DOXYKO 300 TABLETS

Indications

• Bacterial infections
• Acne
• Destructive (refractory) periodontal disease
• Exacerbations of chronic bronchitis
• Leptospirosis
• Chlamydia infections
• Rickettsial infections
• Mycoplasma infections
• Acute necrotising ulcerative gingivitis

Dosage

Children: For children aged 12–17 years, initially 200 mg daily in 1–2 divided doses for the

Adults: Initially 200 mg daily in 1–2 divided doses for the first day, then maintenance 100 mg daily.

Mechanism of action

Doxycycline exerts its antibacterial effects by binding to the 30S ribosomal subunit of bacterial ribosomes, inhibiting the binding of aminoacyl-tRNA to the mRNA-ribosome complex. This inhibition of protein synthesis is crucial for bacterial growth and is the primary mechanism by which doxycycline exhibits its antimicrobial activity. It also impacts cellular metabolism and has been associated with non-genotoxic carcinogenic effects.

Pharmacodynamics

Doxycycline has a broad spectrum of activity against Gram-positive, Gram-negative bacteria, and some protozoa. Its bacteriostatic action is particularly effective against certain resistant strains, including MRSA. The drug's efficacy may vary based on the sensitivity of the bacteria, and resistance can develop through various mechanisms, such as efflux pumps and ribosomal protection.

Pharmacokinetics

Doxycycline is well absorbed from the gastrointestinal tract, with peak plasma concentrations typically reached within 2 hours after oral administration. It has a high volume of distribution and is approximately 90% protein-bound. The drug is metabolized in the liver and excreted primarily in feces, with a smaller fraction eliminated in urine. The half-life of doxycycline is approximately 18 to 22 hours, allowing for once or twice daily dosing in most cases.

Contra-indications

• Pregnancy
• Breastfeeding
• Hypersensitivity to doxycycline or other tetracyclines
• Myasthenia gravis
• Severe hepatic impairment

Adverse effects

• Photosensitivity
• Dizziness
• Headache
• Nausea
• Vomiting
• Diarrhoea
• Angioedema
• Skin reactions
• Pseudomembranous enterocolitis
• Tooth discolouration
• Intracranial hypertension
• Thrombocytopenia
• Stevens-Johnson syndrome
• Pancreatitis

Interactions

• Fosphenytoin (decreases concentration)
• Rifampicin (decreases exposure)
• Ciclosporin (unknown effect on concentration)
• Antacids containing aluminium or magnesium (reduce absorption)
• Iron supplements (reduce absorption)
• Warfarin (may enhance anticoagulant effect)

Precautions

• Use with caution in renal impairment
• May cause increased intracranial pressure
• Risk of superinfection (e.g., fungal infections)
• Avoid exposure to sunlight or sun lamps
• Monitor liver function in patients receiving prolonged therapy

Pregnancy

Should not be given to pregnant women; effects on skeletal development have been documented in the first trimester in animal studies. Administration during the second or third trimester may cause discoloration of the child's teeth, and maternal hepatotoxicity has been reported with large parenteral doses.

Breast-feeding

Should not be given to women who are breastfeeding; absorption may lead to discoloration of teeth in the infant.

Storage

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

Formulations

• Tablets
• Capsules
• Oral suspension
• Oral solution

Indications

• Bladder cancer
• Tuberculosis vaccination

Dosage

Children: Refer to the BNF for Children for appropriate dosing based on indication.

Adults: Refer to specific guidelines based on indication. For bladder cancer, a common regimen is instillation once a week for six weeks.

Mechanism of action

BCG works by stimulating the immune system, particularly through the activation of T-cells and macrophages. It enhances the immune response against tumor cells and Mycobacterium tuberculosis, promoting the release of cytokines and other immune mediators that contribute to the destruction of cancerous cells and pathogens.

Pharmacodynamics

The pharmacodynamics of BCG involve the induction of a robust immune response characterized by the activation of both innate and adaptive immunity. This includes the proliferation of T-lymphocytes and the production of cytokines such as tumor necrosis factor-alpha (TNF-alpha) and interleukins, leading to increased immune surveillance and anti-tumor activity. The effectiveness of BCG is influenced by factors such as the host's immune status and the presence of any concurrent infections.

Pharmacokinetics

BCG is administered locally, and its pharmacokinetics are determined by the route of administration. After intravesical administration, BCG remains in the bladder and exerts its effects locally, with minimal systemic absorption. The half-life and clearance of BCG can vary based on the patient's immune response and presence of any concurrent conditions.

Interactions

• normal immunoglobulin + bacillus calmette-gurin vaccine: Unknown (decreases efficacy)

Pregnancy

Bacillus Calmette-Guérin (BCG) vaccine can be administered during pregnancy if the potential benefit outweighs the potential risk.

Breast-feeding

BCG vaccine may be administered during breastfeeding; however, caution is advised.

Storage

Store at 2-8 degrees Celsius. Do not freeze.

Formulations

• Bacillus Calmette-Guérin vaccine

Indications

• Metabolic acidosis
• Lactic acidosis
• Support in shock or severe dehydration
• Exercise physiology research

Dosage

Children: Refer to clinical guidelines for specific dosing recommendations based on the clinical condition being treated.

Adults: Refer to clinical guidelines for specific dosing recommendations based on the clinical condition being treated.

Mechanism of action

Lactic acid primarily functions by contributing to the acid-base balance in the body. It can serve as a substrate for gluconeogenesis in the liver and is utilized in the Cori cycle, where it is converted back to glucose. Furthermore, lactic acid can act as a signaling molecule in various physiological processes, influencing metabolism and cellular responses during hypoxic conditions.

Pharmacodynamics

Lactic acid dissociates into lactate and hydrogen ions in solution, which can lead to a decrease in pH (acidosis) when produced in excess. Its accumulation in the body is indicative of anaerobic metabolism, often observed during intense exercise or in conditions of oxygen deprivation. The body can buffer the effects of lactic acid through bicarbonate and other mechanisms, maintaining homeostasis.

Pharmacokinetics

Lactic acid is rapidly absorbed and distributed throughout the body. It is metabolized primarily in the liver, where it can be converted to glucose or further metabolized to carbon dioxide and water. The elimination half-life of lactate varies depending on the metabolic state of the individual and the presence of underlying conditions. Renal function also plays a role in the clearance of lactate from the body.

Adverse effects

• Nausea
• Vomiting
• Abdominal pain
• Diarrhea
• Hypersensitivity reactions

Precautions

• Use with caution in patients with renal impairment
• Monitor for signs of metabolic acidosis
• Caution in patients with liver disease

Pregnancy

Lactic acid is generally regarded as safe, but clinical use should be evaluated on a case-by-case basis during pregnancy.

Breast-feeding

Considered safe for use during breastfeeding, but consult healthcare provider for individual cases.

Storage

Store at room temperature, away from direct sunlight and moisture.

Formulations

• Lactic acid injection
• Lactic acid oral solution