Within its structure, paroxetine has two chiral centers that give rise to four different stereoisomers. Only the (3S, 4R) - (-) enantiomer is marketed.
Paroxetine has a "high affinity for the serotonin reuptake transporter (SERT) and is much more potent and selective than fluoxetine (another SSRI antidepressant).
Like all drugs belonging to the SSRI class, paroxetine is also preferred over tricyclic antidepressants (TCAs) due to its better tolerability and reduced side effects compared to the latter.
Paroxetine is available in many medicines which can be in the form of tablets, oral drops or oral suspension. These medicines, in order to be dispensed, require a repeatable medical prescription (RR). However, they are classified as prescription drugs. band A, their cost can be reimbursed by the National Health System (SSN), wholly or partially, depending on the case (it may be necessary to pay a ticket).
Examples of Medicines containing Paroxetine
- Dapagut®
- Daparox®
- Dropaxin®
- Eutimil®
- Paroxetina DOC®
- Paroxetine EG®
- Paroxetine Mylan®
- Serestill®
- Sereupin®
- Seroxat®
- Stiliden®
Paroxetine should not be used in patients under 18 years of age. However, in case the doctor deems it absolutely necessary, he could also prescribe paroxetine for this category of patients. It is important to know that the use of paroxetine by these patients may increase the risk of developing suicidal thoughts, suicide attempts and hostility.
When patients enter a manic phase, treatment with paroxetine should be discontinued.
In addition to what has been said so far, it is important to know that:
- Caution should be exercised when administering paroxetine to patients with pre-existing liver and / or kidney disease, especially if severe.
- Attention should be paid to the administration of paroxetine in patients with previous heart disease.
- Since paroxetine can alter blood glucose levels, an adjustment in the dose of insulin and / or antidiabetic drugs given may be necessary in diabetic patients.
- Since paroxetine can cause seizures, care should be taken when administering the drug to patients with epilepsy.
- Great caution should be exercised when administering paroxetine to patients treated with electroconvulsant therapy (TEC).
- Paroxetine may cause an increase in internal ocular pressure, so care should be taken when administering the drug to patients with glaucoma.
- Paroxetine can increase the risk of bleeding, so if you experience any abnormal bleeding, you should tell your doctor right away.
- A physician should be consulted before stopping treatment with paroxetine, as abrupt discontinuation of therapy may lead to withdrawal symptoms.
Please note
Paroxetine may cause side effects that affect the ability to drive or use machines, so caution should be used.
, their association, therefore, should be avoided:
- Other SSRIs, such as fluoxetine, sertraline and fluvoxamine;
- MAOIs (monoamine oxidase inhibitors), such as moclobemide;
- Tryptophan;
- Triptans (drugs used in the treatment of migraine), such as - for example - sumatriptan and almotriptan;
- Tramadol, an opioid analgesic;
- Linezolid, an antibiotic;
- Methylene blue, a preoperative highlighting agent;
- Lithium, a drug used in the treatment of bipolar disorders;
- Fentanyl, an opioid pain reliever;
- Preparations based on hypericum (or St. John's wort), a plant with known antidepressant properties.
Paroxetine can cause an increase in the blood levels of pimozide (a drug used to treat psychosis), therefore, concomitant use of these two drugs should be avoided.
Since paroxetine is metabolised by hepatic enzymes, caution should be exercised in concomitant administration of drugs capable of inhibiting these enzymes.
Paroxetine can interact with some drugs used to treat AIDS, such as - for example - ritonavir.
In addition, paroxetine may enhance the efficacy - and at the same time the side effects - of the following drugs:
- Procyclidine (a drug used to relieve the symptoms of Parkinson's disease);
- Tricyclic antidepressants, such as imipramine and clomipramine;
- Antipsychotic drugs, such as perphenazine, thioridazine, and risperidone;
- Medicines to treat children with ADHD (attention deficit hyperactivity disorder), such as atomoxetine;
- Antiarrhythmics, such as flecainide;
- Metoprolol, a drug used to treat angina pectoris and hypertension;
- Phenothiazines, a group of molecules with antipsychotic and antihistamine action;
- Anticoagulant drugs, such as - for example - acenocoumarol.
Paroxetine can interact with tamoxifen, an anticancer drug used to treat breast cancer.
Finally, great caution should be exercised when administering paroxetine to patients taking drugs that increase the risk of bleeding, including:
- Phenothiazines, such as - for example - chlorpromazine;
- Clozapine, a drug used in the treatment of schizophrenia;
- Tricyclic antidepressants;
- Acetylsalicylic acid;
- NSAIDs (non-steroidal anti-inflammatory drugs), such as - for example - ibuprofen or celecoxib.
In any case, it is advisable to inform your doctor if you are taking - or have recently been taken - other drugs or products of any kind, even if they are not listed in the above lists.
Paroxetine with Alcohol
The concomitant intake of paroxetine and alcohol should be avoided.
of the medicine containing paroxetine that you are taking.
Disorders of the blood and lymphatic system
Treatment with paroxetine can cause disturbances in the system responsible for producing blood cells (blood and lymphatic system). These disorders can lead to thrombocytopenia, which is a reduced concentration of platelets in the bloodstream. This reduction increases the risk of bruising, abnormal bleeding and / or haemorrhage.
Allergic reactions
Paroxetine can trigger allergic reactions in sensitive individuals. These reactions can manifest themselves in the form of hives or itching. Or, swelling of the throat, tongue or skin may occur resulting in difficulty breathing and / or itching.
Endocrine pathologies
Paroxetine therapy can cause the syndrome of inappropriate antidiuretic hormone secretion (SIADH) which - in turn - could lead to the onset of water retention and hyponatremia (lowering of blood sodium levels).
Metabolism and nutrition disorders
Paroxetine can cause an increase in blood cholesterol levels and a reduction in appetite. The drug can also promote hyponatremia, especially in older patients.
Psychiatric disorders
Treatment with paroxetine can cause various psychiatric disorders, including:
- Drowsiness;
- Agitation;
- Insomnia;
- Abnormal dreams and nightmares
- Confusion;
- Hallucinations;
- Manic periods;
- Anxiety;
- Panic attacks;
- Depersonalization;
- Restlessness;
- Akathisia, that is, inability to sit or stand still;
- Self-harming and / or suicidal thoughts or behaviors.
Disorders of the nervous system
Among the disorders of the nervous system that can be induced by paroxetine therapy, we remember:
- Difficulty concentrating
- Dizziness
- Tremors
- Headache
- Extrapyramidal disorders, i.e. Parkinson-like symptoms;
- Seizures or fits
- Restless Legs Syndrome.
Eye disorders
Paroxetine can cause blurred vision and mydriasis (pupil dilation). In addition, the drug can also cause a sudden increase in intraocular pressure (acute glaucoma).
Ear disorders
Treatment with paroxetine can give rise to tinnitus, i.e. an auditory disorder characterized by the perception of noises such as buzzing, rustling, hissing, whistling, rattling, etc.
Cardiovascular pathologies
In the heart, paroxetine can cause sinus tachycardia or bradycardia.
On the vascular level, however, the drug can cause transient increases or decreases in blood pressure.
Gastrointestinal disorders
Nausea, vomiting, diarrhea or constipation and dry mouth may occur after taking paroxetine. Gastrointestinal bleeding may also occur.
Hepatobiliary disorders
Treatment with paroxetine can cause an increase in blood levels of liver enzymes. In addition, the drug could promote the onset of hepatitis, sometimes associated with jaundice and / or liver failure.
Skin and skin tissue disorders
Paroxetine can cause increased sweating, skin rash, itching and photosensitivity reactions. More severe skin reactions may also occur, such as Stevens-Johnson syndrome (a variant of polymorphic erythema) and toxic epidermal necrolysis.
Renal and urinary disorders
Paroxetine therapy can cause urinary retention and incontinence.
Diseases of the reproductive system and breast
Treatment with paroxetine can cause sexual dysfunction, such as decreased libido, ejaculation problems, male impotence and inability to reach orgasm. In addition, paroxetine can induce hyperprolactinaemia (ie an increase in blood levels of the hormone prolactin) which can lead to abnormal milk secretion (galactorrhea) in both women and men.
Finally, the drug can induce priapism, which is a "long and painful erection not accompanied by sexual arousal."
Bone fractures
An increased risk of bone fractures has been observed in patients taking paroxetine - or other medicines of this type.
Other side effects
Other side effects that may occur following the intake of paroxetine are:
- Frequent yawning
- Weight gain
- Myalgia and / or arthralgia;
- Tiredness;
- Asthenia;
- Peripheral edema.
Serotonin syndrome
This syndrome can occur especially if paroxetine is administered concomitantly with drugs that are also capable of increasing serotonergic transmission. It is also defined as serotonin poisoning and is caused by an excess of serotonergic activity in the central nervous system. Serotonin poisoning can occur in mild, moderate or severe forms.
Symptoms that can arise are:
- Tachycardia;
- Chills;
- Increased sweating;
- Headache
- Mydriasis (dilation of the pupils);
- Tremors
- Myoclonia (short and involuntary contraction of a muscle or group of muscles);
- Spasms
- Accentuated reflections.
- Accentuation of intestinal noises (borborygmi);
- Diarrhea;
- Hypertension;
- Fever.
The patient can also go into a state of shock with body temperatures exceeding 40 ° C.
In addition, rhabdomyolysis (breakdown of skeletal muscle cells and release of substances present within the musculature into the bloodstream), convulsions and kidney failure can occur.
Withdrawal symptoms: what they are and how long they last
If paroxetine treatment is stopped abruptly, so-called withdrawal symptoms may occur. Such symptoms are:
- Dizziness
- Sensory disturbances;
- Sleep disorders;
- Anxiety;
- Headache
- Agitation;
- Sweating;
- Tremor;
- Nausea;
- Confusion;
- Emotional instability;
- Palpitations;
- Visual disturbances;
- Diarrhea;
- Irritability.
These symptoms are usually self-limiting, but you should still consult your doctor before stopping paroxetine therapy.
Paroxetine overdose
In the event of a paroxetine overdose, you should immediately contact a doctor or go to the nearest hospital. Symptoms that may occur following an overdose of the drug are:
- He retched;
- Mydriasis;
- Headache
- Fever;
- Changes in blood pressure
- Anxiety;
- Agitation;
- Tachycardia;
- Tremor.
Paroxetine is a potent inhibitor of SERT and - by binding to it instead of serotonin - causes it to remain inside the synaptic wall for a prolonged time, thus allowing it to continue interacting with its own postsynaptic receptors. The enhancement of serotonergic transmission. induced in this way, it allows the improvement of the psychiatric pathologies treated.
in the form of tablets, oral drops or oral suspension.
The drug should preferably be taken in the morning on a full stomach. The tablets should be swallowed whole and NOT chewed, while the oral drops should be diluted in water.
The dosage of paroxetine must be established by the physician on an individual basis according to the pathology to be treated and the patient's condition.
In case of impaired hepatic and / or renal function, an adjustment of the administered dose may be necessary.
The doses of paroxetine usually used are shown below. However, follow the directions given by your doctor and the instructions contained in the package insert of the paroxetine-based medicine you are taking.
Major depressive episodes
The usual starting dose of paroxetine is 20 mg of the drug, to be taken once daily. The dose can be gradually increased up to a maximum of 50 mg of active ingredient.
Obsessive Compulsive Disorder
The drug dose initially administered is 20 mg of drug per day which can be increased to 40 mg per day, to be administered in divided doses. The doctor may increase the dosage - in case of inadequate response - up to a maximum of 60 mg of paroxetine per day.
Panic disorder, with or without agoraphobia
The usual starting dose of paroxetine is 10 mg per day. Thereafter, the amount of the drug is increased up to 40 mg, to be administered in two divided doses.
In case of an inadequate response from the patient, the doctor may decide to gradually increase the dose up to a maximum of 60 mg of paroxetine per day.
Social anxiety disorder / social phobia, generalized anxiety disorder and post-traumatic stress disorder
The recommended dose of paroxetine is 20 mg per day. In case of inadequate response, the doctor may decide to gradually increase the dose up to a maximum of 50 mg of active ingredient per day.
Use in the elderly
The doses of paroxetine usually used are the same as those used for adult patients, but the maximum daily dose should not exceed 40 mg per day.
.In addition - when drugs such as paroxetine are taken in the last trimester of pregnancy - it may increase the risk of persistent pulmonary hypertension of the newborn (PPHN) which occurs with an increase in breathing rate and a bluish skin. In addition, symptoms such as: difficulty falling asleep or feeding, difficulty breathing, cyanosis, unstable body temperature, vomiting, constant crying, muscle stiffness or weakness, lethargy, tremors, nervousness or seizures may occur in the newborn. Usually, these symptoms begin within 24 hours of birth.
Paroxetine - albeit in minimal quantities - is excreted in breast milk.
For all the reasons mentioned above, pregnant women or mothers who are breastfeeding must absolutely seek advice from their doctor before taking paroxetine and carefully evaluate with him the relationship between the expected benefits for the mother and the risks to the baby that would result. from its use.
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