pimethixene

Action and Spectrum

Actions and Spectrum: 

Action: 

Antihistamine: pimethixene exerts its primary action by blocking the effects of histamine, a chemical released during allergic reactions. It competes with histamine for binding to histamine receptors, thus reducing allergy symptoms, such as itching, sneezing, runny nose, and watery eyes. 

Anticholinergic: pimethixene also has anticholinergic properties, which means it can block the effects of acetylcholine, a neurotransmitter involved in various bodily functions. This can lead to drying of mucous membranes, relaxation of smooth muscles, and sedation. 

Spectrum: 

Allergic Conditions: pimethixene is used to alleviate symptoms of allergic reactions, such as hay fever, hives, and other skin allergies. It can help reduce itching, redness, and other discomfort associated with allergies. 

Drug Interaction

Adverse Reaction

Frequency not defined  

Constipation 

Headache 

CNS depression 

Drowsiness 

Blurred vision 

Increased gastric reflux 

Black Box Warning

Black Box Warning:  

None

Contraindication / Caution

Contraindication/Caution:  

Hypersensitivity or Allergy: pimethixene should not be used in individuals with a known hypersensitivity or allergy to the medication or its components. 

Severe Respiratory Conditions: pimethixene can suppress respiratory function and should be used cautiously or avoided in individuals with severe respiratory conditions like chronic obstructive pulmonary disease (COPD) or asthma. 

Alcohol and CNS Depressants: pimethixene has sedative effects and can cause CNS depression. It should not be used with alcohol or other CNS depressant medications due to the risk of increased sedation and respiratory depression. 

Children and Elderly: pimethixene is generally not recommended for use in children or elderly individuals due to increased sensitivity to its sedative and anticholinergic effects. 

Pregnancy and Breastfeeding: The safety of pimethixene during pregnancy and breastfeeding is not well established. It’s generally avoided in these situations unless the potential benefits outweigh the risks. 

Severe Liver or Kidney Impairment: pimethixene is metabolized in the liver and excreted by the kidneys. Individuals with severe liver or kidney impairment should use pimethixene cautiously and under medical supervision. 

Cardiovascular Conditions: pimethixene’s anticholinergic effects can increase heart rate and other cardiovascular effects. Individuals with certain cardiovascular conditions should use pimethixene cautiously. 

Pregnancy / Lactation

Pregnancy warnings:     

Pregnancy category: N/A 

Lactation: Excreted into human milk is unknown 

Pregnancy Categories:         

Category A: Studies that were well-controlled and met expectations revealed no risk to the fetus in either the first or second trimester. 

Category B: There were a lack of studies on pregnant women and no evidence of risk to the fetus in animal experiments.   

Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.    

Category D: adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.   

Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.    

Category N: There is no data available for the drug under this category

Pharmacology

Pharmacology:  

pimethixene is an antihistamine and anticholinergic drug primarily used to treat various allergic conditions and symptoms. 

Pharmacodynamics:  

Histamine H1 Receptor Antagonism: pimethixene exerts its primary therapeutic effect by blocking histamine H1 receptors. Chemical  histamine is pivotal for allergic responses., causing symptoms like itching, sneezing, and runny nose. Pimethixene reduces or prevents these allergic symptoms by antagonizing (blocking) H1 receptors. 

Pharmacokinetics: 

Absorption 

After oral administration, pimethixene is absorbed from the gastrointestinal tract into the bloodstream. The absorption rate and extent can be influenced by factors such as food intake and the formulation of the drug. 

Distribution 

Once absorbed, pimethixene is distributed throughout the body via the bloodstream. It can cross the blood-brain barrier, leading to its effects on the central nervous system.  

Metabolism 

pimethixene undergoes metabolism primarily in the liver. The exact metabolic pathways and enzymes involved may vary. The drug can be metabolized into several metabolites through oxidation, hydroxylation, and glucuronidation. The metabolites may have varying levels of pharmacological activity and contribute to the drug’s overall effects. 

Excretion and Elimination 

The metabolites of pimethixene are excreted from the body mainly through the renal route. The kidneys filter them and then eliminated in the urine. A small portion of the drug and its metabolites can also be excreted through the bile into the feces. 

Adminstartion

Administration:  

pimethixene is commonly available in oral tablet form. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: pimethixene 

Why do we use pimethixene?  

Allergic Reactions: pimethixene was used to relieve symptoms of allergic reactions by blocking the effects of histamine, a chemical released during allergic responses. 

Anxiety and Tension: pimethixene was occasionally prescribed to help manage mild anxiety and tension due to its sedative and calming effects. However, newer and more targeted medications have primarily replaced its use for anxiety. 

Insomnia: Its sedative properties made pimethixene useful for short-term management of insomnia, although again, other medications are generally preferred for this purpose now. 

Pruritus (Itching): pimethixene was sometimes used to relieve itching associated with various skin conditions or allergic reactions.