Prozac - (Fluoxetine)

Prozac is sometimes used together with another medication called olanzapine (Zyprexa) to treat depression caused by bipolar disorder (manic depression). This combination is also used to treat depression after at least 2 other medications have been tried without successful treatment of symptoms.

How does it work?

Prozac capsules and liquid contain the active ingredient fluoxetine, which is a type of antidepressant known as a selective serotonin reuptake inhibitor (SSRI). (NB. Fluoxetine is also available without a brand name, ie as the generic medicine.)

Antidepressant medicines act on nerve cells in the brain. In the brain there are numerous different chemical compounds called neurotransmitters. These act as chemical messengers between the nerve cells. Serotonin is one such neurotransmitter and has various functions that we know of.

When serotonin is released from nerve cells in the brain it acts to lighten mood. When it is reabsorbed into the nerve cells, it no longer has an effect on mood. It is thought that when depression occurs, there may be a decreased amount of serotonin released from nerve cells in the brain.

SSRIs work by preventing serotonin from being reabsorbed back into the nerve cells in the brain. This helps prolong the mood lightening effect of any released serotonin. In this way, fluoxetine helps relieve depression.

Fluoxetine may also be used in the treatment of bulimia nervosa and obsessive compulsive disorder in adults. It is not fully understood how fluoxetine works in these illnesses.

It may take between two to four weeks for the benefits of this medicine to appear, so it is very important that you keep taking it, even if it doesn't seem to make much difference at first. If you feel your depression has got worse, or if you have any distressing thoughts or feelings in these first few weeks, then you should talk to your doctor.

When and how do I take it?

Fluoxetine (Prozac) comes as a capsule, a tablet, a delayed-release (long-acting) capsule, and a solution (liquid) to take by mouth. Fluoxetine may be taken with or without food. Fluoxetine (Prozac) capsules, tablets, and liquid are usually taken once a day in the morning or twice a day in the morning and at noon. Fluoxetine delayed-released capsules are usually taken once a week. Take fluoxetine at around the same time(s) every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take fluoxetine exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

What’s the dose?

Usual Adult Dose of Fluoxetine for Premenstrual Dysphoric Disorder:

• Initial dose: 20 mg orally once daily.
• Maintenance dose: 20 mg/day continuously or, alternatively, 20 mg/day during the luteal phase of the menstrual system (the 14 days prior to the anticipated start of menses). The 20 mg/day dosage has been shown to be effective for up to six months of treatment. A 60 mg/day dosage has also been studied, but has not been shown to be significantly more effective than 20 mg/day.
• Maximum dose: 80 mg/day.

Usual Adult Dose of Fluoxetine for Depression:

Immediate-release capsules or tablets:

• Initial dose: 20 mg orally once a day in the morning.
• Maintenance dose: 20 to 80 mg/day in 1 to 2 divided doses.

Extended-release capsules: Patients taking 20 mg daily may be converted to 90 mg orally once a week. The first weekly dose should be given 7 days after the last daily dose.

Usual Adult Dose of Fluoxetine for Obsessive Compulsive Disorder:

• Initial dose: 20 mg orally once a day in the morning.
• Maintenance dose: 20 to 60 mg/day in 1 to 2 divided doses.
• Maximum dose: 80 mg/day.

Usual Adult Dose of Fluoxetine for Panic Disorder:

• Initial dose: 20 mg orally once a day in the morning.
• Maintenance dose: 20 to 60 mg/day in 1 to 2 divided doses.
• Maximum dose: 80 mg/day.

Usual Adult Dose of Fluoxetine for Bulimia:

• Initial dose: 60 mg orally once a day in the morning. Some patients have started with lower doses. Doses greater than 60 mg/day have not been systematically studied.

Usual Pediatric Dose of Fluoxetine for Depression:

Major depression:

7 years or younger:
Safety and efficacy have not been established.

8 years to less than 18 years:
Initial dose: 10 to 20 mg orally once daily. After 1 week at 10 mg/day, the dose should be increased to 20 mg/day.

Lower weight children:
Due to higher plasma levels in lower weight children, the starting and target dose in this group should generally be 10 mg/day. A dose increase to 20 mg/day may be considered after several weeks if clinical improvement is insufficient.

Usual Pediatric Dose of Fluoxetine for Obsessive Compulsive Disorder:

6 years or younger:
Safety and efficacy have not been established.

7 years to less than 18 years:
Initial dose: 10 mg orally once daily.

Adolescents and higher weight children:
After 2 weeks at 10 mg/day, the dose should be increased to 20 mg/day. Additional dose increases may be considered after several more weeks if clinical improvement is insufficient. A dose range of 20 to 60 mg/day is recommended.

Lower weight children:
Additional dose increases may be considered after several weeks if clinical improvement is insufficient. A dose range of 20 to 30 mg/day is recommended. There is minimal experience with doses greater than 20 mg/day and none with doses greater than 60 mg/day.

Could it interact with other tablets?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to ensure that the combination is safe.

Fluoxetine must not be taken at the same time as monoamine oxidase inhibitor antidepressants (MAOIs) such as phenelzine, isocarboxazid or tranylcypromine, or with selegiline or rasagiline, which are also MAOIs and are used to treat Parkinson's disease. If you have been taking one of these MAOIs you should not start treatment with fluoxetine until at least 14 days after stopping the MAOI. Treatment with an MAOI, or with the related antidepressant moclobemide, should not be started until at least five weeks after fluoxetine has been stopped.

Fluoxetine may increase the blood levels of the following medicines, and your doctor may consequently reduce the dose of these if you are taking them with fluoxetine, or if you have taken fluoxetine in the previous five weeks:

• aripiprazole
• atomoxetine
• carbamazepine
• clozapine
• flecainide
• haloperidol
• tricyclic antidepressants such as imipramine, amitriptyline, clomipramine, desipramine
• phenytoin
• benzodiazepines such as diazepam or alprazolam. (If these are taken with fluoxetine there may be an increased chance of drowsiness.)

If fluoxetine is taken with lithium it may cause the blood level of lithium to rise, or there may be an increased risk of side effects. The combination should only be used with caution.

There may be an increased risk of side effects if fluoxetine is taken with the following, which also enhance the activity of serotonin in the brain:

• duloxetine
• rasagiline
• sibutramine
• the herbal remedy St John's wort (Hypericum perforatum) - – this should not be taken in combination with fluoxetine
• triptans for migraine, eg sumatriptan
• tramadol
• tryptophan.

Fluoxetine may increase the effect of anti-blood-clotting medicines (anticoagulants) such as warfarin, and this may increase the risk of bleeding. If you are taking an anticoagulant with this medicine, your blood clotting time (INR) should be regularly monitored.

Fluoxetine can reduce the effectiveness of tamoxifen and as a result it should be avoided wherever possible in people taking tamoxifen.

As SSRIs have been associated with bleeding abnormalities, the following medicines, which are known to affect the ability of the blood to clot, should be used with caution in people taking fluoxetine because the combination may carry an increased risk of causing bleeding:

• antiplatelet medicines such as aspirin, clopidogrel or dipyridamole
• non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or diclofenac
• some antipsychotic medicines
• some antisickness medicines, eg prochlorperazine
• tricyclic antidepressants, eg amitriptyline.

Treatment with this medicine may alter control of blood sugar in people with diabetes, who may need an adjustment in their dose of insulin or antidiabetic tablets. People with diabetes should discuss this with their doctor.

There may be an increased risk of side effects if fluoxetine is taken with antipsychotic medicines such as haloperidol.

What are the possible risks or side-effects?

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.

Very common (affect more than 1 in 10 people)

• Difficulty sleeping (insomnia).
• Headache.
• Feeling sick (nausea).
• Diarrhoea.
• Fatigue.

Common (affect between 1 in 10 and 1 in 100 people)

• Decreased appetite and weight loss.
• Dry mouth.
• Anxiety, nervousness and restlessness.
• Feeling jittery.
• Decreased sex drive.
• Problems with getting an erection or ejaculation.
• Abnormal dreams.
• Dizziness.
• Change in taste.
• Feeling sleepy or lethargic.
• Blurred vision.
• Awareness of your heart beat (palpitations).
• Flushing.
• Yawning.
• Indigestion.
• Vomiting.
• Increased sweating.
• Rash or itching.
• Frequent urination.
• Aching joints.

Uncommon (affect between 1 in 100 and 1 in 1000 people)

• Problems with orgasm.
• Problems with co-ordination or balance.
• Tremor or twitching.
• Dilated pupils.
• Low blood pressure.
• Hair loss.
• Increased tendency to bruise.
• Feeling hot, cold or generally unwell.

Rare (affect between 1 in 1000 and 1 in 10,000 people)

• Unpleasant sensation of restlessness that causes an inability to sit still (akathisia - see warning section above).
• Convulsions.
• Mania.
• Hallucinations.
• Panic attacks.
• Abnormal reaction of the skin to light (photosensitivity).
• Milky secretion from the breasts (galactorrhoea).
• Difficulty passing urine.

The side effects listed above may not include all of the side effects reported by the medicine's manufacturer. For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

Can I drink alcohol while taking it?

Since alcohol and Prozac (fluoxetine hydrochloride) act upon similar chemicals in the brain, the antidepressant may intensify the effects of alcohol. However, many healthcare providers say that, in general, it is okay to drink alcohol while on Prozac, as long as it's in moderation -- and only after you are aware of the effects that the medication may have on your body.

What if I’m pregnant/breastfeeding?

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

• This medicine can be used during pregnancy, but only with caution and if the benefits to the mother outweigh any risks to the foetus. This is particularly important in the first and third trimester and prior to and during labour. The medicine may cause fluoxetine-type side effects or withdrawal symptoms in the newborn baby if used in late pregnancy. It is important to seek medical advice from your doctor if you get pregnant or plan to have a baby while taking this medicine, so that you can discuss the potential risks to the baby if you keep taking the medicine, compared with the risks of stopping treatment.
• This medicine passes into breast milk and may have adverse effects on a nursing infant. Mothers who need to take this medicine should discuss the risks and benefits of breastfeeding with their doctor.

Remember to keep all medicines out of reach of children
Please Note: We have made every effort to ensure that the content of this information sheet is correct at time of publish, but remember that information about drugs may change. This sheet does not list all the uses and side-effects associated with this drug. For full details please see the drug information leaflet which comes with your medicine. Your doctor will assess your medical circumstances and draw your attention to any information or side-effects which may be relevant in your particular case.

References:

1. Medicines.ie website- prozac SPC http://www.medicines.ie/medicine/3639/SPC/Prozac+Tablets/

2. Medicines.ie- prozac PIL http://www.medicines.ie/medicine/8293/PIL/Prozac+Tablets/