Duloxetine (Cymbalta)

Duloxetine (Cymbalta)

What is Duloxetine used for?

Known by their brand names Cymbalta and Irenka, Duloxetine is a prescription medication used for the treatment of anxiety (generalised anxiety disorder) and depression (major depressive disorders) as an antidepressant, as well as for pain management associated with diabetes (diabetic peripheral neuropathy) due to nerve damage, and chronic pain conditions affecting the muscles and bones, such as fibromyalgia, Rheumatoid arthritis or chronic back pain.

Duloxetine chemical structure: Atoms are represented as spheres with conventional colour coding - hydrogen (white), carbon (grey), nitrogen (blue), sulfur (yellow), oxygen (red).The medication is classified as a selective serotonin and norepinephrine reuptake inhibitor (SSNRI) and effectively works by balancing the production of serotonin and norepinephrine (chemicals) in the brain. The balance helps to treat more severe symptoms of depression and anxiety (not recommended for ‘the blues’), as well as inhibit pain signals from nerves in the body to the brain.

Duloxetine is typically prescribed in delayed-release capsule form, taken orally. The medication can help to improve sleep, problems with appetite, mood or energy levels, as well as alleviate issues of restlessness. It is also beneficial for alleviating pain caused by various medical conditions.

The medication is available as a generic drug in some strengths, but not in all. If opting for a generic version, which is usually more cost effective, it is advisable to consult your doctor for the best option to include on your prescription.

Precautions and considerations for taking this medication

Only a doctor may prescribe this medication, and will generally do so once a full assessment of your physical condition has taken place. A doctor will prescribe such a medication if the benefits outweigh possible side-effects of use.

A prescription will be considered, as well as the dosage, strength (milligrams) and how often the medication is necessary to be taken based on the following factors:

  • Your diagnosed condition
  • How severe your condition is
  • Your reaction to the initial prescribed dose

Some other things a doctor will consider in detail before prescribing this medication include:

  • Allergies and allergic reactions: It is very important for your doctor to be well aware of any past adverse reactions or current allergies you may have prior to taking this medication. Allergies can include medications, animals, foods, preservatives or dyes. If you have a history of allergic reactions your doctor will carefully assess your level of risk in taking this medication before prescribing it to you. Serious allergic reactions can occur when taking duloxetine and can include hives, problems with breathing and swelling of the tongue or throat.
  • Age: A doctor will need to consider a patient’s age when it comes to safety of use. To date, studies have not shown that this medication can safely be taken by children younger than 7 years of age, especially when treating generalised anxiety disorder. The medication has also not been noted as effective for the treatment of major depressive disorder in children under the age of 18. Seniors (65 years and older) can take this medication, but may be more sensitive to side-effects, especially blood pressure changes and reduced levels of sodium (salt) in the bloodstream (hyponatremia). Symptoms of this in seniors include headaches, balance problems and unsteadiness, body weakness, confusion, memory and concentration problems. As such the medication may be prescribed with caution and at lower dosages.
  • Pregnancy: No conclusive studies have been conducted with pregnant females using this medication. Animal studies, have however, shown some adverse effects on a foetus during all trimesters (gestation period). As such this medication is classified as a category C drug. A doctor may not recommend this medication during pregnancy, unless the benefits justify usage. A woman who is or who plans to fall pregnant must disclose this to her doctor before using the medication. Babies born to mothers who have used the medication during the last 3 months of pregnancy can develop withdrawal symptoms. These can include muscle stiffness, constant crying, feeding or breathing problems and seizures. All symptoms must be reported to a doctor immediately for assessment and prompt treatment.
  • Infants and breastfeeding: As with pregnancy, adequate studies to determine potential risk to a new-born baby during breastfeeding have not been conducted. A doctor may prescribe this medication to a new mother if the benefits outweigh possible side-effects and risk while breastfeeding. Both mother and baby may need to be monitored periodically while the medication is being used as the drug may be passed through breast milk. A doctor may also recommend a choice between using the drug and breastfeeding. Every case will be treated with caution and utmost care before recommending this drug.
  • Medication interactions: Interaction refers to a change in the way a drug is designed to work, preventing it from serving its purpose. A doctor will need to know if you are taking any other medications or supplements (including vitamins and herbal products) before prescribing this drug. The taking of multiple medications or supplements will need to be carefully managed. Your doctor will need to assess all benefits and risks associated with taking different medications. Some medications may not be taken at the same time at all, while others can be used with caution and controlled with specific dosages. If you need to take other medications, a doctor will assess whether the combination is safe, or change medications and adjust dosages accordingly. Your doctor will be looking to assess whether you are taking any medications that will have adverse effects in serotonin. If other medications that affect serotonin are being taken, you can be at increased risk of serotonin syndrome, a potentially life-threatening condition that is triggered by excess nerve cell activity. Medications used to treat schizophrenia and other mental health conditions, NSAIDS (non-steroidal anti-inflammatory medications), anticoagulants (blood thinning medications), iron toxicity medications, drugs for the treatment of Gaucher disease (a rare genetic disorder), as well as others for managing cancer and the discontinuation of smoking can all cause unwanted side-effects if taken together. These side-effects can include problems such as an abnormal heart rate (or arrhythmia) and other heart related problems, abnormal bleeding, and an increased risk of seizures. All potential side-effect risks must be taken seriously before any prescription is given. If you have taken monoamine oxidase inhibitor (MAO) medications (particularly for the treatment of psychiatric disorders) two weeks (14 days) prior, your doctor will advise against taking duloxetine. It will also be made very clear not to take any MAOs within at least 5 days following discontinuation of this medication as well. Interactions between the medications can lead to side-effects such as confusion, restlessness and agitation, intestinal or stomach troubles, extremely high blood pressure (hypertension), sudden convulsions or a high body temperature, among various other complications.
  • Other interactions: A doctor may also question you about your use of alcohol or tobacco before prescribing this medication. If you are a smoker and a moderate drinker your doctor may recommend certain use instructions, as well as a specific dose that is least likely to result in adverse reactions. Your doctor may also bring to your attention to possible interactions with specific types of food. Excessive drinking habits and the taking of duloxetine are not recommended and can result in serious damage to the liver.
  • Other medical conditions: Certain medical conditions may mean that this medication cannot be prescribed. Others may mean that very specific dosages need to be prescribed for safe usage. It is vital that you disclose any of the following conditions to your doctor before accepting a prescription – kidney disease, liver disease (including cirrhosis), alcohol abuse (including a history of it), problems with bleeding, bipolar disorder, mania (including a history of this), diabetes, glaucoma, problems with digestion, hypertension, heart disease, hyponatremia (low sodium levels in the blood), problems with urination, and seizures (including a history of these). Those with a liver or kidney condition may experience difficulty with clearing the medication from the body, thus causing more damage to the organs. If you have bladder problems or trouble with urination flow, the use of the medication may worsen such symptoms. Those with diabetes will need very specific care and monitoring while taking the medication as it can have adverse effects on blood sugar levels.

Female doctor filling out a medical form (prescription) on a clipboard

How to use Duloxetine

If a doctor has prescribed this medication for use, it is very important to use exactly as directed. You will be strongly advised to take the exact dosage, at specific times and not to take the medication for a longer period of time than is ordered.

Your doctor will recommend that you familiarise yourself with the medication guide or instruction leaflet that comes with the medication. If you have any concerns or questions, it is advisable to consult your doctor for clarity.

Duloxetine is generally taken orally and must be swallowed whole, with or without the accompaniment of food. No capsule should be crushed, chewed or broken before swallowing. The capsule and its contents must remain intact and not opened and sprinkled on food or in liquid before being ingested. The medication is designed to be released slowly into the body. Releasing all of the drug into the body at once encourages the medication to get to work faster than it is meant to and thus leads to adverse effects.

Your doctor will also likely explain the effects of the medication. It is not likely that you will begin to feel beneficial effects immediately after starting treatment. It may take a few weeks for the medication to begin working effectively in the body. For this reason, your doctor will advise you to continue use as prescribed, even if it takes several weeks for you to feel any real effect.

It will also be recommended that you take the medication for a set period of time even if you begin to feel well. It is very important not to discontinue use without the express knowledge or recommendation of your doctor. Some medical conditions can worsen with sudden discontinuation. You can also experience certain drug side-effects or worsening symptoms.

Whatever physical changes (symptoms) you experience on this medication, it is strongly advisable to keep your doctor in the loop. He or she can effectively adjust your dosages to either gradually reduce or alleviate side-effects altogether. If the medication does not take effect or your feel considerably worse, you should consult your doctor as soon as possible so that treatment can be reassessed.

Proper use of this medication will involve:

  • Correct dosages: The prescribed doses to be taken and how often differs from one patient to another. Your doctor will prescribe specific dosage instructions with your medical condition in mind. It can happen that your prescribed dose is different to that which is recommended on the medication guide. If this concerns you, speak with your doctor so that he or she can advise reasons why. It is not advisable to adjust your dosage on your own. The dosage amount prescribed also depends on the strength of the medication, your age, as well as the condition being treated. Lower doses (such as 30 milligrams a day or 20 milligrams twice a day) may be recommended at first and then increased as necessary. Duloxetine comes in strengths of 20 mg, 30 mg, 40 mg and 60 mg (milligrams). Dosages usually don’t exceed 120 mg (milligrams) a day.
  • Missed dosages: It can happen that a dose is skipped or missed. If the realisation of missing a dose happens close to the time of the next dose, it is important to skip the missed dose and take the next one. You should not to double up the dose in order to ‘make up’ for the missed one. Double doses will lead to potentially serious side-effects. If it is not yet close to time for the next dose, take the missed dose as soon as possible, and continue as normal.
  • Medication storage: Duloxetine (Cymbalta) is best stored in a closed, dry container or cupboard at room temperature, away from direct light, moisture or heat. This medication should not be frozen or be placed within reach of children or pets. It should also not be shared with anyone else. It is not recommended to keep any medication beyond the package expiry date. All expired or unused medication must be discarded if treatment with the drug is discontinued.

Important warnings and side-effects

Food and Drug Administration (FDA) warnings

The FDA has allocated a ‘black box warning’ for this medication which effectively alerts both medical professionals and patients that the drug carries potentially dangerous side-effects for some individuals. All doctors prescribing this medication will know this and take extra care when recommending the medication to certain individuals. A black box warning medication is always used with care and taken very seriously.

The warning relates to documented side-effects that have noted an increased risk of suicide and associated behaviours in those being treated for a major depressive disorder, aged 24 and younger. It has also been noted that during the initial stages of treatment, symptoms of depression can worsen and lead to thoughts of suicide. Teenagers and young adults may become highly agitated, irritable and more depressed. Some have trouble sleeping, engage in reckless behaviours, get upset easily or experience a spike in energy levels. Any such symptoms should be reported to your doctor right away.

Before any prescription is recommended for treatment your doctor will check both your personal and family history of possible psychiatric disorders. If there is any history of manic-depressive or bipolar disorder, or instances of suicidal attempts (including successful suicides), he or she may not recommend this medication.

The medication is also capable of causing severe drowsiness which can impair the ability to make sound decisions, think or react clearly and quickly. It is not recommended that anyone on this medication be allowed to drive or operate heavy or potentially dangerous machinery (at least until the body has settled on the drug and a doctor has assessed you as ‘well-adjusted’ on the medication).

The warning also relates to a potentially serious complication known as serotonin syndrome. Side-effects include confusion and agitation, sweating, loss of coordination, as well as an increased heart rate and blood pressure. If severe, this condition can be fatal. A sudden drop in blood pressure is also potentially problematic and is included in the warning as well.

General side effects and potential complications

Taking this medication to treat a condition is not without some side-effects. Your doctor will have weighed the benefits against possible side-effects before prescribing the medication. The benefit must be greater than the risk. Normally, side-effects experienced are not serious and typically occur in the initial stage of treatment or during dosage changes as the body adjusts. Your doctor will help you to manage side-effects throughout your treatment.

The list of noted side-effects is not applicable to all, but any that are experienced must be reported to your doctor as soon as possible, so as to avoid any potential damage or medical complications. Some are considered more serious than others and could indicate damage to the liver, changes in blood pressure levels, serotonin syndrome or abnormal bleeding in the body.

It is not unusual for you to experience changes in blood pressure while on this medication. Your doctor will request follow-ups periodically to check for any higher than normal levels.

Young woman in pain, sitting on a bed.The list of side-effects includes:

  • Headache
  • Skin rashes, blisters, peeling of the skin or severe acne
  • Inflamed skin (redness) or lesions (red with a purplish centre)
  • Itching, welts or hives on the skin (the face, eyelids, tongue, lips, throat, limbs, hands, feet and sex organs), as well as swelling (puffiness) on or around the eyes, lips, tongue or face
  • Swelling of the face, hands and ankles
  • Ulcers, sores or white spots on the lips or inside the mouth
  • Unpleasant breath odour
  • Dry mouth
  • Changes in ability to taste (or loss of taste)
  • Breathing problems
  • Yellowing of the eyes and skin (jaundice)
  • Abdominal pain
  • Tightness in the chest
  • Vomiting of blood or substances that resemble dark coffee grounds
  • Visual disturbances (such as blindness, widened pupils, decreased vision or blurred vision)
  • Eye pain and inflammation (redness of the eyes)
  • Eye tearing
  • Ear congestion
  • Sore throat
  • Runny or stuffy nose
  • Body chills and cold sweats
  • Noticeable changes in consciousness or loss of consciousness
  • Convulsions, seizures, twitching muscles or tremors (shaking)
  • Confusion, light-headedness and dizziness
  • Feeling faint
  • Fatigue, drowsiness and body weakness
  • Difficulty with swallowing
  • Coughing
  • Clay-coloured or light coloured stools (faeces)
  • Black or bloody stools (faeces)
  • Constipation or diarrhoea
  • Bowel movement difficulties or loose stools
  • Problems with urination (dark urine, difficulties with urinating or decreased urine flow)
  • A fast or irregular heartbeat
  • Sweating (increased or profuse)
  • Bruising or bleeding easily
  • Increased thirst
  • Joint and muscle pain, muscle cramps or stiffness
  • Swollen joints
  • Movement difficulties
  • Loss of appetite
  • Lack of libido (interest in sex or changes in sexual ability such as abnormal orgasms, problems with the discharge of semen or ejaculation or the inability to have or maintain an erection)
  • Persistent nausea and vomiting
  • Hallucinations
  • Unexplained fever
  • Unexplained weight loss or decreased weight
  • Coma
  • Manic episodes (including severe sleeping problems, racing thoughts, increased energy levels, reckless behaviour, excessive agitation, irritability or happiness, unusually grand ideas, and excessive talking or faster than usual)
  • Belching
  • An acidic or sour stomach
  • Sensations of crawling, burning, itching, prickling, tingling or numbness
  • Heartburn and indigestion

Signs of overdose

Symptoms experienced with overdose require emergency medical attention. These include:

  • Fever
  • Diarrhoea (especially in children)
  • Loss of bladder control
  • Severe agitation
  • Overactive reflexes, muscle spasms, twitching, trembling, jerking in the extremities, shivering and restlessness
  • Vomiting
  • Profuse or increased sweating
  • Unexplained drowsiness, fatigue, weakness, sleepiness and poor coordination
  • Sudden loss of consciousness
  • Uncontrolled behaviour (talking or acting with excitement)

Withdrawal symptoms

Many individuals do experience side-effects of discontinuation. Withdrawal symptoms are to be expected and your doctor will likely warn you of the following possibilities, as well as help you to best manage them:

  • Headaches
  • Dizziness
  • Nausea and vomiting
  • Fatigue or lethargy
  • Irritability or anxiety
  • Sleeping problems or insomnia
  • Excessive sweating (hyperhidrosis)
  • Diarrhoea
  • Seizures
  • Paraesthesia (electric shock or prickling sensations, also known as ‘brain zaps’ or ‘lightning bolt syndrome’)
  • Nightmares
  • Personality changes, extreme mood swings and emotional lability (pathological laughing or crying)
  • Ringing in the ears (tinnitus)

Not all symptoms may be experienced and those that are range from mild to severe, as well as for different durations. It is highly likely that you will remain in close contact with your doctor from the time of prescription, through your treatment period and during discontinuation. He or she will conduct checks periodically and ensure that you are well adjusted on (and off) the medication.

If any new symptoms develop or you feel concerned, it is advisable to consult your doctor to discuss as soon as possible.

What else should I take into consideration regarding this medication?

  • Refills: Your doctor will prescribe dosages which will require periodic refills. The number of authorised refills will be written on your original prescription for the pharmacist to make note of and dispense accordingly. It is not likely that you will require a new prescription each time a refill is needed.
  • Travelling during treatment: If you travel during your treatment period, it is advisable to carry the medication either on you or in your carry-on luggage. Airport X-ray machines are not likely to interfere with your medication. In some instances, you may need to carry the dispensing pharmacy’s re-printed label as a form of identification. You can also carry the original prescription box (with label) as well, and present it if necessary.
  • Medical health insurance: If you are a member of a medical health insurance plan, it may be possible that your medication will be covered. You will need to check this with your provider. Most may request prior authorisation approval before you commence treatment using this medication.
  • Clinical monitoring: You may be requested to attend periodic clinical monitoring sessions, especially if you are using this medication as an antidepressant for a major depressive disorder. You may need to be assessed for worsening depressive behaviours or symptoms, especially those associated with suicidal thoughts.

Is Duloxetine (Cymbalta) a controlled substance?

Duloxetine is not classified as a scheduled drug under the Controlled Substance Act (even though it is a prescription medication which can only be authorised by a licensed medical practitioner) as it isn’t considered one that runs any risk of abuse or dependency.

Duloxetine is, in a sense, a controlled substance since it can only be obtained through prescription by a medical doctor. Since there is little evidence that the medication runs any risk of dependency, it is not considered to be a narcotic substance requiring regulation by the Controlled Substance Act in the United States.

Is Duloxetine addictive?

The nature of withdrawal symptoms linked to duloxetine is not to be confused with those associated with narcotic abuse (and discontinuation of illicit drugs). Withdrawal symptoms are generally known as ‘discontinuation syndrome’ and are not experienced due to any form of addiction to the medication.

Instead, withdrawal occurs as a result of the necessary adjustment of cell receptors in the brain. Serotonin and other chemicals in the brain lower with discontinuation, thus causing a variety of side-effects as the body adjusts to a lack of the medication in the system.

Side-effects and symptoms of withdrawal can occur more severely than many other medications, particularly in antidepressant drugs, because the substance typically leaves the bloodstream fairly quickly once discontinued. Slower expulsion of a substance from the body tends to result in fewer or less severe side-effects.

If you are using Cymbalta for a long period, withdrawal symptoms may range from mild to severe and can linger for several weeks following discontinuation of the drug. In some instances, it can take around 6 to 8 weeks to safely discontinue treatment on this medication.

The potential for severe withdrawal is one reason why doctors will urge you to adhere to their strict dosage instructions and not suddenly stop taking the medication at any stage during treatment.

Discontinuation should only be done through the advice of a medical doctor recommending the treatment. It is more than likely that your doctor will ease your system off the medication in a gradual discontinuation process (tapering), reducing the risk of severe withdrawal side-effects.

Discontinuation syndrome may be alarming to experience as symptoms can often mimic those of a mental illness. It is strongly advised not to discontinue the medication treatment on your own (out of fear) for this reason too, especially if the drug was prescribed for major depressive symptoms. During discontinuation, your doctor will want to monitor symptoms to determine those associated with withdrawal, as well as perhaps those linked to the original medical condition undergoing treatment.

Your doctor will closely monitor and guide you through your treatment on this medication. If at any stage, you feel uncomfortable or concerned, consult your doctor for advice and guidance.

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