Venlafaxine is in a class of drugs called antidepressants. It works by altering chemicals in the brain that may become unbalanced and cause depression, panic, or anxiety.
Indications for its use are major depressive disorder, anxiety, and panic disorder.
You may have an increased risk of suicidal thoughts or behavior at the start of treatment with an antidepressant medication, especially if you are less than 18 years old. Talk with your doctor about this risk. You will need to be monitored for worsening symptoms of depression and/ or suicidal thoughts during the first weeks of treatment, or whenever your dose is changed. It is important for you to have regular visits to your doctor for at least the first 12 weeks of treatment.
Before taking venlafaxine, tell your doctor if you have: cirrhosis or other liver disease;
kidney disease; a family or personal history of bipolar disorder (manic depression);
a family or history of suicidal thoughts or actions; high blood pressure; glaucoma;
seizures or epilepsy; a bleeding or blood clotting disorder; diet pills; or high cholesterol.
If you have any of the conditions listed above, you may not be able to take venlafaxine, or you may need a dosage adjustment or special monitoring during treatment.
Venlafaxine may be harmful to an unborn baby. It can also pass into breast milk and can harm a nursing baby. Similar medicines have caused problems in newborn babies of mothers who used the drug during the third trimester of pregnancy. Tell your doctor if you are pregnant or plan to become pregnant during treatment. Older adults may be more sensitive to the side effects of this medication.
Do not stop using venlafaxine without first talking to your doctor. You may have unpleasant side effects if you stop taking this medication suddenly. It may take 4 weeks or more for you to start feeling better.
Seek emergency medical attention if you think you have taken too much of this medication. Symptoms of a venlafaxine overdose may include dizziness, sleepiness, nausea, and numbness or tingling in your hands or feet.
Avoid drinking alcohol, which can increase some of the side effects of venlafaxine.
Avoid also using other medicines that make you sleepy (such as cold medicine, pain medication, muscle relaxants, other antidepressants, and medicine for seizures). They can add to sleepiness caused by venlafaxine. Venlafaxine can cause side effects that may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be awake and alert.
Get emergency medical help if you have any of these signs of an allergic reaction: skin rash or hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Contact your doctor promptly if you have any of the following side effects, especially if they are new symptoms or if they get worse: mood changes, anxiety, panic attacks, trouble sleeping, irritability, agitation, aggressiveness, severe restlessness, mania (mental and/ or physical hyperactivity), and thoughts of suicide or hurting yourself. Other serious side effects are: feeling light-headed, fainting; increase blood pressure (severe headache, blurred vision); seizure (convulsions); or fast or slow heartbeat.
Other less serious side effects are more likely to occur, such as: drowsiness or dizziness;
nervousness or anxiety; dry mouth; nausea, vomiting, diarrhea, constipation; decreased sex drive, impotence, or difficulty having an orgasm; headache, blurred vision; sleep problems; tremor or chills; increased sweating; or changes in appetite or weight. Talk to your doctor about any other unusual side effects.
Do not take venlafaxine together with a monoamine oxidize inhibitor (MAOI) such as isocarboxazid (Marplan), phenelzine (Nardil), selegiline (Eldepryl), or tranylcypromine (Parnate). You must wait at least 14 days after stopping an MAOI before you can take venlafaxine. You must wait at least 7 days after you stop taking venlafaxine before you start taking an MAO inhibitor.
Before taking venlafaxine, tell your doctor if you are using any of the following medicines: diet pills; diuretics; cimetidine (Tagamet, Tagamet HB); warfarin (Coumadin); amiodarone (Cordarone), quinidine (Quinadex, Cardioquin, Quinaglute), mibefradil (Posicor); methadone (Dolophine, Methadose); HIV medicines such as indinavir (Crixivan), ritonavir (Norvir); saquinavir (Invirase), nelfinavir (Viracept);
haloperidol (Haldol) or risperidone (Risperdal); or other antidepressants such as clomipramine (Anafranil), desipramine (Norpramin), duloxetine (Cymbalta), fluoxetine (Prozac), paroxetine (Paxil), buproprion (Wellbutrin, Zyban). If you are using any of these drugs, you may not be able to use venlafaxine, or you may need dosage adjustments or special tests during treatment. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors.
Venlafaxine is a structurally novel antidepressant for oral administration. It is designated (R/S)-1-[2-(dimethylamino)-1- (4-methoxyphenyl)ethyl] cyclohexanol hydrochloride or (±)-1-[a-[(dimethyl-amino)methyl]- p-methoxybenzyl] cyclohexanol hydrochloride and has the empirical formula of C17H27NO2 HCl. Its molecular weight is 313.87. Compressed tablets contain venlafaxine hydrochloride equivalent to 25 mg, 37.5 mg, 50 mg, 75 mg, or 100 mg venlafaxine. Inactive ingredients consist of cellulose, iron oxides, lactose, magnesium stearate, and sodium starch glycolate.
Venlafaxine has the following structural formula: