From the Guidelines
Phenothiazines, such as chlorpromazine, are effective in treating schizophrenia and severe nausea and vomiting, but their use should be carefully considered due to potential side effects, as noted in studies 1. For schizophrenia, chlorpromazine typically starts at 25-100mg orally three times daily, gradually increasing to an effective dose range of 300-800mg daily divided into multiple doses, as dopamine receptor antagonists, they work by blocking D2 dopamine receptors in the mesolimbic pathway, reducing positive symptoms like hallucinations and delusions. Some key points to consider when using phenothiazines include:
- Side effects, such as extrapyramidal symptoms (parkinsonian features, akathisia), sedation, anticholinergic effects, orthostatic hypotension, and potentially tardive dyskinesia with long-term use, as mentioned in 1.
- The importance of regular monitoring for these effects, particularly in patients with a history of cardiovascular disease or those taking other medications that may interact with phenothiazines, as suggested in 1.
- The potential for phenothiazines to be used in combination with other medications, such as antiemetics, to enhance their effectiveness in treating nausea and vomiting, as noted in 1.
- The need for careful consideration of the potential benefits and risks of using phenothiazines in patients with specific symptom profiles or comorbidities, as discussed in 1.
Overall, while phenothiazines can be effective in treating schizophrenia and severe nausea and vomiting, their use should be carefully considered and monitored to minimize potential side effects and optimize treatment outcomes, as recommended in the most recent study 1.
From the FDA Drug Label
DOSAGE AND ADMINISTRATION–ADULTS ... Psychotic Disorders – Increase dosage gradually until symptoms are controlled Nausea and Vomiting– 10 mg to 25 mg q4 to 6h, p.r.n., increased, if necessary. The role of phenothiazines, such as chlorpromazine, is to treat schizophrenia and severe nausea and vomiting by increasing the dosage gradually until symptoms are controlled, with typical dosages ranging from 10 mg to 25 mg every 4 to 6 hours as needed for nausea and vomiting, and up to 200 mg daily or more for psychotic disorders 2.
- Key uses:
- Schizophrenia
- Severe nausea and vomiting
- Dosage:
- Schizophrenia: increase gradually until symptoms are controlled
- Nausea and vomiting: 10 mg to 25 mg every 4 to 6 hours as needed
From the Research
Role of Phenothiazines in Treating Schizophrenia
- Phenothiazines, such as chlorpromazine, have been used for decades to treat mental illnesses, including schizophrenia, mania in bipolar disorder, and psychosis 3.
- High potency phenothiazines, such as perphenazine, are used to treat various psychiatric conditions, including the positive symptoms of schizophrenia, symptoms of psychosis, and mania that can occur with bipolar disorder 3.
- Low/mid potency phenothiazines, such as chlorpromazine, are antipsychotic drugs that have been used to treat schizophrenia and schizophrenia-like disorders since the 1950s 3, 4.
Role of Phenothiazines in Treating Severe Nausea and Vomiting
- Phenothiazines offer relief for physical illnesses, including nausea and vomiting in both adults and children 3.
- Further research is needed to prove the efficacy of phenothiazines in treating physical symptoms, including severe nausea and vomiting 3.
Mechanism of Action and Biological Applications
- Phenothiazines are dopaminergic antagonists that inhibit D2 receptors with varying potency 3.
- These compounds are able to effectively inhibit dopamine, histamine, serotonin, acetylcholine, and α-adrenergic receptors, thus their effect and side-effect profiles are extremely diverse 5.
- Phenothiazines have a significant antimicrobial effect, and their antiviral, antiprotozoal, antifungal, and antiprion activities have also been described 5.
- They have also been proven to destroy cancer cells and sensitize them to chemotherapy, and might be applied as adjuvants in the treatment of infections and tumors in the future 5.