DOXAN CAPSULES

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

• Acid-base balance disorders
• pH adjustment in various medical solutions
• Chemical burns in controlled settings

Dosage

Children: Refer to specific clinical guidelines for appropriate dosing as it can vary based on the condition and clinical scenario.

Adults: Refer to specific clinical guidelines for appropriate dosing as it can vary based on the condition and clinical scenario.

Mechanism of action

The biological activity of hydrogen chloride is associated with its high solubility in water, where it dissociates almost completely. The hydrogen ion interacts with water molecules to form the hydronium ion, which acts as a proton donor with catalytic properties, allowing it to react with organic molecules. This interaction can lead to cellular injury and necrosis.

Pharmacodynamics

Hydrochloride exerts its effects primarily through the formation of hydronium ions, which lower the pH of the surrounding environment and can disrupt cellular processes. The acidic nature of this compound facilitates various chemical reactions that may affect cellular integrity and function.

Pharmacokinetics

As an acid, hydrochloride does not undergo traditional pharmacokinetic processes such as absorption, distribution, metabolism, and excretion in the same way as conventional drugs. Its effects are immediate upon exposure, as it dissociates in solution to exert its acidic properties.

Pregnancy

Hydrochloric acid is classified as category C, meaning risk cannot be ruled out. Use only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

It is not known whether hydrochloric acid is excreted in human milk. Caution should be exercised when administered to breastfeeding women.

Storage

Store in a cool, dry place, away from light and tightly sealed to prevent moisture absorption.

Mechanism of action

The biological activity of hydrogen chloride is associated with its high solubility in water i.e., 23 moles/L at 0 °C. ... The hydrogen chloride in water dissociates almost completely, with the hydrogen ion captured by the water molecules to form the hydronium ion. The hydronium ion becomes a donor of a proton that possesses catalytic properties and thus is capable of reacting with organic molecules. This may explain the ability of hydrogen chloride to induce cellular injury and necrosis.