Afexa180 mg

Afexa 180 mg is a selective, non-sedating, second-generation H1 antihistamine indicated for the symptomatic relief of allergic conditions in adults and children. It effectively reduces histamine-mediated allergic symptoms without causing the drowsiness associated with older, first-generation antihistamines. Fexofenadine is clinically proven to improve health-related quality of life and work or school productivity in allergic patients.

Seasonal and Perennial Allergic Rhinitis

Afexa 180 mg is indicated for the relief of symptoms associated with seasonal allergic rhinitis (hay fever) and perennial allergic rhinitis (year-round nasal allergy) in adults and children 12 years of age and over. Symptoms effectively treated include:

• Sneezing — frequent, repetitive sneezing triggered by airborne allergens
• Rhinorrhea — runny nose with clear nasal discharge
• Nasal congestion — blocked or stuffy nose (partial symptomatic improvement)
• Itchy nose, palate, and throat — pruritus of the upper airway
• Lacrimation — increased tearing and watery eyes
• Itchy, red eyes (allergic conjunctivitis) — ocular pruritus and erythema associated with nasal allergy

Seasonal allergic rhinitis is typically triggered by outdoor allergens such as pollen from trees, grasses, and weeds during specific seasons. Perennial allergic rhinitis is caused by year-round indoor allergens such as house dust mites, pet dander, cockroach particles, and mold spores. Fexofenadine provides effective relief against both types.

Chronic Idiopathic Urticaria (Chronic Hives)

Afexa 180 mg is indicated for the relief of symptoms associated with chronic idiopathic urticaria (CIU) — also known as chronic spontaneous urticaria (CSU) — in adults and children 12 years of age and older. Fexofenadine has been shown in clinical trials to significantly reduce:

• The number and size of wheals (hives) — raised, itchy welts on the skin
• The severity of pruritus (itching) — one of the most distressing symptoms of chronic urticaria
• The overall duration and frequency of urticarial episodes

Chronic idiopathic urticaria is defined as recurrent wheals and/or angioedema lasting more than 6 weeks for which no identifiable cause can be found. It significantly affects quality of life — Fexofenadine is endorsed by international allergy guidelines (EAACI/WAO) as a first-line treatment for CIU.

Oral Suspension — Additional Pediatric Indication

The oral suspension formulation of Fexofenadine is also approved for the relief of chronic idiopathic urticaria symptoms in children from 6 months of age — extending its use to a younger age group than the tablet formulation.

Non-Sedating Antihistamines (Second-Generation H1 Histamine Receptor Inverse Agonists)

Afexa 180 mg is a potent, selective, second-generation peripheral H1-histamine receptor inverse agonist. It is the active carboxylic acid metabolite of Terfenadine — a first-generation antihistamine that was withdrawn from the market due to cardiac safety concerns. Fexofenadine retains the full antihistaminic efficacy of Terfenadine while eliminating its cardiac toxicity risk.

The Allergic Response — Background

Understanding the mechanism of Fexofenadine requires understanding the allergic cascade it interrupts:

1. Exposure to an allergen (pollen, dust mites, pet dander) triggers the degranulation of mast cells and basophils in sensitized individuals.
2. These cells release histamine and other inflammatory mediators (leukotrienes, prostaglandins, cytokines) into surrounding tissues.
3. Histamine binds to and activates H1 receptors on sensory nerves, blood vessels, airway smooth muscle, and mucosal glands — producing the classic symptoms of allergy: itching, sneezing, rhinorrhea, lacrimation, urticaria, and bronchoconstriction.
4. Histamine activation of H1 receptors also triggers the further release of pro-inflammatory cytokines (including interleukins) from basophils and mast cells, amplifying the allergic response.

Mechanism of Action — Inverse Agonism

Fexofenadine is considered an "inverse agonist" of the histamine H1 receptor rather than a simple competitive antagonist. This is a critical pharmacological distinction:

• H1 receptors naturally exist in equilibrium between an active (on) state and an inactive (off) state — even in the absence of histamine, some basal receptor activity occurs.
• Fexofenadine binds with high affinity and selectivity to the inactive conformation of the H1 receptor, stabilizing it in the inactive state.
• This prevents both histamine-induced receptor activation AND reduces the basal constitutive receptor activity — a more complete blockade than simple competitive antagonism.
• The result is comprehensive suppression of histamine-mediated downstream effects including cytokine release, vascular permeability, pruritus, and mucosal secretion.

Pharmacological Selectivity — CNS Safety Profile

Fexofenadine's unique benefit over first-generation antihistamines lies in its inability to cross the blood-brain barrier at therapeutic concentrations. This is because:

• Fexofenadine is a substrate of the P-glycoprotein (P-gp) efflux transporter expressed at the blood-brain barrier, which actively pumps Fexofenadine out of the CNS — preventing meaningful brain accumulation.
• As a result, Fexofenadine has virtually no effect on central H1 receptors and does not cause the sedation, cognitive impairment, or psychomotor dysfunction associated with older antihistamines.

There is no evidence that Fexofenadine carries any of the following activities that complicate older antihistamines:

• No antidopaminergic activity (no risk of extrapyramidal effects)
• No antiserotonergic activity
• No anticholinergic activity (no dry mouth, urinary retention, constipation, blurred vision, or cognitive effects)
• No significant sedative or CNS depressant effects at therapeutic doses
• No adrenergic blocking activity
• No cardiac QT-prolonging activity at therapeutic doses — unlike its predecessor Terfenadine

Pharmacokinetics

• Absorption: Rapidly absorbed from the gastrointestinal tract following oral administration. Peak plasma concentrations (C_max) are reached within approximately 1 to 3 hours after a single oral dose. The onset of antihistaminic effect typically occurs within 1 hour of administration, with peak benefit observed within 2 to 6 hours.
• Effect of food: High-fat meals have been shown to reduce C_max by approximately 20% and AUC by approximately 12%. While Fexofenadine can be taken with or without food, taking it on an empty stomach provides more rapid and complete absorption. Fruit juices (grapefruit, orange, apple) significantly reduce bioavailability and should be avoided.
• Distribution: Widely distributed in body tissues. Plasma protein binding is approximately 60–70%, primarily to albumin and alpha-1-acid glycoprotein.
• Metabolism: Fexofenadine does not undergo significant hepatic biotransformation. Approximately 5% of the total dose is metabolized by intestinal microflora (to methyl ester metabolite), but the vast majority is excreted unchanged. This minimal hepatic metabolism is a key pharmacokinetic advantage — it means Fexofenadine does not interact with other drugs through hepatic CYP450 enzyme pathways.
• Half-life: Approximately 11 to 15 hours in adults with normal renal function — supporting once-daily or twice-daily dosing. Half-life is prolonged in patients with renal impairment.
• Elimination: Primarily eliminated unchanged. Approximately 80% of the dose is excreted in the feces (via biliary excretion); approximately 11% is excreted unchanged in the urine. Since the primary elimination route is renal clearance, renal impairment significantly affects drug accumulation and requires dose adjustment.

Oral Tablets

• Fexofenadine tablets may be taken with or without food. However, taking on an empty stomach (30–60 minutes before a meal) provides faster and slightly more complete absorption.
• Swallow tablets whole with a full glass of water. Do not crush or chew tablets.
• Do not take with fruit juices — particularly grapefruit juice, orange juice, or apple juice. These juices inhibit intestinal OATP1A2 and OATP2B1 transporters, reducing Fexofenadine bioavailability by up to 36%. Always take Fexofenadine with plain water.
• For once-daily dosing, try to take at the same time each day to maintain consistent drug levels.
• For twice-daily dosing, space doses approximately 12 hours apart — for example, morning and evening.

Oral Suspension (for Children)

• Shake the bottle well before each use to ensure uniform distribution of the suspension.
• Measure the dose using the calibrated measuring spoon or oral syringe provided — do not use a regular household teaspoon, which delivers variable volumes.
• The suspension may be given with or without food, but should always be taken with water — never with fruit juices.
• The suspension may be stored at room temperature — check the specific product label for storage after opening.
• Discard unused suspension within the period stated on the label after reconstitution or opening.

Orally Disintegrating Tablets (ODT)

• Place the ODT on the tongue and allow it to dissolve completely before swallowing — do not swallow whole or chew.
• The dissolved tablet should be swallowed with a small sip of water. Do not swallow with fruit juices.
• ODT formulations are particularly useful for patients who have difficulty swallowing standard tablets and for children who can cooperate with sublingual administration.

Timing and Antacid Separation

• If an antacid containing aluminum and magnesium hydroxide is required, take it at least 2 hours before or after Fexofenadine. Antacids taken within this window significantly reduce Fexofenadine absorption.
• Fexofenadine is not affected by omeprazole or other proton pump inhibitors — these do not require dose separation.

Fexofenadine has a favorable drug interaction profile because it does not undergo significant hepatic biotransformation and therefore does not interact with other medications through hepatic CYP450 enzyme mechanisms. However, the following interactions are clinically relevant:

Erythromycin and Ketoconazole — Increased Fexofenadine Levels

Co-administration of Afexa 180 mg with erythromycin (a macrolide antibiotic) or ketoconazole (an azole antifungal) has been shown to result in a 2- to 3-fold increase in plasma Fexofenadine concentrations. The proposed mechanism is inhibition of intestinal P-glycoprotein efflux transport (which normally limits Fexofenadine absorption) and possibly reduced biliary excretion. Despite the significant pharmacokinetic interaction:

• No prolongation of the QTc cardiac interval was observed
• No increase in adverse reaction rates was reported compared to either drug given alone
• The combination is therefore not clinically contraindicated, but patients should be monitored for any unusual adverse effects at higher Fexofenadine exposure levels, particularly those with cardiovascular disease

Antacids Containing Aluminum and Magnesium Hydroxide — Reduced Absorption

Administration of antacids containing aluminum hydroxide and magnesium hydroxide gels within 15 minutes before Fexofenadine causes a clinically significant reduction in Fexofenadine bioavailability — most likely due to direct physical binding and adsorption of Fexofenadine in the gastrointestinal tract, preventing its absorption. To avoid this interaction:

• Leave a gap of at least 2 hours between taking the antacid and Fexofenadine
• Take the antacid either well before or well after Fexofenadine

Omeprazole — No Interaction

No clinically significant pharmacokinetic interaction was observed between Fexofenadine and omeprazole. Proton pump inhibitors (PPIs) can therefore be co-administered with Fexofenadine without any dose separation requirement or dose adjustment.

Fruit Juices — Reduced Absorption (Important)

Fruit juices — particularly grapefruit juice, orange juice, and apple juice — have been shown to significantly reduce the absorption of Fexofenadine. The mechanism involves inhibition of intestinal organic anion-transporting polypeptide (OATP) drug transporters (OATP1A2 and OATP2B1), which normally facilitate Fexofenadine uptake across the gut wall. Studies have demonstrated that these juices can reduce Fexofenadine bioavailability by up to 36% compared to water. Patients should be strongly advised to take Fexofenadine only with plain water, not with any fruit juice.

CNS Depressants and Sedatives

Although Fexofenadine is considered a non-sedating antihistamine, rare cases of drowsiness have been reported. Patients taking CNS depressants (benzodiazepines, opioids, alcohol, sedative hypnotics) should exercise caution, as any additive CNS depressant effect — though minimal — cannot be entirely excluded at higher plasma concentrations. The absence of significant sedative activity at standard doses makes this interaction largely theoretical at therapeutic doses.

Drugs Affecting P-glycoprotein Transport

Since Fexofenadine is a substrate of P-glycoprotein (P-gp) transporters in the gut wall and blood-brain barrier, drugs that are potent P-gp inhibitors (e.g., rifampicin, itraconazole, ritonavir) may potentially alter its absorption and CNS penetration. The clinical significance at standard antihistamine doses is considered low, but awareness of this interaction class is advisable in patients on complex medication regimens.

Afexa 180 mg has an excellent tolerability profile. In clinical trials, the frequency of side effects was similar to that observed with placebo in adults. The following adverse effects have been reported, classified by frequency:

Common Side Effects (≥1/100 to <1/10) — Reported in Clinical Trials

Adverse events reported at an incidence similar to placebo:

• Headache — most commonly reported adverse effect; generally mild
• Drowsiness — although classified as a non-sedating antihistamine, occasional mild drowsiness has been reported at higher doses; markedly less frequent than with first-generation antihistamines
• Dizziness
• Nausea

Uncommon Side Effects (≥1/1,000 to <1/100) — Reported in Clinical Trials

• Fatigue — tiredness and general malaise

Post-Marketing Adverse Effects (Frequency Unknown — Cannot be Estimated from Available Data)

The following additional adverse effects have been identified during post-marketing surveillance. Their exact frequency is not known:

Immune System Disorders

• Hypersensitivity reactions — including:
  • Angioedema — swelling of the face, lips, tongue, or throat
  • Chest tightness and dyspnea (difficulty breathing) — bronchospasm or bronchoconstriction
  • Flushing — redness and warmth of the skin
  • Systemic anaphylaxis — a rare but life-threatening generalized allergic reaction requiring immediate emergency treatment

Psychiatric Disorders

• Insomnia
• Nervousness and irritability
• Sleep disorders — including abnormal dreams or nightmares (paroniria)

Cardiac Disorders

• Tachycardia — abnormally rapid heart rate
• Palpitations — awareness of a fast, pounding, or irregular heartbeat

Gastrointestinal Disorders

• Diarrhea
• Vomiting

Skin and Subcutaneous Tissue Disorders

• Rash — skin eruptions of varying morphology
• Urticaria — hives; paradoxically, in rare cases of hypersensitivity, Fexofenadine itself can induce urticaria
• Pruritus — generalized skin itching

Pediatric-Specific Adverse Effects

In children under 2 years receiving oral suspension, the safety profile has not been as extensively studied as in older children and adults. Extra caution and monitoring are warranted in this age group (see Use in Special Populations).

If a serious hypersensitivity reaction (anaphylaxis, angioedema, severe bronchospasm) develops, discontinue Fexofenadine immediately and seek emergency medical care.

Pregnancy

There are no adequate and well-controlled clinical studies on the use of Afexa 180 mg in pregnant women. Available animal studies at doses substantially exceeding the human therapeutic dose did not indicate direct or indirect harmful effects with respect to:

• Reproductive toxicity or teratogenicity
• Embryonal or fetal development
• Parturition (labor and delivery)
• Postnatal development

However, because animal reproductive toxicology studies are not always predictive of human outcomes, Afexa 180 mg should not be used during pregnancy unless clearly necessary — i.e., when the potential benefit to the mother outweighs any theoretical risk to the fetus. Physicians should be consulted before use during pregnancy. If antihistamine therapy is required during pregnancy, a drug with a more established safety record in human pregnancy may be preferred.

Lactation

There are currently no direct data on Fexofenadine concentrations in human breast milk following administration of Afexa 180 mg. However, when the parent compound Terfenadine was administered to nursing mothers, Fexofenadine (as its active metabolite) was found to cross into human breast milk. This indicates that Fexofenadine is likely to be excreted in breast milk when taken directly. As a result:

• Afexa 180 mg is not recommended for breastfeeding mothers
• If antihistamine therapy is clinically necessary during breastfeeding, the physician should consider alternative agents with established safety data in lactation or advise temporary cessation of breastfeeding during treatment

Fertility

No human data are available on the effect of Afexa 180 mg on human fertility. In animal studies (mice), there was no effect on fertility with Fexofenadine treatment at doses tested. No fertility concerns are currently anticipated at therapeutic doses based on available preclinical data.

Limited Data in Elderly, Renally Impaired, and Hepatically Impaired Patients

As with most medications, there is only limited clinical data in elderly patients and in patients with renal or hepatic impairment. Afexa 180 mg should be administered with care in these special patient groups. Dose adjustment is required in patients with renal impairment (see Dosage and Use in Special Populations sections).

Cardiovascular Disease — Cardiac Precaution

Patients with a history of, or current, cardiovascular disease (including cardiac arrhythmias, heart failure, or ischemic heart disease) should be warned that antihistamines as a drug class have been associated with the adverse effects of tachycardia and palpitations in post-marketing reports. While Fexofenadine does not prolong the QT interval at therapeutic doses and does not carry the cardiac toxicity of Terfenadine, patients with existing cardiac conditions should be monitored for any cardiac symptoms during therapy and advised to report palpitations or rapid heartbeat to their physician promptly.

Avoid Fruit Juices

Patients should be specifically counseled to never take Fexofenadine with grapefruit juice, orange juice, or apple juice. These juices reduce Fexofenadine bioavailability by up to 36% through inhibition of intestinal drug transporters. Fexofenadine should always be taken with plain water to ensure optimal and consistent drug absorption.

Antacid Timing

Aluminum and magnesium hydroxide-containing antacids significantly reduce Fexofenadine absorption when taken within 15 minutes. Patients who need antacids should leave a minimum gap of 2 hours between antacid intake and Fexofenadine to avoid this interaction.

Effects on Driving and Operating Machinery

On the basis of Fexofenadine's pharmacodynamic profile (no CNS penetration at therapeutic doses) and the low incidence of adverse CNS reactions in clinical trials, Afexa 180 mg is unlikely to produce an effect on the ability to drive or operate machinery. In objective psychomotor testing, Fexofenadine has been shown to have no significant effects on central nervous system function, speed of reaction, or alertness — allowing patients to drive and perform tasks requiring concentration.

However, because rare individual sensitivity to any medication cannot be predicted, it is advisable for patients to assess their own personal response to Fexofenadine before driving or undertaking complex tasks — particularly when initiating therapy. This is consistent with the general precaution applicable to any medication.

Hypersensitivity Reactions

Although rare, serious hypersensitivity reactions including anaphylaxis and angioedema have been reported with Fexofenadine. Patients should be instructed to discontinue Fexofenadine immediately and seek emergency medical care if they develop symptoms of anaphylaxis, angioedema (swelling of the face, throat, or tongue), severe difficulty breathing, or significant urticaria. A history of allergy to Terfenadine should prompt caution.

Afexa 180 mg has an excellent safety margin with a wide therapeutic index. The following is known from overdose data:

Symptoms of Overdose

• Dizziness
• Drowsiness
• Fatigue
• Dry mouth

Safety Data from High-Dose Studies

In clinical pharmacokinetic and safety studies:

• Single doses of up to 800 mg were administered to healthy subjects without the development of clinically significant adverse reactions compared to placebo
• Doses of up to 690 mg twice daily for 1 month were administered without clinically important adverse reactions
• Doses of 240 mg once daily for 1 year were administered without clinically meaningful adverse reactions

The maximum tolerated dose has not been formally established. These data suggest that accidental overdose at commonly available tablet strengths (60 mg, 120 mg, 180 mg) is unlikely to cause serious harm in otherwise healthy individuals.

Management of Overdose

• There is no specific antidote for Fexofenadine overdose
• Standard measures to remove unabsorbed drug should be considered if the overdose was recent (activated charcoal within 1 hour, if the patient is alert and can protect their airway)
• Symptomatic and supportive treatment is recommended — monitor vital signs and neurological status
• Hemodialysis does not effectively remove Fexofenadine from the blood due to its protein binding and pharmacokinetic properties — dialysis is not useful in managing Fexofenadine overdose

In the event of suspected overdose, contact a poison control center or seek emergency medical care immediately.

• Store tablets below 25°C–30°C, in a cool, dry place away from direct light and heat.
• Keep all formulations out of the reach of children.
• Do not use any formulation after the expiry date printed on the packaging or label.
• Store in the original blister pack or container to protect from humidity and light.
• Oral suspension (before reconstitution): Store at room temperature below 25°C–30°C, protected from light and moisture.
• Oral suspension (after opening): Store at room temperature below 25°C, away from direct sunlight. Shake well before each use. Most oral suspension products should be used within 30 days of opening — check the specific product label for the stated shelf-life after opening. Do not freeze the suspension.
• Avoid storing near sources of heat (ovens, radiators) or in humid environments (bathroom medicine cabinets) as these conditions may degrade the product.
• Do not freeze any Fexofenadine formulation.

Patients with Renal Impairment

The pharmacokinetics of Fexofenadine are significantly altered in patients with renal impairment. Since the primary elimination route of Fexofenadine is renal, reduced kidney function leads to decreased drug clearance, increased bioavailability, and a prolonged half-life. These pharmacokinetic changes substantially increase systemic drug exposure:

• In patients with mild renal impairment: half-life and plasma concentrations are modestly increased
• In patients with moderate to severe renal impairment: half-life may be prolonged to more than 20 hours compared to the normal 11–15 hours

Based on these increases in bioavailability and half-life, a starting dose of 60 mg once daily is recommended in all patients with decreased renal function. The dose should not be increased further without clinical reassessment of renal function and therapeutic response. Hemodialysis does not effectively remove Fexofenadine from the bloodstream.

Patients with Hepatic Impairment

Moderate to severe hepatic disease does not substantially affect the pharmacokinetics of Fexofenadine. Since Fexofenadine undergoes minimal hepatic metabolism, liver impairment does not significantly impair its clearance. No dose adjustment is required for hepatic impairment based on currently available data. However, as there is limited data in patients with severe hepatic disease, caution and clinical monitoring are advisable.

Elderly Patients (Age ≥65 Years)

In clinical trials, adverse events in elderly patients (≥65 years) were similar in type and frequency to those in patients under 65 years of age — Fexofenadine is well tolerated in older adults. However, the pharmacokinetics of Fexofenadine are altered in individuals over 65 years, with increased bioavailability due to reduced renal clearance associated with age-related decline in kidney function. Elderly patients should therefore be started at the lowest effective dose and monitored for any age-related accumulation effects. No specific dose adjustment guideline is defined for age alone, but awareness of increased drug exposure is important.

Pediatric Patients (Children)

Fexofenadine has been studied and is approved for use in children across different age groups:

• 6 months to less than 2 years: Oral suspension only; approved for chronic idiopathic urticaria at 15 mg (2.5 ml) twice daily. The safety and efficacy in this age group are based on limited data — use under close medical supervision.
• 2 to 11 years: Oral suspension (30 mg/5 ml twice daily) for both allergic rhinitis and chronic idiopathic urticaria.
• 6 to 11 years: Tablets (30 mg twice daily) approved as an alternative to the suspension.
• 12 years and above: Full adult tablet dosing (60 mg, 120 mg, or 180 mg).

Fexofenadine is not approved for use in children under 6 months of age. Renal dosing adjustments apply across all pediatric age groups if renal impairment is present.