COLDEEZE

Indications

• Nasal congestion
• Hypotension (particularly in acute settings)
• Vasopressor support during anesthesia

Dosage

Children: Refer to the BNF for Children for specific dosing information, as it varies based on age and indication.

Adults: For the treatment of hypotension, the recommended initial dose is 0.16–0.33 mL/minute as an intravenous infusion, adjusted according to blood pressure response. For nasal congestion, 0.25 to 0.5 mL of the 0.5% solution may be applied topically.

Mechanism of action

Phenylephrine primarily acts as a selective agonist for α1-adrenergic receptors. Activation of these receptors results in vasoconstriction of blood vessels, leading to increased systemic vascular resistance and blood pressure. It does not significantly stimulate β-adrenergic receptors, which makes it less effective at increasing heart rate compared to other sympathomimetics.

Pharmacodynamics

Phenylephrine's pharmacodynamic effects include increased peripheral vascular resistance and blood pressure due to its vasoconstrictive action. Its decongestant effects arise from vasoconstriction of nasal mucosal blood vessels, reducing swelling and congestion. The duration of action is dose-dependent and can vary based on the route of administration.

Pharmacokinetics

Phenylephrine is absorbed after oral administration but has a significant first-pass metabolism, which reduces its bioavailability. It is metabolized primarily in the liver and has a half-life of about 2.5 to 3 hours. The drug is excreted in urine, primarily as metabolites. The onset of action varies with the route of administration, with intravenous administration providing the most rapid effect.

Adverse effects

• Hypertension
• Reflex bradycardia
• Headache
• Nausea
• Vomiting
• Palpitations

Precautions

• Use with caution in patients with hypertension
• Monitor blood pressure frequently
• Use during pregnancy only if potential benefit outweighs risk

Pregnancy

Manufacturer advises use if potential benefit outweighs risk-may reduce placental perfusion and induce fetal bradycardia.

Storage

Store at room temperature, protect from light.

Formulations

• Phenylephrine hydrochloride 2.5mg tablets
• Phenylephrine hydrochloride 5mg tablets
• Phenylephrine hydrochloride 10mg tablets
• Phenylephrine hydrochloride solution for injection

Indications

• Topical antiseptic for skin disinfection
• Preservative in ophthalmic solutions
• Disinfectant for medical instruments
• Antiseptic wipes for hand hygiene

Dosage

Children: Refer to specific product guidelines for exact dosing, as it varies by formulation and intended use.

Adults: Refer to specific product guidelines for exact dosing, as it varies by formulation and intended use.

Mechanism of action

Benzylconium acts by disrupting the cell membrane of microorganisms. It interacts with the phospholipid bilayer of the cell membrane, leading to increased permeability, leakage of cellular contents, and ultimately cell death. This mechanism is common among quaternary ammonium compounds, allowing them to be effective antiseptics and disinfectants.

Pharmacodynamics

Benzylconium exhibits broad-spectrum antimicrobial activity. Its effectiveness varies based on concentration and the type of microorganism. It is particularly effective against Gram-positive bacteria, with variable activity against Gram-negative bacteria. Its bactericidal activity is enhanced in the presence of organic matter, although high concentrations can be toxic to human tissues.

Pharmacokinetics

Benzylconium is poorly absorbed through intact skin and mucous membranes, which limits systemic exposure. The compound is primarily used topically, and when applied, it exerts local effects at the site of application. Its elimination is primarily through metabolic pathways, and it is generally excreted via urine in negligible amounts.

Adverse effects

• Local irritation
• Allergic reactions
• Dermatitis
• Sensitization

Precautions

• Use with caution in patients with a history of hypersensitivity to benzalkonium chloride or other quaternary ammonium compounds
• Avoid contact with eyes and mucous membranes
• Not suitable for use on open wounds or damaged skin

Pregnancy

Safety during pregnancy has not been established; use only if clearly needed

Breast-feeding

Excretion in breast milk is unknown; use with caution

Storage

Store in a cool, dry place, away from direct sunlight

Formulations

• Topical solution
• Cream
• Ointment
• Aqueous solution
• Wipes

Indications

• Hypotension in surgical settings
• Nasal decongestion
• Mydriasis for ophthalmic procedures
• Management of shock states

Dosage

Adults: For intravenous administration, initial doses typically range from 100 to 500 micrograms, repeated as necessary, with careful monitoring of blood pressure. For nasal decongestion, phenylephrine is commonly administered as a 10 mg oral dose every

Mechanism of action

Phenylephrine exerts its effects primarily through agonism of alpha-1 adrenergic receptors, which results in vasoconstriction and mydriasis. The stimulation of these receptors inhibits the production of cyclic adenosine-3',5'-monophosphate (cAMP) by inhibiting adenyl cyclase, leading to increased peripheral vascular resistance and elevated blood pressure. Additionally, phenylephrine indirectly promotes the release of norepinephrine from storage sites, further enhancing its vasoconstrictive effects.

Pharmacodynamics

Phenylephrine causes an increase in blood pressure and local vasoconstriction. Its ophthalmic formulations can induce mydriasis for 3-8 hours, while intravenous administration has a rapid onset with an effective half-life of about 5 minutes and an elimination half-life of approximately 2.5 hours. Caution is advised regarding potential side effects such as hypertension, arrhythmias, and rebound miosis with ophthalmic use, and bradycardia, allergic reactions, and tissue damage with intravenous use.

Pharmacokinetics

Phenylephrine is rapidly absorbed following intravenous administration, leading to a quick elevation in blood pressure. The drug undergoes metabolism primarily in the liver and is eliminated through urine. The pharmacokinetic profile indicates a short effective half-life which necessitates frequent dosing in continuous infusion settings for maintaining blood pressure levels.

Contra-indications

• Severe hypertension
• Hypersensitivity to phenylephrine
• Severe coronary artery disease
• Narrow-angle glaucoma

Adverse effects

• Hypertension
• Reflex bradycardia
• Arrhythmias
• Headache
• Dizziness
• Nausea
• Vomiting
• Local irritation (ophthalmic use)

Interactions

• MAO inhibitors may enhance the hypertensive effect
• Tricyclic antidepressants may increase the pressor response
• Concurrent use with oxytocic drugs may increase the risk of hypertension
• Can interact with other sympathomimetics

Precautions

• Use with caution in patients with hypertension, hyperthyroidism, or diabetes mellitus
• Monitor blood pressure regularly during treatment
• Caution in patients with cardiovascular disease
• Use with caution in elderly patients

Pregnancy

Phenylephrine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Limited data available.

Breast-feeding

It is not known whether phenylephrine is excreted in human milk. Caution is advised when administered to nursing mothers.

Storage

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

Formulations

• Ophthalmic solution
• Injectable solution
• Oral tablet

Indications

• Allergic rhinitis
• Urticaria
• Insomnia
• Motion sickness

Dosage

Children: Refer to the BNF for Children for appropriate paediatric dosing.

Adults: Refer to the BNF for appropriate adult dosing.

Mechanism of action

Thenyldiamine exerts its effects by antagonizing H1 histamine receptors, thereby preventing the binding of histamine and subsequent activation of the receptors. This action reduces the symptoms of allergic reactions, including itching, sneezing, and nasal congestion.

Pharmacodynamics

As a first-generation antihistamine, thenyldiamine is known for its sedative effects, which are attributed to its ability to cross the blood-brain barrier. This sedative effect can be beneficial in certain clinical situations but may also lead to drowsiness and impair cognitive and motor functions.

Pharmacokinetics

Thenyldiamine is absorbed well from the gastrointestinal tract. It undergoes hepatic metabolism and has a half-life that allows for multiple daily dosing. The drug is excreted primarily in the urine, with both unchanged drug and metabolites present.

Adverse effects

• Drowsiness
• Dry mouth
• Dizziness
• Nausea
• Blurred vision

Precautions

• Use with caution in patients with glaucoma
• Caution in patients with prostatic hypertrophy
• May cause sedation, caution when driving or operating machinery

Pregnancy

Safety in pregnancy has not been established. Use only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

Use with caution. It is not known whether thenyldiamine is excreted in human milk. Consider the importance of the drug to the mother.

Storage

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

Formulations

• Tablets
• Syrup

Mechanism of action

Phenylephrine is an alpha-1 adrenergic agonist that mediates vasoconstriction and mydriasis depending on the route and location of administration. Systemic exposure to phenylephrine also leads to agonism of alpha-1 adrenergic receptors, raising systolic and diastolic pressure as well as peripheral vascular resistance. Increased blood pressure stimulates the vagus nerve, causing reflex bradycardia. Phenylephrine acts predominantly by a direct effect on alpha-adrenergic receptors. In therapeutic doses, the drug has no substantial stimulant effect on the beta-adrenergic receptors of the heart (beta1-adrenergic receptors) but substantial activation of these receptors may occur when larger doses are given. Phenylephrine does not stimulate beta-adrenergic receptors of the bronchi or peripheral blood vessels (beta2-adrenergic receptors). It is believed that alpha-adrenergic effects result from the inhibition of the production of cyclic adenosine-3',5'-monophosphate (cAMP) by inhibition of the enzyme adenyl cyclase, whereas beta-adrenergic effects result from stimulation of adenyl cyclase activity. Phenylephrine also has an indirect effect by releasing norepinephrine from its storage sites.

Pharmacodynamics

Phenylephrine is an alpha-1 adrenergic agonist that raises blood pressure, dilates the pupils, and causes local vasoconstriction. Ophthalmic formulations of phenylephrine act for 3-8 hours while intravenous solutions have an effective half life of 5 minutes and an elimination half life of 2.5 hours. Patients taking ophthalmic formulations of phenylephrine should be counselled about the risk of arrhythmia, hypertension, and rebound miosis. Patients taking an intravenous formulation should be counselled regarding the risk of bradycardia, allergic reactions, extravasation causing necrosis or tissue sloughing, and the concomitant use of oxytocic drugs.