Loratadine - uses, side effects, etc.

Mechanism

Loratadine is a long-acting, second-generation, non-sedating tricyclic antihistamine (piperidine derivative) with selective antagonism of peripheral histamine H1 receptors. Loratadine selectively inhibits H1 receptors located mainly on respiratory smooth muscle cells, vascular endothelial cells, gastrointestinal tract and immune cells. Unlike first-generation antihistamines such as diphenhydramine, loratadine is a competitive histamine antagonist and cannot cross the blood-brain barrier. Therefore, it does not affect neurons in the central nervous system, preventing daytime drowsiness or sedation.

Loratadine binds to H1 receptors in various cells, causing reduced vascular permeability (preventing edema and flushing), reducing smooth muscle tone (bronchodilation), and reducing peripheral nociceptor activation (reducing pain and itching) ). At high concentrations, second-generation antihistamines such as loratadine inhibit histamine release from mast cells and basophils, thereby reducing ICAM-1 expression in epithelial cells and inhibiting type 1 hypersensitivity reactions (e.g. Hay fever, urticaria, itching, edema). There is also evidence that second-generation antihistamines have anti-inflammatory properties.

Loratadine has a rapid onset of action; its onset of action occurs within 1 to 3 hours, its effects peak within 8 to 12 hours, and it is eliminated through fecal and renal routes. Its half-life is approximately 8 hours, and the half-life of its active metabolite is 28 hours. It is metabolized primarily in the liver via the CYP450 pathway (especially CYP 3A4) to its active metabolite decarboethoxyloratadine.

using drugs

Loratadine is administered as tablets (chewable lozenges or ODT - orally disintegrating tablets), liquid-filled capsules, or syrup (1 mg/mL solution). Although it is recommended to take oral medications on an empty stomach, they can be taken with or without food. Place the dispersible tablet in your mouth and allow it to dissolve. Patients can swallow with or without water. Research into other formulations aimed at improving bioavailability is ongoing.

For allergic rhinitis:

• Adolescents, Adults, and Elderly: 10 mg PO once daily or 5 mg twice daily; do not exceed 10 mg in 24 hours.
• Pediatrics: 2 to 5 years: 5 mg orally daily; 6 years and older: 10 mg orally daily. ODT preparations are not recommended for use in young children.

For hives:

• Adolescents, Adults, and the Elderly: 10 mg orally daily: Dosage should generally not exceed 10 mg in a 24-hour period. However, some patients may benefit from higher doses—clinicians should weigh the risks versus benefits.
• Pediatrics 6 years and older: 10 mg orally daily as needed.

In cases of renal and hepatic insufficiency, it is recommended to increase the dosing interval to 48 hours as follows:

Patients with renal insufficiency (GFR less than 30 mL/min):

• Adults: 10 mg orally every other day.
• Children 2 to 6 years: 5 mg PO every other day.
• Children 6 years and older: 10 mg orally every other day.

Patients on peritoneal or hemodialysis should dose every 48 hours; no supplementary doses are required after dialysis.

Patients with liver damage:

• Adults: 10 mg orally every other day.
• Children 2 to 6 years: 5 mg orally every other day.
• Children 6 years and older: 10 mg orally every other day.

The half-life of this drug increases with the severity of liver disease.

There is variability in the half-life of loratadine in the elderly, and clinicians need to be aware of this factor when initiating treatment in this age group.

Negative Effects

Although loratadine is a relatively safe and effective drug for the treatment of allergic rhinitis, its main adverse effects include headache, dizziness, and gastrointestinal discomfort (diarrhoea, abdominal pain, nausea, and vomiting). Loratadine may also cause sedation (a rare side effect), dilated pupils, and dry mouth. These effects are primarily due to the anticholinergic effects of the drug.

Patients should not take loratadine with other CNS depressants such as diphenhydramine, dextromethorphan, or pseudoephedrine as it may cause dose-related sedation. There is no evidence that coadministration of loratadine and oral contraceptives increases adverse events.

Taboo

Contraindications to loratadine include patients who are allergic to the drug or components of the preparation, and there are strong contraindications in children under 2 years of age due to its antihistamine properties, which may lead to central nervous system irritation or seizures in younger patients.

Because this drug has anticholinergic effects that may cause exacerbations, it should be used with caution in people with asthma or COPD.

Although this drug is not generally sedating, caution should be advised in patients who perform activities that require concentration (such as driving a motor vehicle) as it may cause some drowsiness.

Patients diagnosed with phenylketonuria (PKU) should consult their primary care physician before taking loratadine. Some of its formulations (such as orally disintegrating tablets) may contain phenylalanine, which may worsen the symptoms of phenylketonuria.

Although loratadine, like any drug, does not have dangerously significant drug-drug interactions, thorough medication reconciliation is necessary. Drugs that affect the CYP450 enzyme system may interact, requiring adjustment of treatment regimen.

Caution is advised in patients with hepatic disease or hepatic impairment as loratadine is extensively metabolized by the liver and dosage adjustments may need to be made according to healthcare guidelines. Likewise, caution should be exercised in individuals with renal failure or impairment as loratadine concentrations may be elevated in such patients, requiring dose adjustment.

According to the American College of Obstetricians and Gynecologists, loratadine should be safe to use during pregnancy; based on limited human data, there is no expected risk of harm to the fetus; the drug is a pregnancy category B drug and is not recommended during lactation. Use with caution; nursing mothers may use this drug for short periods of time during breastfeeding; both loratadine and its active metabolites readily pass into breast milk. Based on the characteristics of the drug and the limited human data available, there is no known risk of harm to infants.

monitor

Patients taking loratadine need to be monitored for symptom relief, sedation, and any anticholinergic effects (e.g., mydriasis and dryness of the oral mucosa).

For patients with impaired renal or hepatic function, the primary care physician also needs to closely monitor renal and hepatic function and adjust drug dosage accordingly.

The cardiac function of individuals with a history of cardiac arrhythmias should also be monitored to prevent loratadine overadministration.

Loratadine should be stored in a cool, dry place between 68 and 77 degrees Fahrenheit.

toxicity

Patients, especially the elderly, may develop loratadine-induced cardiotoxicity, including cardiac arrhythmias and QT prolongation, if doses higher than the recommended 24-hour dose are taken. Although rare, overdose of loratadine may result in significant toxicity, including agitation and symptoms of anticholinergic syndrome. Symptoms include, but are not limited to, mydriasis, urinary retention, tachycardia, and skin flushing.

Treatment options for loratadine toxicity may include providing vomiting (except in patients with impaired consciousness), supplemental oxygen, and cardiac monitoring. Clinicians may administer sodium bicarbonate to treat cardiac arrhythmias and QT prolongation in patients suspected of being intoxicated. Benzodiazepines can relieve agitation due to their high therapeutic index. Adults with symptoms of anticholinergic toxicity due to loratadine intoxication may be treated with physostigmine detoxification (recommended dose is 0.5 to 2 mg intravenously). It is recommended that only a medical toxicologist oversee detoxification treatment.

There is no evidence that loratadine has a potential for abuse or dependence.

Improve healthcare team outcomes

Loratadine has been shown to be an effective and safe medication for the relief of allergic rhinitis symptoms and the treatment of hives. This medication is available over-the-counter; therefore, pharmacists must educate patients on the therapeutic dosage of the medication and check their medication profile for any potential interactions. Primary care clinicians (MD, DO, PA, NP) must educate patients on the importance of reading labels to avoid taking more than recommended doses to prevent any drug-related toxicity. Although loratadine is a relatively safe drug, health care providers should inform patients of all side effects associated with the drug, and as with adding or discontinuing any drug, medication reconciliation is necessary.

Healthcare providers should also check liver and kidney function before prescribing medications to individuals with hepatic and renal impairment. Nurse practitioners should obtain a complete mediation history from the patient at each visit, including over-the-counter medications and supplements, and chart it so that all interprofessional health care team members have a complete picture of the patient. Nursing can also enhance patient counseling regarding the correct dosage and administration of loratadine and observe adverse effects and patient compliance. Pharmacists can enhance dosing and administration parameters and check for drug-drug interactions. As noted above, collaborative communication among all members of the interprofessional team is required to ensure optimal outcomes for loratadine-treated patients.