have resulted from the combination of antidepressants, such as venlafaxine, and members of another class of antidepressants known as monoamine oxidase (MAO) inhibitors. Because of these serious adverse reactions, venlafaxine should never be taken in combination with MAO inhibitors. Patients taking any MAO inhibitors, for example Nardil (phenelzine sulfate) or Parnate (tranylcypromine sulfate), should stop the MAO inhibitor, and wait at least 14 days before starting venlafaxine or a tricyclic antidepres-sant. The same holds true when discontinuing venlafaxine and starting an MAO inhibitor.
Some other drugs such as trazodone (Desyrel), sibutramine (Meridia), and sumatriptan (Imitrex) also interact with venlafaxine and cause a syndrome known as neuroleptic malignant syndrome, characterized by irritability, muscle stiffness, shivering, muscle spasms, and altered consciousness.
The sedative effects (drowsiness or lack of mental clarity) of venlafaxine are increased by other central nervous system depressants such as alcohol, sedatives , sleeping medications, or other medications used for mental disorders such as schizophrenia .
Resources
BOOKS
Facts and Comparisons staff. Drug Facts and Comparisons. 6th ed. St. Louis, MO: Facts and Comparisons, 2002.
Preston, John D., John H. O’Neal, and Mary C. Talaga. Handbook of Clinical Psychopharmacology for Therapists. 4th ed. Oakland, CA: New Harbinger Publications, 2004.
Wyeth Laboratories staff. Effexor Package Insert. Philadelphia, PA: Wyeth Laboratories, 2001.
PERIODICALS
Baca, Enrique, and others. “Venlafaxine Extended-Release in Patients Older than 80 Years with Depressive Syndrome.” International Journal of Geriatric Psychiatry 21.4 (Apr. 2006): 337–43.
Baldwin, David S. “Serotonin Noradrenaline Reuptake Inhibitors: A New Generation of Treatment for Anxiety Disorders.” International Journal of Psychiatry in Clinical Practice 10, Suppl. 2 (June 2006): 12–15.
Davidson, Jonathan, and others. “Treatment of Posttrau-matic Stress Disorder with Venlafaxine Extended Release.” Archives of General Psychiatry 63.10 (Oct. 2006): 1158–65.
Johnson, Ellyn M., and others. “Cardiovascular Changes Associated With Venlafaxine in the Treatment of Late-Life Depression.” American Journal of Geriatric Psychiatry 14.9 (Sept. 2006): 796–802.
Kim, Tae-Suk, and others. “Comparison of Venlafaxine Extended Release Versus Paroxetine for Treatment of Patients with Generalized Anxiety Disorder.” Psychiatry and Clinical Neurosciences 60.3 (June 2006): 347–51.
McGrath, Patrick J, and others. “Tranylcypromine Versus Venlafaxine Plus Mirtazapine Following Three Failed Antidepressant Medication Trials for Depression: A STAR*D Report.” American Journal of Psychiatry 163.9 (Sept. 2006): 1531–41.
Montgomery, Stuart A. “Escitalopram Versus Venlafaxine XR in the Treatment of Depression.” International Clinical Psychopharmacology 21.5 (Sept. 2006): 297–309.
Nemeroff, Charles B., and Michael E. Thase. “A Double-Blind, Placebo-Controlled Comparison of Venlafaxine
and Fluoxetine Treatment in Depressed Outpatients.” Journal of Psychiatric Research 41.3–4 (Apr.–June 2007): 351–59.
Post, R. M., and others. “Mood Switch in Bipolar Depression: Comparison of Adjunctive Venlafaxine, Bupro-pion and Sertraline.” British Journal of Psychiatry 189.2 (Aug. 2006): 124–31.
Rush, A. John, and others. “Bupropion-SR, Sertraline, or Venlafaxine-XR after Failure of SSRIs for Depression.” New England Journal of Medicine 354.12 (Mar. 2006): 1231–42.
Schatzberg, Alan, and Steven Roose. “A Double-Blind, Placebo-Controlled Study of Venlafaxine and Fluoxetine in Geriatric Outpatients with Major Depression.” American Journal of Geriatric Psychiatry 14.4 (Apr. 2006): 361–70.
Thase, Michael E., Richard C. Shelton, and Arifulla Khan. “Treatment with Venlafaxine Extended Release after SSRI Nonresponse or Intolerance: A Randomized Comparison of Standard- and Higher-Dosing Strategies.” Journal of Clinical Psychopharmacology 26.3 (June 2006): 250–58.
Tiihonen, Jari, and others. “Antidepressants and the Risk of Suicide, Attempted Suicide, and Overall Mortality in a Nationwide Cohort.” Archives of General Psychiatry 63.12 (Dec. 2006): 1358–67.
Yazicioglu, Bengi, and others. “A Comparison of the Efficacy and Tolerability of Reboxetine and Sertraline Versus Venlafaxine in Major Depressive Disorder: A Randomized, Open-Labeled Clinical Trial.” Progress in Neuro-Psychopharmacology & Biological Psychiatry 30.7 (Sept. 2006): 1271–76.
Kelly Karpa, R.Ph., PhD
Ruth A. Wienclaw, PhD
Venlafaxine
Venlafaxine
Definition
Venlafaxine is an antidepressant available in the United States under the trade name of Effexor or Effexor XR.
Purpose
Venlafaxine is used to treat depression and generalized anxiety disorder . It has also been used to treat obsessive-compulsive disorder and irritable bowel syndrome.
Description
Venlafaxine is an antidepressant. It has actions common to both the cyclic antidepressants such as imipramine (Tofranil) and amitriptyline (Elavil,) and the selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine (Prozac), sertraline (Zoloft), and paroxetine (Paxil). It is believed to derive its actions by increasing levels of both norepinephrine and serotonin in the brain .
The therapeutic effects of venlafaxine, like other antidepressants, appear slowly. Maximum benefit is often not evident for at least two weeks after starting the drug. People taking venlafaxine should be aware of this and continue taking the drug as directed even if they do not see immediate improvement.
Venlafaxine is broken down by the liver and eliminated from the body by the kidneys. As a result, the dose of venlafaxine must be lowered in people with liver or kidney disease.
Venlafaxine is available in 25-mg, 37.5-mg, 50-mg, 75-mg, and 100-mg rapid-release tablets and 75-mg and 150-mg extended-action capsules.
Recommended dosage
The recommended initial dose of venlafaxine is 75 mg daily taken as two or three equal doses. The dose may be increased in 75-mg increments every four days as needed until symptoms of depression or anxiety resolve. Most commonly, dosages range between 150 mg to 225 mg daily. although in severe situations, 375 mg per day may be needed. Once patients are stabilized using the rapid-acting tablets, they may be converted over to the appropriate dose of extended-release capsules.
In people with liver disease, the daily dosage of venlafaxine should be cut in half. In patients with kidney disease, the daily dosage of venlafaxine should be reduced 25–50%, depending upon the extent of kidney damage. When stopping venlafaxine, the dosage should be reduced gradually over a period of at least two weeks before the drug is totally stopped.
Precautions
Patients taking venlafaxine should be monitored closely for insomnia , anxiety, mania, significant weight loss, seizures , and thoughts of suicide .
Caution should also be exercised when prescribing venlafaxine to patients with impaired liver or kidney function, the elderly (over age 60) children, individuals with known manic-depressive disorder or a history of seizures, people with diabetes, and individuals expressing ideas of committing suicide.
Individuals should not take MAO inhibitors such as Nardil during venlafaxine therapy, for two weeks prior to beginning venlafaxine therapy, and for five weeks after stopping venlafaxine therapy.
Care should be taken to weigh the risks and benefit of this drug in women who are, or wish to become, pregnant, as well as in breast-feeding mothers.
People with diabetes should monitor their blood or urine sugar more carefully, since venlafaxine may affect blood sugar.
Until an individual understands the effects that venlafaxine may have, he or she should avoid driving, operating dangerous machinery, or participating in hazardous activities. Alcohol should not be used while taking venlafaxine.
Side effects
More common side effects include decreased sexual drive, restlessness, difficulty sitting still, skin rash, hives, and itching.
Less common side effects include fever and/or chills, and pain in joints or muscles.
Rare side effects include pain or enlargement of breasts and/or abnormal milk production in women, seizures, fast heart rate, irregular heartbeats, red or purple spots on the skin, low blood sugar and its symptoms (anxiety, chills, cold sweats, confusion, difficulty concentrating, drowsiness, excess hunger, rapid heart rate, headache, shakiness or unsteadiness, severe fatigue ), low blood sodium and its symptoms (including confusion, seizures, drowsiness, dry mouth, severe thirst, decreased energy), serotonin syndrome (usually at least three of the following: diarrhea, fever, sweatiness, mood or behavior changes, overactive reflexes, fast heart rate, restlessness, shivering or shaking), excitability, agitation, irritability, pressured talking, difficulty breathing, and odd body or facial movements.
Interactions
Venlafaxine interacts with a long list of other medications. Anyone starting this drug should review the other medications they are taking with their physician and pharmacist for possible interactions. Patients should always inform all their health care providers, including dentists, that they are taking venlafaxine.
Dangerously high blood pressure, rapid changes in heart rate, high fever, muscle stiffness, and sudden muscle spasms have resulted from the combination of antidepressants, such as venlafaxine, and members of another class of antidepressants known as monoamine oxidase (MAO) inhibitors. Because of these serious adverse reactions, venlafaxine should never be taken in combination with MAO inhibitors. Patient taking any MAO inhibitors, for example Nardil (phenelzine sulfate) or Parmate (tranylcypromine sulfate), should stop the MAO inhibitor then wait at least 14 days before starting venlafaxine or a tricyclic antidepressant. The same holds true when discontinuing venlafaxine and starting an MAO inhibitor.
Some other drugs such as trazodone (Desyrel), sibutramine (Meridia), and sumatriptan (Imitrex) also interact with venlafaxine and cause a syndrome known as neuroleptic malignant syndrome, characterized by irritability, muscle stiffness, shivering, muscle spasms, and altered consciousness.
The sedative effects (drowsiness, lack of mental clarity) of venlafaxine are increased by other central nervous system depressants such as alcohol, sedatives, sleeping medications, or other medications used for mental disorders such as schizophrenia .
Resources
BOOKS
Facts and Comparisons Staff. Drug Facts and Comparisons. 6th Edition. St. Louis, MO: Facts and Comparisons,2002.
Mosby Staff. Mosby's Medical Drug Reference. St. Louis, MO: Mosby, Inc, 1999.
Wyeth Laboratories Staff. Effexor Package Insert. Philadelphia, PA: Wyeth Laboratories, 2001.
Kelly Karpa, RPh, Ph.D.