Psychotic disorders are some of the best known and most striking for most of the population, schizophrenia being the best known disorder of this type. Research on these problems has generated different pharmacological treatments to reduce and keep the symptoms of those who suffer from it under control. One of these drugs, relatively recent, is paliperidone .

However, despite the usefulness of antipsychotics, not all patients can or want to take medication orally, or find it cumbersome to take every few months. This is why depot presentations have been devised, one example being paliperidone palmitate .

Paliperidone and paliperidone palmitate: drug type

Paliperidone palmitate is a type of presentation of paliperidone, an atypical or second generation antipsychotic which in turn is the active metabolite of another antipsychotic, risperidone. Paliperidone is a relatively new drug that is highly effective in the treatment of psychotic symptoms such as those of schizophrenia and schizoaffective disorder, reducing the likelihood of symptoms such as hallucinations, aggression or disorganised behaviour.

With regard to paliperidone palmitate itself, this is a medication that is administered intramuscularly, by injection . In this type of presentation or administration of the drug, a crystallised form of , which will be slowly released into the blood over time, is injected into the muscle without the subject having to take any tablets (this is a depot presentation of prolonged release). This is especially useful for subjects with memory problems, who find it difficult to schedule pills, or who are reluctant to take medication.

Usually a monthly or even quarterly injection is performed (although this may vary according to the medical centre and the patient’s symptoms), which must be carried out by a doctor or competent health professional . In any case, if oral administration is desired, paliperidone can also be used.

Mechanism of action

Once injected, the paliperidone palmitate will gradually hydrolyse and transform into paliperidone in the body, as the drug is released into the bloodstream.

Paliperidone and paliperidone palmitate are drugs classified as atypical antipsychotics. Their therapeutic action is due to their effects in blocking dopamine D2 receptors and serotonin 5-HT2.

The antidopaminergic action at a mesolimbic level reduces hallucinations and maintains the levels of this hormone so that they do not occur, while the effect on serotonin makes it difficult for the reduction of dopamine to greatly affect other brain areas such as the cortex. It also has a mild antagonistic effect on alpha-adrenergic receptors and on histaminergics, resulting in some of the drug’s possible side effects.

Uses in treatment of disorders

The main indication for paliperidone palmitate is the treatment of symptoms of psychotic disorders , specifically schizophrenia. However, unlike other antipsychotics, paliperidone palmitate is not generally used as a treatment for acute psychotic breaks, but as a maintenance psychopharmaceutical.

That is, for the treatment of an acute psychotic break, the patient would first be stabilized with other drugs (e.g. paliperidone) and then paliperidone palmitate would be planned to keep the symptoms under control and prevent further outbreaks.

The exception is found in those cases that even without being stabilized have already shown a positive response to paliperidone or risperidone and the psychotic symptoms are mild or moderate. This drug has been approved by the FDA for the treatment of schizophrenia from the age of twelve .

In addition to schizophrenia, paliperidone palmitate has been shown to be effective in schizoaffective disorder or other problems, being possible to use it as an adjuvant treatment to antidepressant medication (although it has to be something prescribed by the doctor, since it depends on which medication can interact in a dangerous way for the health).

Side effects and contraindications

Although paliperidone palmitate is a useful and effective formulation in the maintenance treatment of schizophrenia and has multiple advantages, it can lead to more or less undesirable side effects and may even be contraindicated in some people.

Some side effects that may appear after administration are the presence of drowsiness, difficulty in urination and brownish or dark-coloured urine , headaches, chills, increased hunger and thirst, weight gain, cold symptoms, visual disturbances, tremors, allergic reactions or inflammation in the area where the injection was made. More severe symptoms may include arrhythmias or tachycardia, hyperglycemia, seizures or hypotension.

Although as an atypical antipsychotic its effect on serotonin reduces the effects on dopamine in the cortex and the tuberoinfundibular dopamine pathway, it has been observed that its administration can generate alterations and difficulties in sexuality related to an increase in prolactin, such as a decrease in libido or priapism in men.

As we have mentioned , some people are contraindicated to this drug , and should not be treated with it or have to assess its suitability with the doctor. Among them we can find patients with cardiac or cardiovascular, renal, stomach or liver problems.

Neither do people with diabetes mellitus (since it can generate alterations in blood sugar levels), subjects with dementia (it increases the risk of death during treatment), pregnant women and nursing mothers. Likewise, it should not be mixed with other medications since may generate interactions between drugs such as lithium salts, levodopa, alcohol , antibiotics and other psychopharmaceuticals.

Bibliographic references:

  • Nussbaum, A.M. & Stroup, T.S. (2012). Paliperidone palmitate for schizophrenia. Cochrane Database of Systematic Reviews, 6. DOI: 10.1002/14651858.CD008296.pub2.