ALCOF-C

Indications

• Pruritus
• Eczema
• Acne
• Rosacea

Dosage

Children: For children aged 12-17 years, apply up to 3 grams 3-4 times a day, ensuring coverage is less than 10% of body surface area.

Adults: Apply thinly to the affected area 1-2 times a day. Maximum application should cover less than 10% of body surface area, with a total daily maximum of 12 grams.

Mechanism of action

Levomenthol primarily activates the cold-sensitive TRPM8 receptors in the skin. This stimulation leads to a feeling of coolness by inhibiting calcium ion currents in neuronal membranes. Additionally, menthol may exhibit analgesic properties through kappa-opioid receptor agonism, further contributing to its pain-relieving effects.

Pharmacodynamics

Levomenthol is a covalent organic compound that can be synthesized or extracted from peppermint and other mint oils. It induces a cooling sensation when applied topically, inhaled, or ingested, by stimulating cold-sensitive receptors located in the skin. Notably, this effect occurs without a decrease in actual skin temperature, making it useful in topical formulations for managing discomfort.

Pharmacokinetics

Levomenthol is absorbed through the skin upon topical application. Its effects are localized, and it does not significantly enter systemic circulation when used as directed. The onset of action is typically rapid, providing immediate symptomatic relief from conditions like itching and irritation.

Contra-indications

• Severe heart disease
• Severe hepatic impairment
• Glaucoma
• Urinary retention
• History of mania or arrhythmias

Adverse effects

• Drowsiness
• Dizziness
• Headache
• Nausea
• Vomiting
• Dry mouth
• Dry eyes
• Diarrhea
• Constipation
• Skin reactions
• Altered taste
• Blurred vision
• Suicidal behaviors

Interactions

• Tricyclic antidepressants
• Other central nervous system depressants

Precautions

• Avoid application to large areas of the skin
• Use caution in patients with a history of psychiatric disorders
• Caution advised for driving and skilled tasks due to potential somnolence or dizziness

Pregnancy

Manufacturer advises use only if potential benefit outweighs risk.

Breast-feeding

Manufacturer advises use only if potential benefit outweighs risk.

Storage

Store in a cool, dry place, protected from light.

Formulations

• AquaSoothe 1% cream (Menthol 10 mg per 1 gram)
• AquaSoothe 2% cream (Menthol 20 mg per 1 gram)
• Arjun 0.5% cream (Menthol 5 mg per 1 gram)
• Arjun 1% cream (Menthol 10 mg per 1 gram)
• Dermacool 0.5% cream (Menthol 5 mg per 1 gram)
• Dermacool 1% cream (Menthol 10 mg per 1 gram)
• Menthoderm 0.5% cream (Menthol 5 mg per 1 gram)
• Menthoderm 1% cream (Menthol 10 mg per 1 gram)
• Menthoderm 2% cream (Menthol 20 mg per 1 gram)
• Menthoderm 5% cream (Menthol 50 mg per 1 gram)

Indications

• Chronic idiopathic urticaria
• Perennial allergic rhinitis
• Seasonal allergic rhinitis
• Allergic asthma
• Physical urticaria
• Atopic dermatitis

Dosage

Children: For children aged 6 to 12 years, the dosage is typically 5 mg to 10 mg once daily depending on the severity of symptoms. For children aged 2 to 6 years, the usual dose is 2.5 mg to 5 mg once daily. Specific dosing should refer to the BNF for Children.

Adults: The typical adult dose is 10 mg once daily, which can be adjusted based on the severity of symptoms and patient response.

Mechanism of action

Cetirizine selectively inhibits peripheral H1 receptors, effectively blocking the action of histamine, which is responsible for allergic symptoms. It has demonstrated negligible anticholinergic and antiserotonergic effects, and studies indicate minimal penetration into the central nervous system, reducing the likelihood of sedation.

Pharmacodynamics

Cetirizine exhibits antihistaminic activity that effectively minimizes or eliminates symptoms of various allergic conditions such as chronic idiopathic urticaria and allergic rhinitis. It has anti-inflammatory properties that may assist in asthma management and can significantly reduce the duration and dosage of topical anti-inflammatory treatments for conditions like atopic dermatitis. Its effects can be observed within 20 minutes of administration, lasting up to 24 hours.

Pharmacokinetics

Cetirizine is well absorbed orally with peak plasma concentrations occurring approximately 1 hour after dosing. It has a half-life of about 8 hours, allowing for once-daily dosing in most cases. The drug is primarily excreted in the urine, with minimal hepatic metabolism, making it suitable for patients with liver impairment.

Adverse effects

• dry mouth
• drowsiness
• fatigue
• headache
• nausea

Precautions

• Use with caution in patients with renal impairment
• Caution advised in individuals with a history of seizures

Pregnancy

Cetirizine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

Cetirizine is excreted in breast milk; caution is advised when administered to breastfeeding mothers.

Storage

Store at room temperature, away from moisture and heat.

Formulations

• tablets
• oral solution
• syrup

Indications

• Cough
• Pseudobulbar affect

Dosage

Children: Refer to the BNF for Children for specific dosing information tailored to paediatric patients.

Adults: Refer to the BNF for specific dosing guidelines based on the formulation and clinical context.

Mechanism of action

Dextromethorphan acts as a low-affinity uncompetitive antagonist of NMDA receptors and as an agonist at sigma-1 receptors. It also antagonizes α3/β4 nicotinic receptors. The clinical effects are thought to arise from NMDA receptor blockade and serotonin (5-HT) uptake inhibition, which may lead to increased serotonin receptor stimulation. However, the precise mechanisms by which these actions translate into therapeutic effects remain incompletely understood.

Pharmacodynamics

Dextromethorphan is considered an opioid-like molecule with a moderate therapeutic window, indicating that while it is effective at standard doses, higher doses can lead to intoxication. It has a moderate duration of action, making it suitable for use in cough management. Due to its potential for abuse and risk of intoxication, patients are advised to use it cautiously.

Pharmacokinetics

Dextromethorphan is metabolized primarily in the liver through the cytochrome P450 enzyme system, leading to the formation of its active metabolite, dextrorphan. The pharmacokinetics may be influenced by individual variations in metabolic pathways, which can affect the drug's efficacy and safety profile.

Contra-indications

• Hypersensitivity to dextromethorphan or any of its components
• Concurrent use with monoamine oxidase inhibitors (MAOIs)
• Severe respiratory insufficiency or asthma
• Persistent cough due to smoking, emphysema, or chronic bronchitis

Adverse effects

• Dizziness
• Nausea
• Vomiting
• Drowsiness
• Confusion
• Constipation
• Abdominal discomfort
• Euphoria or dysphoria
• Serotonin syndrome (when used with serotonergic drugs)

Interactions

• May interact with MAOIs, leading to serious side effects
• Potential interactions with other CNS depressants, leading to increased sedation
• May enhance the effects of alcohol
• Can interact with medications that affect serotonin levels, increasing the risk of serotonin syndrome

Precautions

• Use with caution in patients with a history of substance abuse
• Monitor use in patients with hepatic impairment
• Caution advised in patients with a history of seizures
• Should not be used in children under 2 years unless directed by a physician

Pregnancy

Dextromethorphan should be used during pregnancy only if clearly needed. Consult a healthcare provider for advice.

Breast-feeding

Dextromethorphan is excreted in breast milk. Caution is advised when administered to nursing mothers.

Storage

Store at room temperature, away from moisture and heat. Keep out of reach of children.

Formulations

• Oral syrup
• Tablets
• Capsules
• Lozenges

Indications

• Nasal congestion
• Hypotension during anesthesia
• Mydriasis for ophthalmic procedures
• Shock (as a vasopressor)

Dosage

Children: Refer to specific dosing guidelines in a relevant drug reference.

Adults: Refer to specific dosing guidelines in a relevant drug reference.

Mechanism of action

Phenylephrine selectively binds to alpha-1 adrenergic receptors, resulting in vasoconstriction of blood vessels. This action increases peripheral vascular resistance and elevates blood pressure. Additionally, it causes contraction of the smooth muscle in the nasal mucosa, leading to reduced nasal congestion.

Pharmacodynamics

The primary pharmacodynamic effect of phenylephrine is its ability to increase blood pressure through peripheral vasoconstriction. This effect is dose-dependent, with higher doses leading to more significant increases in blood pressure. It also produces mydriasis (pupil dilation) through its action on the iris dilator muscle.

Pharmacokinetics

Phenylephrine is absorbed from the gastrointestinal tract but undergoes extensive first-pass metabolism, which reduces its bioavailability. It has a rapid onset of action when administered intravenously, while oral formulations have a delayed onset. The half-life of phenylephrine varies but is generally around 2-3 hours. It is metabolized primarily by monoamine oxidase and conjugated in the liver, with metabolites excreted in the urine.

Contra-indications

• Severe hypertension
• Severe coronary artery disease
• Hypersensitivity to phenylephrine or any component of the formulation
• Concurrent use of monoamine oxidase inhibitors (MAOIs)

Adverse effects

• Hypertension
• Reflex bradycardia
• Headache
• Nausea
• Restlessness
• Insomnia
• Palpitations
• Tremors

Interactions

• Increased hypertensive effects with other sympathomimetics
• MAOIs may enhance the pressor response of phenylephrine
• Tricyclic antidepressants may potentiate the effects of phenylephrine

Precautions

• Use with caution in patients with hypertension, diabetes, hyperthyroidism, or in those with a history of seizures
• Monitor blood pressure regularly during treatment
• Use with caution in elderly patients or those with cardiovascular disease

Pregnancy

Phenylephrine is classified as category C. Use during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

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

Storage

Store at room temperature, away from moisture and light. Keep out of reach of children.

Formulations

• Oral tablets
• Oral liquid
• Intranasal spray
• Injectable solution

Mechanism of action

Menthol primarily activates the cold-sensitive TRPM8 receptors in the skin. Menthol, after topical application, causes a feeling of coolness due to stimulation of 'cold' receptors by inhibiting Ca++ currents of neuronal membranes. It may also yield analgesic properties via kappa-opioid receptor agonism.

Pharmacodynamics

Menthol is a covalent organic compound made synthetically or obtained from peppermint or other mint oils. Menthol induces a cooling sensation on the skin upon inhalation, oral ingestion, or topical application by stimulating the cold-sensitive receptors expressed on the skin, without actually causing a drop in the skin temperature.

Mechanism of action

Cetirizine, a metabolite of _hydroxyzine_, is an antihistamine drug. Its main effects are achieved through selective inhibition of peripheral H1 receptors. The antihistamine activity of cetirizine has been shown in a variety of animal and human models. _In vivo_ and _ex vivo_ animal models have shown insignificant anticholinergic and antiserotonergic effects. In clinical studies, however, dry mouth was found to be more frequent with cetirizine than with a placebo. In vitro receptor binding studies have demonstrated no detectable affinity of cetirizine for histamine receptors other than the H1 receptors. Studies with radiolabeled cetirizine administration in the rat have demonstrated insignificant penetration into the brain. _Ex vivo_ studies in the mouse have shown that systemically administered cetirizine does not occupy cerebral H1 receptors significantly. Cetirizine, a human metabolite of hydroxyzine, is an antihistamine; its principal effects are mediated via selective inhibition of peripheral H1 receptors. The antihistaminic activity of cetirizine has been clearly documented in a variety of animal and human models. In vivo and ex vivo animal models have shown negligible anticholinergic and antiserotonergic activity. In clinical studies, however, dry mouth was more common with cetirizine than with placebo. In vitro receptor binding studies have shown no measurable affinity for other than H1 receptors. Autoradiographic studies with radiolabeled cetirizine in the rat have shown negligible penetration into the brain. Ex vivo experiments in the mouse have shown that systemically administered cetirizine does not significantly occupy cerebral H1 receptors.

Pharmacodynamics

**General effects and respiratory effects** Cetirizine, the active metabolite of the piperazine H₁-receptor antagonist hydroxyzine, minimizes or eliminates the symptoms of chronic idiopathic urticaria, perennial allergic rhinitis, seasonal allergic rhinitis, allergic asthma, physical urticaria, and atopic dermatitis. The clinical efficacy of cetirizine for allergic respiratory diseases has been well established in numerous trials. **Effects on urticaria/anti-inflammatory effects** It has anti-inflammatory properties that may play a role in asthma management. There is evidence that cetirizine improves symptoms of urticaria. Marked clinical inhibition of a wheal and flare response occurs in infants, children as well as adults within 20 minutes of one oral dose and lasts for 24 h. Concomitant use of cetirizine reduces the duration and dose of topical anti-inflammatory formulas used for the treatment of atopic dermatitis.

Mechanism of action

Dextromethorphan is a low-affinity uncompetitive NMDA antagonist and sigma-1 receptor agonist. It is also an antagonist of α3/β4 nicotinic receptors. However, the mechanism by which dextromethorphan's receptor agonism and antagonism translate to a clinical effect is not well understood. Dextromethorphan (DXM) is the dextro isomer of levomethorphan, a semisynthetic morphine derivative. Although structurally similar to other /CNS depressants/, DXM does not act as a mu receptor opioid (eg, morphine, heroin). DXM and its metabolite, dextrorphan, act as potent blockers of the N-methyl-d-aspartate (NMDA) receptor. Amantadine and dextromethorphan suppress levodopa (L-DOPA)-induced dyskinesia (LID) in patients with Parkinson's disease (PD) and abnormal involuntary movements (AIMs) in the unilateral 6-hydroxydopamine (6-OHDA) rat model. These effects have been attributed to N-methyl-d-aspartate (NMDA) antagonism. However, amantadine and dextromethorphan are also thought to block serotonin (5-HT) uptake and cause 5-HT overflow, leading to stimulation of 5-HT(1A) receptors, which has been shown to reduce LID. We undertook a study in 6-OHDA rats to determine whether the anti-dyskinetic effects of these two compounds are mediated by NMDA antagonism and/or 5-HT(1A) agonism. In addition, we assessed the sensorimotor effects of these drugs using the Vibrissae-Stimulated Forelimb Placement and Cylinder tests. Our data show that the AIM-suppressing effect of amantadine was not affected by the 5-HT(1A) antagonist WAY-100635, but was partially reversed by the NMDA agonist d-cycloserine. Conversely, the AIM-suppressing effect of dextromethorphan was prevented by WAY-100635 but not by d-cycloserine. Neither amantadine nor dextromethorphan affected the therapeutic effects of L-DOPA in sensorimotor tests. We conclude that the anti-dyskinetic effect of amantadine is partially dependent on NMDA antagonism, while dextromethorphan suppresses AIMs via indirect 5-HT(1A) agonism. Combined with previous work from our group, our results support the investigation of 5-HT(1A) agonists as pharmacotherapies for LID in PD patients. Dextromethorphan (DM) is a dextrorotatory morphinan and an over-the-counter non-opioid cough suppressant. We have previously shown that DM protects against LPS-induced dopaminergic neurodegeneration through inhibition of microglia activation. Here, we investigated protective effects of DM against endotoxin shock induced by lipopolysaccharide/d-galactosamine (LPS/GalN) in mice and the mechanism underlying its protective effect. Mice were given multiple injections of DM (12.5 mg/kg, s.c.) 30 min before and 2, 4 hr after an injection of LPS/GalN (20 ug/700 mg/kg). DM administration decreased LPS/GalN-induced mortality and hepatotoxicity, as evidenced by increased survival rate, decreased serum alanine aminotransferase activity and improved pathology. Furthermore, DM was also effective when it was given 30 min after LPS/GalN injection. The protection was likely associated with reduced serum and liver tumor necrosis factor alpha (TNF-alpha) levels. DM also attenuated production of superoxide and intracellular reactive oxygen species in Kupffer cells and neutrophils. Real-time RT-PCR analysis revealed that DM administration suppressed the expression of a variety of inflammation-related genes such as macrophage inflammatory protein-2, CXC chemokine, thrombospondin-1, intercellular adhesion molecular-1 and interleukin-6. DM also decreased the expression of genes related to cell-death pathways, such as the DNA damage protein genes GADD45 and GADD153. In summary, DM is effective in protecting mice against LPS/GalN-induced hepatotoxicity, and the mechanism is likely through a faster TNF-alpha clearance, and decrease of superoxide production and inflammation and cell-death related components. This study not only extends neuroprotective effect of DM, but also suggests that DM may be a novel compound for the therapeutic intervention for sepsis. /The

Pharmacodynamics

Dextromethorphan is an opioid-like molecule indicated in combination with other medication in the treatment of coughs and pseudobulbar affect. It has a moderate therapeutic window, as intoxication can occur at higher doses. Dextromethorphan has a moderate duration of action. Patients should be counselled regarding the risk of intoxication.