dimethindene

Action and Spectrum

Actions and Spectrum: 

dimethindene is an antihistamine drug primarily used to relieve allergy symptoms and treat conditions such as allergic rhinitis (hay fever) and allergic skin reactions. It is available in various forms, including oral tablets, drops, and topical creams or gels.  

• Antihistamine Action: dimethindene primarily works by blocking the effects of histamine. Histamine is responsible for various symptoms of allergies, including sneezing, itching, runny nose, and watery eyes. By blocking histamine receptors, dimethindene helps alleviate these symptoms. 
• Anti-Allergic Effects: dimethindene is effective in relieving the symptoms associated with allergic reactions, like itching and swelling of the skin, as well as nasal congestion and sneezing. 
• Mild Sedative Effect: dimethindene is classified as a first-generation antihistamine. Unlike newer, second-generation antihistamines, it can have a sedative (drowsiness-inducing) effect on some individuals. This soothing effect can be beneficial in some instances, such as when the drug treats allergies that interfere with sleep. However, it can also cause drowsiness and impair cognitive function, so it should be used cautiously, especially when driving or operating heavy machinery. 
• Duration of Action: dimethindene’s duration of action is relatively short compared to other antihistamines. It typically needs to be taken multiple times daily to maintain its effectiveness in controlling allergy symptoms. 
• Topical Use: dimethindene is also available in topical formulations (creams or gels) that can be applied directly to the skin to relieve itching and inflammation caused by allergic reactions or insect bites. 
• Limited Use: dimethindene is generally considered less preferred for long-term use due to its soothing effects and the availability of newer antihistamines with a better side-effect profile.

Drug Interaction

Adverse Reaction

Frequency not defined 

Dryness of mouth 

Tachycardia and arrhythmias 

Blurring of vision 

Urinary retention 

CNS depression 

GI upsets 

Paradoxical CNS excitation 

Constipation 

Blood dyscrasias 

Thickened resp mucus 

Black Box Warning

Black Box Warning: 

None 

Contraindication / Caution

Contraindication/Caution: 

Contraindication 

• Hypersensitivity or Allergy: Individuals with known hypersensitivity or allergy to dimethindene or its components should not use this medication. 
• Narrow-Angle Glaucoma: dimethindene can cause an increase in intraocular pressure, which may worsen narrow-angle glaucoma. It should be avoided in individuals with this condition unless an ophthalmologist advises it. 
• Prostate Hypertrophy: dimethindene may exacerbate benign prostatic hypertrophy (enlarged prostate) symptoms. It can lead to urinary retention and worsen symptoms in individuals with this condition. 
• Bladder Neck Obstruction: Like prostate hypertrophy, dimethindene can cause or worsen urinary retention and bladder neck obstruction. It should be avoided in individuals with such obstructions. 
• Gastrointestinal Obstruction: dimethindene can have anticholinergic effects, which may slow down gastrointestinal motility. It is contraindicated in individuals with gastrointestinal obstruction. 
• Epilepsy: Antihistamines like dimethindene can lower the seizure threshold and might increase the risk of seizures in individuals with epilepsy. It should be used cautiously, if at all, in individuals with a history of seizures or epilepsy. 
• Severe Liver Disease: dimethindene is metabolized by the liver, and its clearance may be impaired in individuals with severe liver disease. It should be used with caution or avoided in these cases. 
• Pregnancy and Breastfeeding: The safety of dimethindene during pregnancy and breastfeeding is not well established. It should be used only when the potential benefits outweigh the potential risks and under the guidance of a healthcare provider. 
• Children Under 1 Year: dimethindene is generally not recommended for use in infants under one year, as its safety and efficacy in this age group may not be well-established. 
• Alcohol and Sedative Use: dimethindene can enhance the sedative effects of alcohol and other CNS (central nervous system) depressants.  

Caution 

• Sedation: dimethindene is a first-generation antihistamine and can have a soothing effect on some individuals. This drowsiness can impair your ability to drive or operate heavy machinery.  
• Alcohol and CNS Depressants: dimethindene can enhance the sedative effects of alcohol and other CNS (central nervous system) depressants, such as sedative medications, tranquilizers, or sleep aids. Avoid alcohol and other sedative substances while taking dimethindene. 
• Drowsiness: Be aware that dimethindene may cause drowsiness, and this effect can be more pronounced when used in combination with other medications that have sedative properties. 
• Elderly Individuals: The sedative effects of dimethindene can be more pronounced in older adults. Use caution when prescribing or taking this medication in elderly individuals, as it may increase the risk of falls or accidents. 
• Children: dimethindene may not be suitable for all children, especially those under one year of age. Consult with a healthcare provider before giving dimethindene to children, and follow the dosing instructions carefully. 
• Pregnancy and Breastfeeding: The safety of dimethindene during pregnancy and breastfeeding is not well established. If pregnant condition or breastfeeding, consult your healthcare provider before using dimethindene to weigh the potential benefits against the potential risks. 
• Underlying Medical Conditions: Inform your healthcare provider of any underlying medical conditions you have, such as epilepsy, glaucoma, liver disease, or urinary problems. dimethindene may not be suitable for individuals with certain medical conditions, and your healthcare provider can assess whether it is safe for you. 
• Interactions with Other Medications: dimethindene may interact with other medications you are taking. Inform your healthcare provider about all prescription, over-the-counter, and herbal products. 
• Driving and Operating Machinery: dimethindene’s sedative effects can impair your ability to drive safely/operate heavy machinery. Avoid these activities until you are sure about how the medication affects you. 
• Duration of Use: dimethindene is typically used for short-term relief of allergy symptoms. Prolonged use or misuse of antihistamines can lead to reduced effectiveness and potential side effects. Follow your healthcare provider’s guidance on the duration of treatment. 

Pregnancy / Lactation

Pregnancy consideration:  

US FDA pregnancy category: Not assigned. 

Lactation:   

Excreted into human milk: Not known. 

Pregnancy category: 

• Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester. 
• <b>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: 

dimethindene is a first-generation antihistamine with pharmacological properties primarily antagonizing histamine H1 receptors. By binding to these receptors, dimethindene competitively inhibits the actions of histamine, thereby mitigating various allergic responses such as itching, sneezing, rhinorrhea, and ocular symptoms.

Additionally, dimethindene possesses mild anticholinergic properties, which contribute to its soothing effect and can reduce gastrointestinal motility. These properties make dimethindene effective in relieving allergy symptoms, but its soothing potential may limit its use in situations where alertness is critical. The medication is available in multiple forms, including oral tablets, drops, and topical preparations, allowing for flexibility in its administration based on the specific clinical indication. 

Pharmacodynamics: 

Mechanism of action: dimethindene is an antihistamine medication, and its mechanism of action primarily revolves around its ability to blocks the effects of histamine, a naturally occurring chemical in the body that plays a crucial role in allergic reactions and other physiological processes.  

• Histamine Receptor Blockade: dimethindene is an antagonist of histamine H1 receptors. Histamine H1 receptors are found on various cells throughout the body, including those in the respiratory tract, blood vessels, and skin. When histamine binds to these receptors, it triggers a series of responses that lead to allergy symptoms, such as itching, sneezing, nasal congestion, and skin reactions. 
• Competitive Binding: dimethindene competes with histamine for binding to the H1 receptors. By binding to these receptors, dimethindene prevents histamine from attaching to and activating them. This competitive binding inhibits the actions of histamine, effectively blocking or reducing the allergic responses triggered by histamine. 
• Symptom Relief: As dimethindene blocks H1 receptors, it helps alleviate the symptoms associated with histamine release, such as itching, sneezing, runny nose, and watery eyes. Additionally, when used topically in cream or gel form, dimethindene can relieve skin itching and inflammation caused by allergic reactions, insect bites, or contact dermatitis. 
• Sedative Effect: dimethindene is a first-generation antihistamine, and it has a soothing effect on some individuals because of its ability to cross the BBB (blood-brain barrier) and interact with central nervous system receptors. This sedative property can contribute to drowsiness, which may be desirable in some situations, such as nighttime use for allergy relief, but can also lead to side effects like sleepiness and impaired alertness. 

Pharmacokinetics: 

Absorption 

dimethindene can be absorbed through various routes, depending on the formulation. It is absorbed from the gastrointestinal tract when taken orally (e.g., in tablet or liquid form). The absorption rate may vary between individuals but is relatively rapid. 

Distribution 

dimethindene is distributed throughout the body via the bloodstream. It can cross the blood-brain barrier, contributing to its potential sedative effects. The drug binds to plasma proteins to some extent but can also penetrate tissues and organs, including the central nervous system and skin. 

Metabolism 

dimethindene undergoes hepatic (liver) metabolism primarily through the cytochrome P450 enzyme system. The exact metabolic pathways and metabolites of dimethindene may vary among individuals. This metabolism may lead to the formation of various metabolites, some of which may still retain pharmacological activity. The dimethindene metabolism can influence its action duration and potential side effects. 

Elimination and Excretion 

The elimination of dimethindene and its metabolites occurs primarily through the renal (kidney) route. This means that the drug and its byproducts are filtered out of the bloodstream by the kidneys and then excreted in the urine. The elimination rate can vary among individuals and may be influenced by factors such as renal function and other medications being taken concurrently. 

Adminstartion

Administration: 

dimethindene is available in various forms, including oral tablets, drops, and topical creams or gels. The specific administration instructions for dimethindene can vary depending on the formulation and the individual’s age.  

Oral Tablets: 

Follow the dosing instructions which is provided by the healthcare professional or those printed on the product label. 

Swallow the tablet whole with a full glass of water unless otherwise directed. 

You may take dimethindene with/without food, but taking it with food may help diminish stomach upset in some individuals. 

Oral Drops: 

Measure the prescribed dose using the provided dropper or dosing syringe. 

Dilute the drops in a small amount of water or juice if instructed. 

Administer the drops directly into the mouth/mix them with a small amount of liquid, as directed by your healthcare provider. 

Be sure to use the appropriate dosage for the individual’s age and weight, as a healthcare professional recommends. 

Topical Cream or Gel: 

Wash your hands before and after applying the cream or gel. 

Apply a thin layer of cream/gel to the affected skin area. 

Gently massage or rub the product into the skin until it is absorbed. 

Follow the specific instructions provided with the topical product regarding frequency and duration of application. 

Duration of Treatment: 

Follow your healthcare provider’s recommendations regarding the duration of dimethindene treatment. Typically, it is used for short-term relief of allergy symptoms or allergic skin reactions. 

Do not use dimethindene for an extended period or at a higher dose than prescribed without consulting a healthcare professional. 

Special Populations: 

Children: Follow the dosing instructions for children according to their age and weight. dimethindene may be available in different strengths for pediatric use, so be sure to use the correct product. 

Elderly: Use caution and follow the dosing instructions for older adults, as they may be more sensitive to the sedative effects of dimethindene. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: dimethindene 

Why do we use dimethindene? 

dimethindene is an antihistamine medication used to treat allergy symptoms and allergic reactions. It works by blocking the effects of histamine, a chemical the body releases in response to allergens.  

• Allergic Rhinitis (Hay Fever): dimethindene can help relieve symptoms of allergic rhinitis, including sneezing, runny or itchy nose, itchy or watery eyes, and nasal congestion. 
• Allergic Conjunctivitis: It is used to treat allergic conjunctivitis, which is inflammation of the eye’s conjunctiva. 
• Urticaria (Hives): dimethindene can relieve itching and redness associated with urticaria, commonly known as hives. Allergic reactions or other triggers often cause urticaria. 
• Allergic Skin Reactions: Topical formulations of dimethindene, such as creams or gels, can be applied directly to the skin to relieve itching and also inflammation caused by allergic reactions, insect bites, or contact dermatitis. 
• Pruritus (Itching): It may relieve itching associated with various skin conditions, including eczema and other dermatological disorders. 
• Insect Bites and Stings: dimethindene can help reduce itching and also discomfort caused by insect bites and stings. 
• Motion Sickness: In some cases, dimethindene may be used to alleviate symptoms of motion sickness, like nausea and dizziness. Its soothing properties can help with motion sickness, although other medications are more commonly used. 
• As a Sedative: Due to its sedative effects, dimethindene may induce drowsiness or sleep in certain situations, but it is not typically used.