SNRIs

SNRIs Antidepressants (Serotonin-norepinephrine reuptake inhibitors

If you are taking antidepressants, make sure you have regular blood tests to check your potasium level and kidney and liver function.

Warning

 You should inform a family member or someone close to you if you start taking antidepressants. This is advised by manufacturers and the Royal Colleges and Department of Health - Please read the editorial in the medical journal Prescriber: This was compiled by Millie Kieve of APRIL and Janet Krska, Professor of Pharmacy

November 2015 editorial in Prescriber journal by Millie Kieve and Professor Janet Krska

Concensus Statement for Suicide Prevention from Department of Health and Royal Colleges

 The article explains the need for a family member or friend to be informed when antidepressants are prescribed: entitled The role of relatives and friends in antidepressant treatment:  

Tips that may help you if you feel depressed

These drugs are a class of antidepressant used in the treatment of clinical depression and other affective disorders. They are also sometimes used to treat anxiety disorders, obsessive-compulsive disorder, attention deficit hyperactivity disorder (ADHD) and chronic neuropathic pain. They have been promoted as acting upon two neurotransmitters in the brain that are said to play an important part in mood, namely, serotonin and norepinephrine.  The more widely-used selective serotonin reuptake inhibitors (SSRIs), are said to act only on serotonin. Some psychiatrists dispute this medical model of depression. See Dr Joanna Moncrieff's book under the BOOK heading in left menu.

List of SNRIs
- venlafaxine
(Effexor XR, Effexor) is the first and most commonly used SNRI. It is thought to works on dopamine somewhat at high dosages, but the majority of its effect is on serotonin and norepinephrine.
- desvenlafaxine (Pristiq) is the active metabolite of venlafaxine and is believed to work in the same manner.
- sibutramine (Meridia, Reductil) is an SNRI which failed to show antidepressant activity in animal tests, but instead has been widely marketed as an appetite suppressant drug for weight loss. (see press for ADR stories)
- nefazodone (Serzone) is an antidepressant with efficacy similar to SSRIs, but Promoted as not having the serious sexual side effects.   It has been discontinued in several countries due to some cases of liver failure. The tradename "Serzone" has been discontinued, however generic nefazodone is currently available. Blood test every 6 months to assess liver enzyme levels is necessary.
- milnacipran (Dalcipran/ Portugal; Ixel/ France) is promoted as beingf effective in the treatment of depression and Fibromyalgia syndrome (FMS). Although it has not been approved by the Food and Drug Administration for use in the United States, it has been commercially available in Europe and Asia for several years.
- desipramine (Norpramine, Pertofraneis) is technically a tricyclic antidepressant, and is usually categorized as such. Like an SNRI it is said to effect both serotonin and norepinephrine transporters. Because it also interacts with cholinergic and histamine receptors, it leads to the characteristic side effects associated with blockade of these receptors, it lacks the specificity that the serotonin norepinephrine specific reuptake inhibitors have.
- duloxetine (Cymbalta)see FDA recent warning below 
- bicifadine by DOV Pharmaceutical inhibits the reuptake of serotonin and norepinephrine (and dopamine to a lesser extent) but rather than being developed for the already crowded and criticised antidepressant market, it is being researched as a non-opioid, non-NSAID analgesic drug.

Psychiatric Adverse Drug Reactions
The reported side effects of taking SNRIs include gastrointestinal complaints such as dry mouth, nausea, and anorexia, somnolence (drowsiness), dizziness, abnormal dreams, sweating, sexual dysfunction, insomnia, tremor, nervousness and hypertension.

It is well documented that SNRIs can cause various sexual dysfunctions such as anorgasmia (inability to reach orgasm, most notably in women), diminished libido (sex drive) and erectile dysfunction or difficult/premature ejaculation in men. These side effects occasionally disappear spontaneously without discontinuing use of the drug, and in most cases resolve themselves after stopping taking the SNRI. (suddenly stopping the drug is not advisable).

Because one of the actions of the SNRIs is to block the reuptake of serotonin as the SSRIs do, it has many of the same side effects. The most common include nausea, drowsiness, headache, changes in appetite, vivid dreams, and sexual side effects.

Due to the effects of increased norepinephrine synaptic activity, these drugs are contraindicated in patients with hypertension, heart disease, or risk of stroke.

Withdrawing
As with the SSRIs, abrupt discontinuation of SNRI-medication usually leads to a discontinuation syndrome which could include states of anxiety, sleep disturbances (such as insomnia, vivid dreaming, fatigue, or mild pre-narcolepsy), other discomfort such as headaches, nausea lethargy, movement disorders (including trembling and difficulty walking), mood disorders (aggressive behavior, mania, irritability, crying spells, depression/suicidal thoughts) and sensory abnormalities (balance problems, vertigo, dizziness, light-headedness, parasthesia and shock-like sensations).

Due to the possibility of this condition, abruptly ceasing the medications is not recommended. The dosage should be tapered to avoid or lessen the chance of adverse reactions and further symptoms. For more information on withdrawing please click see menu on left 'Withdrawing from medicine'.

Reporting ADRs
If you have suffered a psychiatric adverse reaction to SNRIs please report. See left menu 'REPORTING ADRs'.

 SSRI stories in the press

 If you have or know of a case reported in the press concerning SSRI, SNRI and similar antidepressants please submit this to: http://www.ssristories.com/ 

 

Reporting Adverse Drug Reactions (ADRs)
If you have suffered psychiatric adverse reactions please report them. There may be side effects not mentioned on the data sheets. You can request a list of drugs used pre surgery and during surgery. You should be given patient information for all drugs prescribed as you are discharged from hospital.

Please report Adverse Drug Reactions (ADRs) to:

UK Yellow Card Reporting for Patient and Health Professional reports of Adverse Drug Reactions

USA and worldwide to the Food and Drug Administration for Patients and Healthcare Professionals

Universal free, independent drug safety website - Rxisk

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