GYNOFAST VAGINAL SUPPOSITORY

Indications

• Bacterial infections
• Skin and soft tissue infections
• Respiratory tract infections
• Bone and joint infections
• Dental infections
• Acne vulgaris (topical use)
• Intra-abdominal infections

Dosage

Adults: Refer to BNF for specific dosing recommendations based on the type and severity of the infection. Dosage may vary

Mechanism of action

Clindamycin inhibits bacterial protein synthesis by binding to the 23S RNA of the 50S subunit of the bacterial ribosome. This binding impedes both the assembly of the ribosome and the translation process. Clindamycin acts as a structural analog of tRNA molecules, impairing peptide chain initiation and stimulating the dissociation of peptidyl-tRNA from bacterial ribosomes. Its action may be bacteriostatic or bactericidal, depending on the concentration achieved at the infection site and the susceptibility of the pathogen.

Pharmacodynamics

Clindamycin exerts its bacteriostatic effect through the inhibition of microbial protein synthesis. It has a relatively short time to maximum concentration (Tmax) and half-life, necessitating frequent dosing to maintain adequate antibiotic levels. Clindamycin is associated with the risk of Clostridium difficile-associated diarrhea (CDAD), which can range from mild diarrhea to severe colitis. This side effect is due to the disruption of normal gut flora and the overgrowth of C. difficile, leading to toxin production.

Pharmacokinetics

Clindamycin is well absorbed when taken orally, with a bioavailability of approximately 90%. It distributes widely in body tissues and fluids, including bone. The drug undergoes hepatic metabolism, primarily via cytochrome P450 enzymes, and is excreted in urine as both unchanged drug and metabolites. The elimination half-life is approximately 2 to 3 hours, and renal impairment may affect its clearance.

Contra-indications

• Hypersensitivity to clindamycin or lincomycin
• History of antibiotic-associated colitis
• Use in patients with significant gastrointestinal disorders

Adverse effects

• Diarrhea
• Nausea
• Vomiting
• Rash
• Abdominal pain
• Clostridium difficile-associated diarrhea (CDAD)
• Hepatotoxicity
• Allergic reactions

Interactions

• Clindamycin may enhance the effects of neuromuscular blocking drugs
• Clindamycin may interact with other antibiotics leading to altered susceptibility patterns

Precautions

• Use with caution in patients with renal impairment
• Monitor for signs of colitis
• Assess liver function prior to therapy
• Avoid use in patients with a history of significant gastrointestinal disease

Pregnancy

Clindamycin is classified as category B. Animal studies have not demonstrated a risk to the fetus, but there are no adequate and well-controlled studies in pregnant women.

Breast-feeding

Clindamycin is excreted in breast milk, but significant absorption by the infant is unlikely. Caution is advised.

Storage

Store in a cool, dry place away from light. Reconstituted solutions should be stored in accordance with manufacturer guidelines and used within the specified time frame.

Formulations

• Oral capsules
• Oral suspension
• Solution for injection
• Topical solution and gel

Indications

• Vaginal candidiasis
• Vulval candidiasis
• Superficial fungal infections
• Otitis externa (as part of combination therapy)

Dosage

Adults: For vaginal candidiasis, 1 pessary of 500 mg can be inserted at night. Alternatively, for treatment with 1% cream, apply 2–3 times a day to the affected area for at least 14 days. For recurrent vulvovaginal candidiasis

Mechanism of action

Clotrimazole acts primarily by damaging the permeability barrier in the cell membrane of fungi. It inhibits ergosterol biosynthesis, which is essential for maintaining the integrity of fungal cell membranes. The inhibition of lanosterol 14-demethylase (CYP51) is a key mechanism behind its antifungal properties, leading to decreased ergosterol synthesis and resulting in cell membrane dysfunction. Clotrimazole also affects calcium homeostasis by inhibiting sarcoplasmic reticulum Ca2+-ATPase and blocking calcium-dependent potassium channels, contributing to its overall pharmacological effects.

Pharmacodynamics

Clotrimazole is considered a broad-spectrum antifungal that alters the permeability of fungal cell membranes, leading to inhibition of growth in pathogenic yeasts. At lower concentrations, it exhibits fungistatic properties, while at higher concentrations, it may be fungicidal against certain strains like Candida albicans. However, resistance to clotrimazole has become more common in recent years, limiting its efficacy in some populations.

Pharmacokinetics

Clotrimazole is primarily applied topically, and its absorption varies depending on the formulation and site of application. Following topical administration, systemic absorption is minimal, thereby reducing the risk of systemic side effects. The drug is metabolized in the liver and excreted via urine and feces. The pharmacokinetics may differ based on the dosing regimen and specific formulation used.

Contra-indications

• Hypersensitivity to clotrimazole or any excipients in the formulation
• Not recommended if trying to conceive due to potential damage to latex condoms and diaphragms

Adverse effects

• Skin reactions
• Vaginal burning
• Angioedema

Interactions

• Clotrimazole may increase the exposure of lomitapide, though the specific nature of this interaction is unknown

Precautions

• Avoid use in pregnancy without medical advice
• Use caution in patients with a history of hypersensitivity reactions

Pregnancy

Clotrimazole should be used during pregnancy only if clearly needed. Oral antifungal treatments should be avoided.

Breast-feeding

Clotrimazole is excreted in breast milk; caution is advised when used in breastfeeding mothers.

Storage

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

Formulations

• Clotrimazole 1% cream
• Clotrimazole 2% cream
• Clotrimazole 500 mg vaginal pessaries
• Clotrimazole 10% vaginal cream
• Clotrimazole 1% solution (ear drops)

Mechanism of action

Clindamycin inhibits bacterial protein synthesis by binding to 23S RNA of the 50S subunit of the bacterial ribosome. It impedes both the assembly of the ribosome and the translation process. The molecular mechanism through which this occurs is thought to be due to clindamycin's three-dimensional structure, which closely resembles the 3'-ends of L-Pro-Met-tRNA and deacylated-tRNA during the peptide elongation cycle - in acting as a structural analog of these tRNA molecules, clindamycin impairs peptide chain initiation and may stimulate dissociation of peptidyl-tRNA from bacterial ribosomes. The mechanism through which topical clindamycin treats acne vulgaris is unclear, but may be related to its activity against _Propionibacterium acnes_, a bacteria that has been associated with acne. Clindamycin may be bacteriostatic or bactericidal in action, depending on the concentration of the drug attained at the site of infection and the susceptibility of the infecting organism. Clindamycin palmitate hydrochloride and clindamycin phosphate are inactive until hydrolyzed to free clindamycin. This hydrolysis occurs rapidly in vivo. Clindamycin appears to inhibit protein synthesis in susceptible organisms by binding to 50S ribosomal subunits; the primary effect is inhibition of peptide bond formation. The site of action appears to be the same as that of erythromycin, chloramphenicol, and lincomycin. Clindamycin binds exclusively to the 50S subunit of bacterial ribosomes and suppresses protein synthesis. ... Clindamycin is not a substrate for macrolide efflux pumps, and strains that are resistant to macrolides by this mechanism are susceptible to clindamycin.

Pharmacodynamics

Clindamycin exerts its bacteriostatic effect via inhibition of microbial protein synthesis. Clindamycin has a relatively short T_max and half-life necessitating administration every six hours to ensure adequate antibiotic concentrations. _Clostridium difficile_ associated diarrhea (CDAD) has been observed in patients using clindamycin, ranging in severity from mild diarrhea to fatal colitis and occasionally occurring over two months following cessation of antibiotic therapy. Overgrowth of _C. difficile_ resulting from antibiotic use, along with its production of A and B toxins, contributes to morbidity and mortality in these patients. Because of the associated risks, clindamycin should be reserved for serious infections for which the use of less toxic antimicrobial agents are inappropriate. Clindamycin is active against a number of gram-positive aerobic bacteria, as well as both gram-positive and gram-negative anaerobes. Resistance to clindamycin may develop, and is generally the result of base modification within the 23S ribosomal RNA. Cross-resistance between clindamycin and lincomycin is complete, and may also occur between clindamycin and macrolide antibiotics (e.g. [erythromycin]) due to similarities in their binding sites. As antimicrobial susceptibility patterns are geographically distinct, local antibiograms should be consulted to ensure adequate coverage of relevant pathogens prior to use.

Mechanism of action

Clotrimazole acts primarily by damaging the permeability barrier in the cell membrane of fungi. Clotrimazole causes inhibition of ergosterol biosynthesis, an essential constituent of fungal cell membranes. If ergosterol synthesis is either completely or partially inhibited, the cell is no longer able to construct an intact and functional cell membrane,. Because ergosterol directly promotes the growth of fungal cells in a hormone‐like fashion, rapid onset of the above events leads to dose-dependent inhibition of fungal growth. Though decreased ergosterol, due to the inhibition of lanosterol 14-demethylase (also known as _CYP51_) is accepted to be primarily responsible for the antimycotic properties of clotrimazole, this drug also shows other pharmacological effects. These include the inhibition of sarcoplasmic reticulum Ca2+‐ATPase, depletion of intracellular calcium, and blocking of calcium‐dependent potassium channels and voltage‐dependent calcium channels. The action of clotrimazole on these targets accounts for other effects of this drug that are separate from its antimycotic activities. Clotrimazole exerts its antifungal activity by altering cell membrane permeability, apparently by binding with phospholipids in the fungal cell membrane. In contrast to polyene antibiotics (eg, amphotericin B), the action of clotrimazole is less dependent on the sterol content of the cell membrane. As a result of alteration of permeability, the cell membrane is unable to function as a selective barrier, and potassium and other cellular constituents are lost.

Pharmacodynamics

Clotrimazole is a broad-spectrum antifungal agent that inhibits the growth of pathogenic yeasts by changing the permeability of cell membranes. The action of clotrimazole is fungistatic at concentrations of drug up to 20 mcg/mL and may be fungicidal _in vitro_ against Candida albicans and other species of the genus Candida at higher concentrations. Unfortunately, resistance to clotrimazole, which was rare in the past, is now common in various patient populations. Clotrimazole is generally considered to be a fungistatic, and not a fungicidal drug, although this contrast is not absolute, as clotrimazole shows fungicidal properties at higher concentrations.