TYLODOXI 20/20

Indications

• Acne vulgaris
• Chlamydia infections
• Community-acquired pneumonia
• Cholera
• Gonorrhea
• Malaria prophylaxis
• Respiratory tract infections
• Urinary tract infections
• Rickettsial infections
• Periodontal disease

Dosage

Children: Refer to the BNF for Children for appropriate dosing guidelines in paediatric patients.

Adults: Refer to the BNF for specific dosing recommendations based on the indication being treated.

Mechanism of action

Doxycycline exerts its antibacterial effect by inhibiting protein synthesis in bacteria. It binds reversibly to the 30S ribosomal subunit, preventing the attachment of aminoacyl-tRNA to the mRNA-ribosome complex, which halts the translation process and ultimately inhibits bacterial growth. This mechanism makes it effective against a variety of microorganisms, including those that are resistant to other antibiotics.

Pharmacodynamics

Doxycycline displays bacteriostatic activity, meaning it inhibits the growth and reproduction of bacteria rather than killing them outright. The drug has a long half-life, allowing for once or twice daily dosing in most cases. Resistance to doxycycline can occur through various mechanisms, including efflux pump activation and ribosomal protection, which may reduce its effectiveness over time.

Pharmacokinetics

Doxycycline is well-absorbed from the gastrointestinal tract, with bioavailability ranging from 90% to 100%. It is distributed widely throughout the body, including penetration into tissues and fluids, such as lung tissue and pleural fluid. The drug is primarily excreted unchanged in the urine, with a half-life of approximately 18 to 22 hours in healthy adults. Adjustments may be necessary in patients with renal impairment, although significant dose modifications are generally not required for patients with mild to moderate renal dysfunction.

Contra-indications

• Hypersensitivity to doxycycline or any of the tetracycline antibiotics
• Severe hepatic impairment
• Pregnancy (especially during the second and third trimesters)
• Children under 8 years of age due to the risk of teeth discoloration

Adverse effects

• Gastrointestinal disturbances (nausea, vomiting, diarrhea)
• Photosensitivity
• Esophageal irritation or ulceration
• Allergic reactions (rash, urticaria)
• Hepatotoxicity
• Intracranial hypertension

Interactions

• Antacids containing aluminum, calcium, or magnesium can reduce absorption
• Iron supplements may interfere with absorption
• Warfarin and other anticoagulants may have increased effects
• Hormonal contraceptives may be less effective

Precautions

• Use with caution in patients with renal impairment
• Monitor for signs of hepatotoxicity
• Consider the potential for photosensitivity and advise patients to avoid excessive sun exposure
• Assess for any history of esophageal disorders

Pregnancy

Doxycycline is generally contraindicated during pregnancy due to the risk of teratogenic effects and potential impact on fetal bone development.

Breast-feeding

Doxycycline is excreted in breast milk and may affect the nursing infant. Caution is advised, and its use should be limited unless deemed necessary.

Storage

Store at room temperature, away from moisture and heat. Protect from light.

Formulations

• Capsules
• Tablets
• Oral suspension
• Injectable 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

• Angina pectoris
• Hypertension
• Cardiovascular disorders

Dosage

Children: Refer to relevant clinical guidelines or product-specific dosing information, as paediatric dosing must be tailored to the individual child's condition and weight.

Adults: Refer to relevant clinical guidelines or product-specific dosing information, as adult dosing can vary based on specific clinical condition and formulation.

Mechanism of action

Tartrates function primarily by acting on the vascular smooth muscle, promoting vasodilation. This action is mediated through the inhibition of calcium channels, leading to reduced intracellular calcium levels, which in turn decreases vascular resistance and lowers blood pressure.

Pharmacodynamics

The pharmacodynamics of tatrate involves its effect on the cardiovascular system, particularly in reducing myocardial oxygen demand and improving oxygen delivery. By facilitating vasodilation, tatrate helps to alleviate symptoms of angina and manage hypertension, enhancing overall cardiac performance and reducing the risk of ischemic events.

Pharmacokinetics

Tatrate is typically well-absorbed from the gastrointestinal tract. It undergoes hepatic metabolism and is excreted primarily via the kidneys. The onset of action varies depending on the formulation, with peak plasma concentrations generally occurring within 1-3 hours after oral administration. The half-life of tatrate also varies, but it is generally considered suitable for once or twice daily dosing depending on clinical needs.

Pregnancy

There is limited data on the use of tatrate during pregnancy. It is advised to use caution and consult a healthcare provider.

Breast-feeding

Limited information is available regarding the excretion of tatrate in breast milk. Caution is suggested when administering to nursing mothers.

Storage

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

Indications

• Bacterial infections in livestock
• Respiratory infections
• Enteritis caused by various pathogens
• Mycoplasma infections

Dosage

Children: For paediatric dosing, refer to the BNF for Children for appropriate dosing information based on age and weight.

Adults: Refer to the BNF for specific dosing guidelines based on the condition being treated, as doses may vary.

Mechanism of action

Tylosin inhibits peptide bond formation by binding to the 50S ribosomal subunit of bacteria, blocking the aminoacyl-tRNA from entering the ribosome and thus halting protein synthesis. This inhibition acts as a slow-binding, slowly reversible process, and the interaction with the ribosome is characterized by a significant degree of irreversibility, which is crucial for its antibiotic properties.

Pharmacodynamics

Tylosin exhibits bacteriostatic activity, meaning it inhibits bacterial growth rather than directly killing bacteria. Its effectiveness is particularly notable against certain strains of bacteria that are resistant to other antibiotic classes. The irreversibility of its action on the ribosome contributes to its long-lasting effects against bacterial infections.

Pharmacokinetics

After administration, tylosin is absorbed and distributed throughout the body. It is metabolized in the liver and excreted primarily in the bile, with some renal excretion. The half-life of tylosin can vary based on the route of administration and the species being treated. It is important to monitor for potential accumulation in cases of renal impairment.

Pregnancy

There is insufficient data on the use of tylosin during pregnancy. It should only be used if the potential benefits outweigh the risks.

Breast-feeding

It is not known whether tylosin is excreted in human milk. Caution should be exercised when administering to nursing mothers.

Storage

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

Formulations

• Tylosin tartrate tablets
• Tylosin injectable solution
• Tylosin oral suspension

Mechanism of action

The inhibition of peptide bond formation by tylosin, a 16-membered ring macrolide, was studied in a model system derived from Escherichia coli. In this cell-free system, a peptide bond is formed between puromycin (acceptor substrate) and AcPhe-tRNA (donor substrate) bound at the P-site of poly(U)-programmed ribosomes. It is shown that tylosin inhibits puromycin reaction as a slow-binding, slowly reversible inhibitor. Detailed kinetic analysis reveals that tylosin (I) reacts rapidly with complex C, i.e., the AcPhe-tRNA. poly(U).70S ribosome complex, to form the encounter complex CI, which then undergoes a slow isomerization and is converted to a tight complex, CI, inactive toward puromycin. These events are described by the scheme C + I <==> (K(i)) CI <==> (k(4), k(5)) CI. The K(i), k(4), and k(5) values are equal to 3 microM, 1.5 min(-1), and 2.5 x 10(-3) min(-1), respectively. The extremely low value of k(5) implies that the inactivation of complex C by tylosin is almost irreversible. The irreversibility of the tylosin effect on peptide bond formation is significant for the interpretation of this antibiotic's therapeutic properties; it also renders the tylosin reaction a useful tool in the study of other macrolides failing to inhibit the puromycin reaction but competing with tylosin for common binding sites on the ribosome. Thus, the tylosin reaction, in conjunction with the puromycin reaction, was applied to investigate the erythromycin mode of action. It is shown that erythromycin (Er), like tylosin, interacts with complex C according to the kinetic scheme C + Er <==> (K(er)) CEr <==> (k(6), k(7)) C*Er and forms a tight complex, CEr, which remains active toward puromycin. The determination of K(er), k(6), and k(7) enables us to classify erythromycin as a slow-binding ligand of ribosomes