pheniramine

Action and Spectrum

Actions and Spectrum: 

• Histamine Receptor Blockade: pheniramine works by competitively blocking the H1 receptors, which are histamine receptors found on various cells, including those in the respiratory system, blood vessels, and skin. 
• Inhibition of Histamine Effects: By blocking these receptors, pheniramine prevents histamine from binding and exerting its effects. Histamine is involved in the inflammatory response, causing symptoms such as itching, sneezing, runny nose, and watery eyes. 

pheniramine is primarily used to relieve symptoms associated with allergic conditions, including: 

• Allergic rhinitis (hay fever): It helps alleviate symptoms such as sneezing, runny nose, and itching. 
• Allergic conjunctivitis: pheniramine can reduce redness, itching, and watering of the eyes. 
• Dermatographism: It may be used to relieve skin itching and hives associated with allergic reactions. 
• Pruritus: pheniramine may also be used to alleviate itching caused by various skin conditions. 

Drug Interaction

Adverse Reaction

Frequency not defined 

Dizziness 

Inability to concentrate 

Irritability 

Nausea 

Diarrhea 

Sedation 

Tinnitus 

Incoordination 

Insomnia and tremors 

Vomiting 

Epigastric pain 

Dryness of mouth 

Colic 

Anorexia 

Constipation 

Black Box Warning

Black box warning: 

None 

Contraindication / Caution

Contraindications/caution: 

Contraindications: 

• Hypersensitivity or Allergy: pheniramine should not be used in individuals who have a known hypersensitivity or allergy to pheniramine or any of its components. 
• Newborns and Premature Infants: The use of pheniramine is generally contraindicated in newborns and premature infants due to their increased susceptibility to the sedative effects of antihistamines. 
• Closed-Angle Glaucoma: pheniramine may increase intraocular pressure and is contraindicated in individuals with closed-angle glaucoma. 
• Urinary Retention or Obstruction: Antihistamines, including pheniramine, can cause urinary retention. They should be used with caution or avoided in individuals with prostatic hypertrophy, bladder neck obstruction, or other urinary retention issues. 

Caution: 

• Central Nervous System (CNS) Depression: pheniramine has sedative properties and can cause drowsiness. Caution is advised when performing activities that require mental alertness, such as driving or operating heavy machinery. 
• Anticholinergic Effects: pheniramine has anticholinergic properties, which can lead to side effects such as dry mouth, blurred vision, and constipation. Individuals who are prone to these effects or have pre-existing conditions should use pheniramine with caution. 
• Geriatric Population: Elderly individuals may be more sensitive to the sedative effects of pheniramine. Caution is advised, and dosage adjustments may be necessary. 
• Renal Impairment: Individuals with renal impairment may experience altered excretion kinetics of pheniramine. Dose adjustments may be necessary, and caution is advised. 
• Hepatic Impairment: pheniramine undergoes hepatic metabolism, and individuals with severe liver disease may experience altered metabolism.

Pregnancy / Lactation

Pregnancy consideration: 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.    

Pregnancy Category: C 

Lactation: Excretion of the drug in human breast milk is known 

Pregnancy category: 

• Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester. 
• Category B: there was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women. 
• 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: 

pheniramine exerts its effects by blocking histamine receptors, specifically H1 receptors. Histamine is a natural substance released by the body during allergic reactions, contributing to symptoms such as itching, sneezing, runny nose, and watery eyes. 

• Histamine Antagonism: By blocking H1 receptors, pheniramine inhibits the effects of histamine, thereby reducing or preventing allergic symptoms. 
• CNS Penetration: pheniramine readily crosses the blood-brain barrier, leading to central nervous system (CNS) effects. 
• Sedative Properties: pheniramine has sedative properties and may cause drowsiness. This sedative effect is more pronounced in comparison to second-generation antihistamines, which are less likely to cause sedation. 

Pharmacokinetics: 

Absorption 

pheniramine is commonly administered orally, and it is well-absorbed from the gastrointestinal tract. After oral administration, pheniramine is rapidly absorbed, leading to a relatively quick onset of action. 

Distribution 

pheniramine binds extensively to plasma proteins, mainly albumin. It is distributed throughout the body, including the central nervous system, due to its ability to cross the blood-brain barrier. 

Metabolism 

pheniramine undergoes hepatic metabolism, primarily through the cytochrome P450 enzyme system, particularly CYP2D6. The metabolites formed during metabolism are less pharmacologically active than the parent compound. 

Elimination and Excretion 

pheniramine and its metabolites are primarily excreted in the urine. The elimination half-life of pheniramine is relatively short, contributing to its need for multiple doses throughout the day. 

Adminstartion

Administration: 

Oral administration 

pheniramine is commonly available in oral formulations, including tablets and syrups. It is often administered multiple times a day, especially for the relief of allergy symptoms. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: pheniramine 

Why do we use pheniramine? 

pheniramine is an antihistamine medication that is commonly Pheniramine is a type of antihistamine that is frequently prescribed to treat allergic responses. It is classified as a first-generation antihistamine which is used to relieve symptoms associated with allergic reactions.  

• Allergic rhinitis: pheniramine is a medication used to treat allergic rhinitis, also known as hay fever. Symptoms may include sneezing, runny nose, itching, and nasal congestion. 
• Allergic Conjunctivitis: It is used to relieve symptoms of allergic conjunctivitis, such as redness, itching, and watering of the eyes. 
• Dermatographism: pheniramine may be used to alleviate itching and hives associated with dermatographism, a condition where the skin becomes raised and inflamed when scratched. 
• Pruritus (Itching): pheniramine is effective in relieving itching associated with various skin conditions, including eczema and insect bites. 
• Histamine-Mediated Allergic Reactions: It is used to counteract the effects of histamine in the body during allergic reactions, helping to reduce symptoms such as itching, swelling, and nasal congestion. 
• Cold and Allergy Relief: pheniramine may be included in over-the-counter cold and allergy medications, often in combination with decongestants and analgesics, to provide relief from multiple symptoms. 
• Motion Sickness: In some cases, pheniramine’s sedative properties may be utilized to alleviate symptoms of motion sickness. 
• Sedation: Due to its sedative effects, pheniramine may be used in certain over-the-counter sleep aids or nighttime cold and flu medications to promote sleep.