FEBREX PLUS TABLETS

Indications

• Allergic rhinitis
• Allergic conjunctivitis
• Urticaria
• Angioedema
• Common cold symptoms

Dosage

Children: Refer to the specific guidelines in the BNF for Children for dosing information.

Adults: Refer to the specific guidelines in the BNF for dosing information.

Mechanism of action

Chlorphenamine exerts its effects by antagonizing the H1 histamine receptors, which prevents histamine from binding and activating these receptors. This action reduces the symptoms associated with allergic reactions, such as itching, sneezing, and runny nose. Additionally, by blocking central H1 receptors, chlorphenamine can also induce sedation.

Pharmacodynamics

Chlorphenamine has a rapid onset of action typically within 30 minutes, with its effects lasting for 4 to 6 hours. The sedative effects are more pronounced in first-generation antihistamines like chlorphenamine, which can cause drowsiness by inhibiting neurotransmission in the central nervous system. Overall, chlorphenamine provides relief from allergic symptoms but may also impair psychomotor performance.

Pharmacokinetics

Chlorphenamine is well absorbed from the gastrointestinal tract; peak plasma concentrations are usually reached within 2 to 6 hours after oral administration. It is extensively metabolized in the liver, primarily via the cytochrome P450 enzyme system, and has a half-life of approximately 12 to 15 hours. The drug is excreted mainly in urine, with both unchanged drug and metabolites present. Due to its lipophilicity, chlorphenamine can readily cross the blood-brain barrier, contributing to its sedative effects.

Contra-indications

• Hypersensitivity to chlorphenamine or any component of the formulation
• Severe liver impairment
• Concurrent use of monoamine oxidase inhibitors (MAOIs)

Adverse effects

• Drowsiness
• Dizziness
• Dry mouth
• Blurred vision
• Urinary retention
• Constipation
• Gastrointestinal disturbances
• Hypotension
• Tachycardia

Interactions

• Increased sedative effects when used with alcohol or other central nervous system depressants
• May enhance the effects of anticholinergic drugs
• Potential interaction with MAOIs leading to hypertensive crisis
• May reduce the effectiveness of certain antihypertensive medications

Precautions

• Caution in patients with glaucoma
• Caution in patients with prostatic hypertrophy
• Use with caution in elderly patients or those with cardiovascular disease
• Should be used with caution in patients with epilepsy

Pregnancy

Chlorphenamine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Consult healthcare provider for guidance.

Breast-feeding

Chlorphenamine is excreted in breast milk. Caution should be exercised when administering to breastfeeding women.

Storage

Store in a cool, dry place, away from light. Keep out of reach of children.

Formulations

• Oral tablets
• Oral syrup
• Injectable solution

Indications

• Mild to moderate pain
• Fever
• Nasal congestion due to colds or allergies

Dosage

Children: Refer to the BNF for Children for specific dosing recommendations.

Adults: Refer to the BNF for specific dosing recommendations.

Mechanism of action

Paracetamol acts by inhibiting cyclooxygenase (COX) enzymes, leading to a decrease in prostaglandin synthesis, particularly in the central nervous system. This action reduces pain perception and lowers fever. Phenylephrine exerts its effects by stimulating alpha-1 adrenergic receptors on vascular smooth muscle, resulting in vasoconstriction and reduced swelling in nasal passages.

Pharmacodynamics

Paracetamol exhibits analgesic and antipyretic properties, effectively relieving mild to moderate pain and reducing fever. Its effects are typically seen within 30 minutes to 1 hour after oral administration. Phenylephrine’s decongestant effect is evident shortly after administration, leading to reduced nasal congestion and improved airflow through the nasal passages.

Pharmacokinetics

Paracetamol is rapidly absorbed from the gastrointestinal tract, with peak plasma concentrations occurring approximately 30 to 60 minutes after oral dosing. It is primarily metabolized in the liver via conjugation and is excreted in urine. The elimination half-life is approximately 1 to 4 hours. Phenylephrine is also absorbed quickly, with peak effects occurring within 1 to 2 hours. It undergoes extensive first-pass metabolism, and its half-life ranges from 2 to 3 hours.

Contra-indications

• Severe hepatic impairment
• Hypersensitivity to paracetamol, phenylephrine or any of the excipients
• Severe hypertension
• Concurrent use of monoamine oxidase inhibitors (MAOIs)

Adverse effects

• Nausea
• Vomiting
• Rash
• Headache
• Hypertension
• Tachycardia
• Insomnia
• Dizziness
• Palpitations

Interactions

• Alcohol may increase the risk of liver damage when taken with paracetamol
• Phenylephrine may interact with MAOIs, leading to hypertensive crisis
• Tricyclic antidepressants may enhance the pressor effects of phenylephrine
• Antihypertensive medications may have their effects reduced by phenylephrine

Precautions

• Use with caution in patients with cardiovascular disease
• Caution in patients with liver disease or heavy alcohol use
• Monitor blood pressure in patients with hypertension
• Avoid prolonged use of paracetamol at high doses

Pregnancy

Paracetamol is generally considered safe in pregnancy; however, phenylephrine should be used with caution and only if the benefits outweigh the risks.

Breast-feeding

Paracetamol is excreted in breast milk in small amounts and is generally considered safe. Phenylephrine should be used with caution as there is limited data on its excretion in breast milk.

Storage

Store in a cool, dry place away from direct sunlight. Keep out of reach of children.

Formulations

• Tablets
• Liquid suspensions
• Effervescent tablets
• Syrups