Tydox Water Soluble Powder (Each gram contains Doxycycline hyclate BP equivalent to Doxycycline 100mg/Tylasin Tartrate BP 100mg)

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

• Motion sickness
• Nausea and vomiting
• Gastrointestinal spasms
• Preoperative sedation

Dosage

Children: Refer to the BNF for Children for specific dosing recommendations based on the child's age, weight, and condition being treated.

Adults: Refer to the appropriate clinical guidelines or BNF for specific dosing recommendations based on the condition being treated and patient factors.

Mechanism of action

Hyclate exerts its effects by antagonizing muscarinic acetylcholine receptors, which are found throughout the central and peripheral nervous systems. This inhibition leads to a decrease in acetylcholine-induced effects, particularly in the gastrointestinal system and vestibular apparatus, thus alleviating symptoms of nausea and motion sickness.

Pharmacodynamics

The pharmacodynamic effects of hyoscine include reduced gastrointestinal motility, decreased secretions, and a sedative effect on the central nervous system. Its antimuscarinic activity can result in side effects such as dry mouth, blurred vision, constipation, and drowsiness, depending on the dose and individual patient response.

Pharmacokinetics

Hyclate is well-absorbed from the gastrointestinal tract, and its peak plasma concentrations are typically reached within 2 hours after oral administration. The drug is widely distributed throughout the body, including the central nervous system where it crosses the blood-brain barrier. Hyoscine is metabolized in the liver and excreted primarily through the urine. The half-life of hyoscine is approximately 3 to 5 hours, but this can vary based on the formulation and route of administration.

Contra-indications

• Hypersensitivity to hyoscyamine or any of the excipients
• Glaucoma
• Myasthenia gravis
• Severe ulcerative colitis
• Tachycardia

Adverse effects

• Dry mouth
• Blurred vision
• Constipation
• Urinary retention
• Dizziness
• Confusion
• Nausea
• Vomiting

Interactions

• Anticholinergic agents may enhance effects
• Opioids may increase risk of constipation
• Antidepressants may increase anticholinergic effects
• Antihistamines may have additive sedative effects

Precautions

• Use with caution in patients with prostate enlargement
• May exacerbate conditions like heart disease or hypertension
• Caution in elderly patients due to increased sensitivity

Pregnancy

Consult the prescribing information; safety during pregnancy is not established.

Breast-feeding

Consult a healthcare provider; may inhibit lactation.

Storage

Store at room temperature, away from moisture and heat.

Formulations

• Oral tablets
• Injection solution
• Extended-release capsules

Indications

• Bacterial infections in livestock
• Mycoplasma infections
• Chlamydia infections
• Respiratory tract infections in animals

Dosage

Children: Refer to veterinary guidelines for specific dosages based on the condition being treated and the animal species involved.

Adults: Refer to veterinary guidelines for specific dosages based on the condition being treated and the animal species involved.

Mechanism of action

Tylasin binds to the 50S ribosomal subunit of bacteria, inhibiting protein synthesis by interfering with the translocation process during translation. This action ultimately prevents the growth and multiplication of susceptible bacteria.

Pharmacodynamics

As a macrolide antibiotic, tylasin exhibits bacteriostatic activity against Gram-positive organisms and some Gram-negative pathogens. Its spectrum of activity includes various strains of Mycoplasma, Chlamydia, and certain strains of Streptococcus and Staphylococcus. The drug's efficacy is enhanced in environments with high concentrations of the drug, as it can accumulate in tissues and exert prolonged effects.

Pharmacokinetics

Tylasin is administered via injection or oral route, and it is well absorbed in the gastrointestinal tract. After administration, it is distributed widely in body tissues and fluids, with a significant volume of distribution. Metabolism occurs primarily in the liver, and it is excreted mainly in bile and feces, with a lesser amount in urine. The half-life of tylasin varies depending on the species and route of administration.

Adverse effects

• Gastrointestinal disturbances
• Anaphylactic reactions
• Liver toxicity
• Hypersensitivity reactions

Interactions

• May interact with other antibiotics, leading to altered efficacy
• Potential interaction with anticoagulants

Precautions

• Use with caution in patients with liver disease
• Monitor for signs of allergic reactions
• Not recommended for use in pregnant animals without veterinary advice

Pregnancy

Tylosin is not recommended during pregnancy due to potential risks; consult a veterinarian.

Breast-feeding

Caution is advised as tylosin may be excreted in milk; consult a veterinarian.

Storage

Store in a cool, dry place away from light.

Formulations

• Oral powder
• Injectable solution
• Granules for oral suspension