Betavard cream

Indications

• Suppression of inflammatory disorders
• Management of allergic conditions
• Congenital adrenal hyperplasia
• Inflammatory and allergic eye conditions

Dosage

Children: For children aged 1–11 months: Initially 1 mg, repeated up to 4 times in 24 hours according to response. Aged 1–5 years: Initially 2 mg, repeated up to 4 times in 24 hours according to response. Aged 6–11 years: Initially 4 mg, repeated up to 4 times in 24 hours according to response. Aged 12–17 years: 4–20 mg, repeated up to 4 times in 24 hours according to response.

Adults: Dosage varies based on condition; typically, initial doses are adjusted according to the patient's response and severity of condition.

Mechanism of action

Betamethasone exerts its effects by binding to glucocorticoid receptors, leading to modulation of gene expression and suppression of inflammatory cytokines and mediators.

Pharmacodynamics

Betamethasone reduces inflammation and immune response, which is beneficial in managing various inflammatory and allergic disorders.

Pharmacokinetics

Betamethasone is rapidly absorbed after administration, with a long half-life allowing for once-daily dosing in many cases. It is metabolized in the liver and excreted primarily in urine.

Adverse effects

• Hiccups
• Oedema
• Mood and behaviour changes
• Vision disorders
• Serious gastro-intestinal effects
• Musculoskeletal effects
• Ophthalmic effects
• Stevens-Johnson syndrome
• Myocardial rupture (following recent myocardial infarction)

Interactions

• Cobicistat + betamethasone: Unknown (increases exposure)
• Idelalisib + betamethasone: Unknown (increases exposure)
• Clarithromycin + betamethasone: Unknown (increases exposure)

Precautions

• Immunosuppression due to prolonged corticosteroid treatment
• Adrenal suppression if given for longer than 3 weeks
• Increased susceptibility to infections, including chickenpox and measles

Pregnancy

Readily crosses the placenta. Transient effect on fetal movements and heart rate.

Storage

Store at room temperature, protect from light.

Formulations

• Betamethasone sodium phosphate 4 mg per 1 ml solution for injection ampoules

Indications

• Vaginal candidiasis
• Oropharyngeal candidiasis
• Vulvovaginal infections
• Superficial fungal infections

Dosage

Adults: For vaginal candidiasis, miconazole cream is typically applied twice daily, using 5 g inserted into the vagina for 7 days. For oropharyngeal candidiasis, the oral gel is usually administered as 2.5 mL four times a day.

Mechanism of action

Miconazole primarily acts through the inhibition of the CYP450 14α-lanosterol demethylase enzyme, leading to disrupted ergosterol production in fungal cell membranes. This disruption results in increased cell membrane permeability and leakage of essential cellular constituents. Additionally, miconazole inhibits fungal peroxidase and catalase, increasing the production of reactive oxygen species (ROS) which contribute to fungal cell death. Miconazole also elevates intracellular levels of farnesol, which disrupts quorum sensing in Candida, preventing the transition to more virulent forms.

Pharmacodynamics

Miconazole is predominantly applied topically, leading to minimal systemic absorption. Its primary adverse reactions are usually localized to hypersensitivity reactions, with the potential for anaphylaxis in rare cases. Patients using intravaginal miconazole are advised to avoid reliance on other contraceptive methods and not to use tampons simultaneously due to the risk of altered vaginal flora.

Pharmacokinetics

Miconazole is poorly absorbed when applied topically or intravaginally, resulting in low systemic exposure. The pharmacokinetics of miconazole can vary based on the route of administration, but systemic absorption is generally low, thus limiting systemic side effects and interactions. Miconazole is extensively metabolized in the liver, and its metabolites are excreted primarily through the urine.

Contra-indications

• Hypersensitivity to miconazole or any of its excipients
• Recent arterial thromboembolic disease (e.g. angina, myocardial infarction)
• Undiagnosed vaginal bleeding
• Oestrogen-dependent tumors (e.g. breast cancer in first-degree relatives)
• Acute porphyrias
• Severe diabetes (increased risk of heart disease)

Adverse effects

• Dysmenorrhoea
• Skin reactions
• Increased risk of gallbladder disease
• Migraine or migraine-like headaches
• Abdominal pain
• Dysuria
• Nausea
• Pelvic cramps
• Vaginal hemorrhage
• Angioedema

Interactions

• Miconazole + antihistamines (non-sedating): Severe (increases exposure)
• Miconazole + mizolastine: Severe (increases exposure)
• Miconazole + oral benzodiazepines: Severe (increases exposure)
• Miconazole + ergometrine: Severe (increases exposure)
• Miconazole + ergotamine: Severe (increases exposure)
• Miconazole + alkylating agents: Moderate (increases concentration)
• Miconazole + busulfan: Moderate (increases concentration)
• Miconazole + antiarrhythmics: Moderate (increases exposure)
• Miconazole + disopyramide: Moderate (increases exposure)
• Miconazole + benzodiazepines: Moderate (increases exposure)

Precautions

• Caution in patients with history of breast cancer
• Monitor breast status regularly in women on oestrogen therapy
• Risk of endometrial cancer with prolonged use of oestrogens
• Risk of ovarian cancer with long-term use of combined HRT
• Increased risk of venous thromboembolism in women using combined or oestrogen-only HRT

Pregnancy

Pregnant women may require a longer duration of treatment, usually about 7 days, to clear the infection. Caution is advised.

Breast-feeding

Manufacturer advises caution; no specific information available.

Indications

• Bacterial infections
• Sepsis
• Pneumonia
• Meningitis
• Endocarditis
• Biliary tract infections
• Prostatitis
• Surgical prophylaxis
• Acute diverticulitis
• Leg ulcer infections

Dosage

Adults: 3–5 mg/kg daily in 3 divided doses, or a single daily dose of 5–7 mg/kg adjusted according to serum-gentamicin concentration. For surgical prophylaxis, 1.5 mg/kg administered intraven

Mechanism of action

Gentamicin exerts its antibacterial effects through a multi-phase mechanism. Initially, it binds to negatively charged components of bacterial cell membranes, increasing membrane permeability. Following this, it enters the bacterial cell via energy-dependent transport mechanisms, where it binds to the 30S ribosomal subunit. This binding causes mistranslation of proteins and disrupts membrane integrity, resulting in bacterial cell death. The action is concentration-dependent, leading to rapid bactericidal effects.

Pharmacodynamics

Gentamicin has a rapid onset of action due to its mechanism of disrupting the bacterial cell membrane and inhibiting protein synthesis. Its effectiveness is enhanced by higher concentrations, and it demonstrates a post-antibiotic effect where bacteria remain suppressed even after drug levels fall below the minimum inhibitory concentration. The drug's efficacy is influenced by factors like the bacterial strain and its susceptibility patterns.

Pharmacokinetics

Gentamicin is usually administered intravenously or intramuscularly. It has a volume of distribution of approximately 0.25 L/kg and is not significantly protein-bound. The drug is primarily eliminated via renal excretion, with a half-life of 2 to 3 hours in individuals with normal renal function. Dosing adjustments are necessary in patients with renal impairment to avoid toxicity. Serum levels should be monitored to optimize therapeutic efficacy while minimizing toxicity.

Contra-indications

• Hypersensitivity to gentamicin or any aminoglycoside
• Severe renal impairment
• Pre-existing auditory or vestibular dysfunction

Adverse effects

• Ototoxicity (hearing loss, vertigo, tinnitus)
• Nephrotoxicity
• Neuromuscular blockade
• Allergic reactions (rash, pruritus)
• Injection site reactions

Interactions

• Gentamicin + relugolix: Unknown (increases exposure)
• Gentamicin + other nephrotoxic drugs (e.g., vancomycin, cisplatin): Increased risk of nephrotoxicity
• Gentamicin + neuromuscular blocking agents: Enhanced neuromuscular blockade

Precautions

• Monitor renal function during therapy, especially in patients with pre-existing renal impairment
• Caution in patients with pre-existing hearing loss or vestibular disorders
• Use with caution in pregnant women and during breastfeeding

Pregnancy

Use only if clearly needed and the benefit justifies the risk to the fetus. Limited data on use in pregnancy.

Breast-feeding

Gentamicin is excreted in breast milk, exercise caution when administering to breastfeeding mothers. Monitor infant for possible side effects.

Storage

Store below 25°C. Protect from light. Do not freeze.

Formulations

• Injection solution (various concentrations)
• Ophthalmic solution (0.3% w/v)
• Topical ointment (0.1% w/v)

Indications

• Eczema
• Psoriasis
• Contact dermatitis
• Seborrheic dermatitis
• Atopic dermatitis

Dosage

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

Adults: Refer to relevant clinical guidelines or product information for specific dosing instructions.

Mechanism of action

Betamethasone dipropionate exerts its effects by binding to the glucocorticoid receptor, leading to the modulation of gene expression. This interaction results in the inhibition of pro-inflammatory cytokines, chemokines, and adhesion molecules, which reduces inflammation, suppresses the immune response, and promotes vasoconstriction in the affected tissues.

Pharmacodynamics

The pharmacodynamic effects of betamethasone dipropionate include a significant reduction in inflammation and immune response due to the inhibition of leukocyte infiltration at the site of inflammation. The drug also inhibits the release of arachidonic acid, subsequently decreasing the production of inflammatory mediators such as prostaglandins and leukotrienes. Its efficacy is enhanced by its high lipid solubility, allowing for better penetration through the skin layers.

Pharmacokinetics

Betamethasone dipropionate is well absorbed through the skin when applied topically. Its bioavailability is influenced by the formulation and the condition of the skin. The drug is metabolized primarily in the liver to inactive metabolites, which are excreted in the urine. The systemic absorption and effects are minimal when used as directed, but caution is advised in extensive applications or occlusive dressings, which may increase absorption.

Adverse effects

• Local skin atrophy
• Striae
• Telangiectasia
• Hypopigmentation
• Allergic contact dermatitis
• Systemic effects with prolonged use

Precautions

• Use with caution in patients with a history of diabetes mellitus
• Monitor for potential adrenal suppression with prolonged use
• Avoid application to infected areas unless treated

Pregnancy

Betamethasone dipropionate should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Limited data suggest that topical corticosteroids have low systemic absorption.

Breast-feeding

Caution is advised when using betamethasone dipropionate during breastfeeding, as it is unknown whether it is excreted in breast milk. Topical corticosteroids should be applied sparingly and avoided on the breast area to minimize ingestion by the infant.

Storage

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

Formulations

• Topical cream
• Topical ointment
• Topical lotion

Mechanism of action

Glucocorticoids inhibit neutrophil apoptosis and demargination, and inhibit NF-Kappa B and other inflammatory transcription factors. They also inhibit phospholipase A2, leading to decreased formation of arachidonic acid derivatives. In addition, glucocorticoids promote anti-inflammatory genes like interleukin-10. Corticosteroids like betamethasone can act through nongenomic and genomic pathways. The genomic pathway is slower and occurs when glucocorticoids activate glucocorticoid receptors and initiate downstream effects that promote transcription of anti-inflammatory genes including phosphoenolpyruvate carboxykinase (PEPCK), IL-1-receptor antagonist, and tyrosine amino transferase (TAT). On the other hand, the nongenomic pathway is able to elicit a quicker response by modulating T-cell, platelet and monocyte activity through the use of existing membrane-bound receptors and second messengers. Corticosteroids interact with specific receptor proteins in target tissues to regulate the expression of corticosteroid responsive genes, thereby changing the levels and array of proteins synthesized by the various target tissues. As a consequence of the time required for changes in gene expression and protein synthesis, most effects of corticosteroids are not immediate, but become apparent after several hours. ... Although corticosteroids predominantly act to increase expression of target genes, there are well documented examples where glucocorticoids decrease transcription of target genes ... In contrast to these genomic effects, recent studies have raised the possibility that some actions of corticosteroids are immediate and are mediated by membrane-bound receptors. /Adrenocorticosteroids/ The mechanisms by which glucocorticoids inhibit glucose utilization in peripheral tissues are not fully understood. Glucocorticoids decrease glucose uptake in adipose tissue, skin, fibroblasts, thymocytes, and polymorphonuclear leukocytes; these effects are postulated to result from translocation of the glucose transporters from the plasma membrane to an intracellular location. These peripheral effects are associated with a number of catabolic actions, including atrophy of lymphoid tissue, decreased muscle mass, negative nitrogen balance, and thinning of the skin. /Adrenocorticalsteroids/ The mechanisms by which the glucocorticoids promote gluconeogenesis are not fully defined. Amino acids mobilized from a number of tissues in response to glucocorticoids reach the liver and provide substrate for the production of glucose and glycogen. In the liver, glucocorticoids induce the transcription of a number of enzymes involved in gluconeogenesis and amino acid metabolism, including phosphoenolpyruvate carboxykinase, glucose-6-phosphatase, and fructose-2,6-bisphosphatase. Analyses of the molecular basis for regulation of phosphoenolpyruvate carboxykinase gene expression have identified complex regulatory influences involving an interplay among glucocorticoids, insulin, glucagon, and catecholamine. The effects of these hormones and amines on phosphoenolpyruvate carboxykinase gene expression mirror the complex regulation of gluconeogenesis in the intact organism. /Adrenocorticalsteroids/ ... /A/ major action of corticosteroids on the cardiovascular system is to enhance vascular reactivity to other vasoactive substances. Hypoadrenalism generally is associated with hypotension and reduced response to vasoconstrictors such as norepinephrine and angiotensin II. This diminished pressor response is explained partly by recent studies in experimental systems showing that glucocorticoids increase expression of adrenergic receptors in the vascular wall. Conversely, hypertension is seen in patients with excessive glucocorticoid secretion, occurring in most patients with Cushing's syndrome and in a subset of patients treated with synthetic glucocorticoids (even those lacking any significant mineralocorticoid action). /Adrenocorticosteroids/ For more Mechanism of Action (

Pharmacodynamics

Corticosteroids bind to the glucocorticoid receptor inhibiting pro-inflammatory signals, while promoting anti-inflammatory signals. Corticosteroids have a wide therapeutic window as patients may require doses that are multiples of what the body naturally produces. Patients who require long-term treatment with a corticosteroid should be counselled regarding the risk of hypothalamic-pituitary-adrenal axis suppression and increased susceptibility to infections.

Mechanism of action

There are 3 key phases of aminoglycoside entry into cells. The first “ionic binding phase” occurs when polycationic aminoglycosides bind electrostatically to negatively charged components of bacterial cell membranes including with lipopolysaccharides and phospholipids within the outer membrane of Gram-negative bacteria and to teichoic acids and phospholipids within the cell membrane of Gram-positive bacteria. This binding results in displacement of divalent cations and increased membrane permeability, allowing for aminoglycoside entry. The second “energy-dependent phase I” of aminoglycoside entry into the cytoplasm relies on the proton-motive force and allows a limited amount of aminoglycoside access to its primary intracellular target - the bacterial 30S ribosome. This ultimately results in the mistranslation of proteins and disruption of the cytoplasmic membrane. Finally, in the “energy-dependent phase II” stage, concentration-dependent bacterial killing is observed. Aminoglycoside rapidly accumulates in the cell due to the damaged cytoplasmic membrane, and protein mistranslation and synthesis inhibition is amplified. The necessity of oxygen-dependent active transport explains why aminoglycosides are ineffective against anaerobic bacteria. Hence, aminoglycosides have both immediate bactericidal effects through membrane disruption and delayed bactericidal effects through impaired protein synthesis; observed experimental data and mathematical modeling support this two-mechanism model. Inhibition of protein synthesis is a key component of aminoglycoside efficacy. Structural and cell biological studies suggest that aminoglycosides bind to the 16S rRNA in helix 44 (h44), near the A site of the 30S ribosomal subunit, altering interactions between h44 and h45. This binding also displaces two important residues, A1492 and A1493, from h44, mimicking normal conformational changes that occur with successful codon-anticodon pairing in the A site. Overall, aminoglycoside binding has several negative effects including inhibition of translation, initiation, elongation, and ribosome recycling. Recent evidence suggests that the latter effect is due to a cryptic second binding site situated in h69 of the 23S rRNA of the 50S ribosomal subunit. Also, by stabilizing a conformation that mimics correct codon-anticodon pairing, aminoglycosides promote error-prone translation. Mistranslated proteins can incorporate into the cell membrane, inducing the damage discussed above. Aminoglycosides are usually bactericidal in action. Although the exact mechanism of action has not been fully elucidated, the drugs appear to inhibit protein synthesis in susceptible bacteria by irreversibly binding to 30S ribosomal subunits. /Aminoglycosides/ ... Aminoglycosides are aminocyclitols that kill bacteria by inhibiting protein synthesis as they bind to the 16S rRNA and by disrupting the integrity of bacterial cell membrane. Aminoglycoside resistance mechanisms include: (a) the deactivation of aminoglycosides by N-acetylation, adenylylation or O-phosphorylation, (b) the reduction of the intracellular concentration of aminoglycosides by changes in outer membrane permeability, decreased inner membrane transport, active efflux, and drug trapping, (c) the alteration of the 30S ribosomal subunit target by mutation, and (d) methylation of the aminoglycoside binding site. ... /Aminoglycosides/

Mechanism of action

Miconazole is an azole antifungal used to treat a variety of conditions, including those caused by _Candida_ overgrowth. Unique among the azoles, miconazole is thought to act through three main mechanisms. The primary mechanism of action is through inhibition of the CYP450 14α-lanosterol demethylase enzyme, which results in altered ergosterol production and impaired cell membrane composition and permeability, which in turn leads to cation, phosphate, and low molecular weight protein leakage. In addition, miconazole inhibits fungal peroxidase and catalase while not affecting NADH oxidase activity, leading to increased production of reactive oxygen species (ROS). Increased intracellular ROS leads to downstream pleiotropic effects and eventual apoptosis. Lastly, likely as a result of lanosterol demethylation inhibition, miconazole causes a rise in intracellular levels of farnesol. This molecule participates in quorum sensing in _Candida_, preventing the transition from yeast to mycelial forms and thereby the formation of biofilms, which are more resistant to antibiotics. In addition, farnesol is an inhibitor of drug efflux ABC transporters, namely _Candida_ CaCdr1p and CaCdr2p, which may additionally contribute to increased effectiveness of azole drugs.

Pharmacodynamics

Miconazole is an azole antifungal that functions primarily through inhibition of a specific demethylase within the CYP450 complex. As miconazole is typically applied topically and is minimally absorbed into the systemic circulation following application, the majority of patient reactions are limited to hypersensitivity and cases of anaphylaxis. Patients using intravaginal miconazole products are advised not to rely on contraceptives to prevent pregnancy and sexually transmitted infections, as well as not to use tampons concurrently.