X-Beta N Eye/Ear/Nasal Drops

Indications

• Suppression of inflammatory disorders
• Management of allergic conditions
• Congenital adrenal hyperplasia
• Inflammatory and allergic eye conditions

Dosage

Children: For children aged 1–11 months: Initially 1 mg, repeated up to 4 times in 24 hours according to response. Aged 1–5 years: Initially 2 mg, repeated up to 4 times in 24 hours according to response. Aged 6–11 years: Initially 4 mg, repeated up to 4 times in 24 hours according to response. Aged 12–17 years: 4–20 mg, repeated up to 4 times in 24 hours according to response.

Adults: Dosage varies based on condition; typically, initial doses are adjusted according to the patient's response and severity of condition.

Mechanism of action

Betamethasone exerts its effects by binding to glucocorticoid receptors, leading to modulation of gene expression and suppression of inflammatory cytokines and mediators.

Pharmacodynamics

Betamethasone reduces inflammation and immune response, which is beneficial in managing various inflammatory and allergic disorders.

Pharmacokinetics

Betamethasone is rapidly absorbed after administration, with a long half-life allowing for once-daily dosing in many cases. It is metabolized in the liver and excreted primarily in urine.

Adverse effects

• Hiccups
• Oedema
• Mood and behaviour changes
• Vision disorders
• Serious gastro-intestinal effects
• Musculoskeletal effects
• Ophthalmic effects
• Stevens-Johnson syndrome
• Myocardial rupture (following recent myocardial infarction)

Interactions

• Cobicistat + betamethasone: Unknown (increases exposure)
• Idelalisib + betamethasone: Unknown (increases exposure)
• Clarithromycin + betamethasone: Unknown (increases exposure)

Precautions

• Immunosuppression due to prolonged corticosteroid treatment
• Adrenal suppression if given for longer than 3 weeks
• Increased susceptibility to infections, including chickenpox and measles

Pregnancy

Readily crosses the placenta. Transient effect on fetal movements and heart rate.

Storage

Store at room temperature, protect from light.

Formulations

• Betamethasone sodium phosphate 4 mg per 1 ml solution for injection ampoules

Indications

• Bowel sterilization before surgery
• Hepatic coma
• Topical infections caused by susceptible organisms

Dosage

Children: Refer to the BNF for Children for appropriate dosing information.

Adults: By mouth: 1 g every 1 hour for 4 hours, then 1 g every 4 hours for 2–3 days. For hepatic coma: Up to 4 g daily in divided doses usually for 5–7 days.

Mechanism of action

Neomycin sulfate binds to the 30S ribosomal subunit of bacteria, leading to the misreading of mRNA and the inhibition of protein synthesis. This disrupts the production of essential proteins needed for bacterial growth and function, ultimately resulting in cell death.

Pharmacodynamics

Neomycin demonstrates bactericidal activity against susceptible bacteria. Its efficacy is enhanced in alkaline environments, which is why it is often used in combination with other agents for surgical prophylaxis. The drug is primarily effective against a range of gram-negative organisms, including Escherichia coli and Klebsiella species, but also has some activity against gram-positive organisms.

Pharmacokinetics

Neomycin is poorly absorbed from the gastrointestinal tract, and its systemic absorption is minimal when administered orally. In cases of systemic use, such as intramuscular or intravenous administration, neomycin is distributed widely in the body but is primarily excreted unchanged in the urine. The elimination half-life varies but is generally around 2 to 3 hours in individuals with normal renal function. Monitoring of serum concentrations is essential to prevent toxicity, especially in patients with renal impairment.

Adverse effects

• neurotoxicity
• ototoxicity
• nephrotoxicity
• allergic reactions
• skin rashes
• hearing loss

Interactions

• other nephrotoxic drugs
• loop diuretics
• neuromuscular blocking agents

Precautions

• monitor renal function
• use cautiously in patients with hearing impairment
• avoid concurrent use with other ototoxic medications
• ensure adequate hydration

Pregnancy

Safety in pregnancy has not been established. Use only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

Use caution; neomycin can be absorbed systemically and may affect the nursing infant.

Storage

Store at room temperature, away from light and moisture. Keep out of reach of children.

Formulations

• oral tablets
• topical ointments
• injectable solutions

Indications

• Eczema
• Psoriasis
• Contact dermatitis
• Seborrheic dermatitis
• Atopic dermatitis

Dosage

Children: Refer to the BNF for Children for appropriate dosing information.

Adults: Refer to relevant clinical guidelines or product information for specific dosing instructions.

Mechanism of action

Betamethasone dipropionate exerts its effects by binding to the glucocorticoid receptor, leading to the modulation of gene expression. This interaction results in the inhibition of pro-inflammatory cytokines, chemokines, and adhesion molecules, which reduces inflammation, suppresses the immune response, and promotes vasoconstriction in the affected tissues.

Pharmacodynamics

The pharmacodynamic effects of betamethasone dipropionate include a significant reduction in inflammation and immune response due to the inhibition of leukocyte infiltration at the site of inflammation. The drug also inhibits the release of arachidonic acid, subsequently decreasing the production of inflammatory mediators such as prostaglandins and leukotrienes. Its efficacy is enhanced by its high lipid solubility, allowing for better penetration through the skin layers.

Pharmacokinetics

Betamethasone dipropionate is well absorbed through the skin when applied topically. Its bioavailability is influenced by the formulation and the condition of the skin. The drug is metabolized primarily in the liver to inactive metabolites, which are excreted in the urine. The systemic absorption and effects are minimal when used as directed, but caution is advised in extensive applications or occlusive dressings, which may increase absorption.

Adverse effects

• Local skin atrophy
• Striae
• Telangiectasia
• Hypopigmentation
• Allergic contact dermatitis
• Systemic effects with prolonged use

Precautions

• Use with caution in patients with a history of diabetes mellitus
• Monitor for potential adrenal suppression with prolonged use
• Avoid application to infected areas unless treated

Pregnancy

Betamethasone dipropionate should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Limited data suggest that topical corticosteroids have low systemic absorption.

Breast-feeding

Caution is advised when using betamethasone dipropionate during breastfeeding, as it is unknown whether it is excreted in breast milk. Topical corticosteroids should be applied sparingly and avoided on the breast area to minimize ingestion by the infant.

Storage

Store at room temperature, away from light and moisture. Keep out of reach of children.

Formulations

• Topical cream
• Topical ointment
• Topical lotion

Indications

• Electrolyte replacement
• Volume expansion in hypovolemic patients
• Management of hyponatremia
• Support in intravenous fluid therapy

Dosage

Children: Refer to the BNF for Children for appropriate dosing in paediatric patients, as dosages may vary based on the formulation and clinical condition.

Adults: Refer to specific product information or clinical guidelines for dosage recommendations, as disodium is often part of combination products.

Mechanism of action

Disodium compounds often function by providing sodium ions that are essential for various physiological processes. Sodium ions play a critical role in maintaining osmotic balance, nerve impulse transmission, and muscle contraction. In the context of intravenous solutions, disodium helps to restore electrolyte balance in patients.

Pharmacodynamics

The pharmacodynamics of disodium is primarily related to its role in electrolyte balance and fluid homeostasis. Sodium ions are vital for the function of excitable tissues, including neurons and muscle cells. Changes in sodium levels can affect blood pressure, hydration status, and overall cellular function.

Pharmacokinetics

The pharmacokinetics of disodium compounds depend on their specific formulation and route of administration. When administered intravenously, disodium is rapidly distributed in the extracellular fluid, where it helps to maintain osmotic pressure. Sodium is primarily excreted by the kidneys, and its levels can be influenced by fluid intake, dietary sodium, and renal function.

Pregnancy

Use with caution. Consult a healthcare provider for specific guidance.

Breast-feeding

Use with caution. Consult a healthcare provider for specific guidance.

Storage

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

Indications

• Lead poisoning
• Mercury poisoning
• Calcium overload
• Certain diagnostic procedures involving heavy metals

Dosage

Children: Refer to the BNF for Children for appropriate dosing information tailored for paediatric patients.

Adults: Refer to the BNF for specific dosing guidelines based on the condition being treated, considering factors such as the severity of metal poisoning and renal function.

Mechanism of action

Edetate functions by forming stable complexes with divalent and trivalent metal ions, including lead and calcium, through its multiple carboxylate and amine groups. This chelation renders the metals more soluble and promotes their renal excretion, thereby reducing their toxic effects in the body.

Pharmacodynamics

The chelation of metals by edetate decreases the free metal concentration in the bloodstream, which mitigates the toxic effects associated with heavy metal accumulation. The efficacy of edetate in removing metals such as lead has been well documented, and its ability to bind calcium can influence calcium homeostasis in certain clinical scenarios.

Pharmacokinetics

Edetate is administered intravenously, with rapid distribution throughout the extracellular fluid. It is primarily excreted unchanged by the kidneys. The onset of action occurs quickly after administration, and the duration depends on the dose and the patient's renal function. The elimination half-life is approximately 1 hour but may vary based on renal clearance.

Contra-indications

• Hypersensitivity to edetate or any component of the formulation
• Severe renal impairment
• Active bleeding disorders

Adverse effects

• Hypocalcemia
• Nausea
• Vomiting
• Diarrhea
• Abdominal pain
• Headache
• Rash
• Fever

Interactions

• May enhance the effects of anticoagulants
• Concurrent use with calcium supplements may reduce effectiveness
• May interfere with the absorption of certain medications due to changes in gastrointestinal motility

Precautions

• Use with caution in patients with renal impairment
• Monitor electrolyte levels, particularly calcium, during treatment
• Assess the patient's hydration status before administration

Pregnancy

Limited data on the use of edetate in pregnancy. Use only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

Caution is advised as it is not known whether edetate is excreted in human milk. Weigh the risks and benefits before use.

Storage

Store in a cool, dry place, protected from light. Do not freeze.

Formulations

• Edetate disodium injection
• Edetate calcium disodium injection

Indications

• Bacterial infections caused by aerobic organisms
• Topical treatment of skin infections

Mechanism of action

Neomycin binds to specific proteins and 16S rRNA within the 30S ribosomal subunit of susceptible bacteria. This binding interferes with the decoding site, causing misreading of mRNA and leading to the incorporation of incorrect amino acids into polypeptides. As a result, nonfunctional or toxic peptides are produced, and polysomes are disrupted into nonfunctional monosomes. Neomycin's bactericidal action is characterized by its ability to irreversibly bind to the 30S ribosomal subunit, thereby inhibiting bacterial protein synthesis.

Pharmacodynamics

Neomycin is primarily active against aerobic bacteria and is not effective against fungi, viruses, or most anaerobic bacteria. It mediates its bactericidal effects by inhibiting protein synthesis, which suppresses bacterial growth and survival. Following oral administration, neomycin exhibits a duration of bactericidal activity lasting between 48 to 72 hours. It is particularly useful in treating infections caused by strains of E. coli and Klebsiella, and it also acts to reduce colonic bacterial populations in patients with hepatic coma.

Pharmacokinetics

Neomycin is poorly absorbed from the gastrointestinal tract when taken orally, which limits its systemic availability and enhances its utility in targeting colonic bacteria. It is generally not used parenterally due to its potential for nephrotoxicity and ototoxicity. The duration of action following oral administration can last from 48 to 72 hours, and it is primarily excreted unchanged in the urine. Caution should be exercised when using neomycin in patients with renal impairment, as the risk of toxicity increases.

Adverse effects

• Nephrotoxicity
• Ototoxicity
• Allergic reactions
• Diarrhea
• Nausea
• Vomiting

Interactions

• neomycin+digoxin: Unknown (decreases absorption)
• neomycin+sorafenib: Unknown (decreases exposure)

Precautions

• Use with caution in patients with renal impairment
• Monitor renal function during therapy
• Evaluate hearing function in long-term use

Pregnancy

Neomycin is classified as category D; it should be used only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

Neomycin is excreted in breast milk; caution should be exercised when administered to nursing mothers.

Storage

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

Formulations

• Topical ointment
• Cream
• Eye drops
• Oral tablets

Indications

• Preservative in vaccines
• Antibacterial agent
• Antifungal agent

Dosage

Children: Refer to the BNF for Children for specific dosage guidelines, especially in

Adults: Refer to specific product guidelines or the BNF for detailed dosage information, as thimerosal is primarily used as a preservative in vaccines rather than in therapeutic doses.

Mechanism of action

Thimerosal inhibits sulfhydryl-containing active sites of various enzymes and binds to sulfhydryl compounds, including glutathione and cysteine. It activates the InsP3 calcium channel on the endoplasmic reticulum, leading to the release of intracellular calcium and subsequent cellular functions dependent on calcium signaling. Ethylmercury, the metabolite of thimerosal, is lipophilic and can cross the blood-brain barrier, contributing to its biological effects.

Pharmacodynamics

Thimerosal exhibits antibacterial and antifungal properties, functioning as a preservative in vaccines. Its pharmacological effects are mediated through interactions with cellular thiols and modulation of calcium signaling pathways. The toxic effects of high doses of thimerosal, such as oxidative stress and apoptosis, have been observed in vitro, although the effects of low-dose exposure remain less understood.

Pharmacokinetics

Thimerosal is rapidly metabolized to ethylmercury, which is eliminated from the body more quickly than methylmercury. Ethylmercury has a shorter half-life, leading to limited accumulation and toxic potential when used in vaccine formulations. The octanol/water partition coefficients indicate that both organomercury compounds, including ethylmercury, can primarily exist within cells, allowing them to cross cellular membranes effectively.

Adverse effects

• Hypersensitivity reactions
• Local reactions at injection site
• Neurotoxic effects at high doses
• Possible kidney pathology with toxic quantities

Precautions

• Use with caution in individuals with known hypersensitivity to thimerosal or other mercury compounds
• Monitoring for adverse effects in patients receiving multiple vaccines containing thimerosal

Pregnancy

Thimerosal should be used in pregnant women only if clearly needed, as the effects on fetal development are not fully established.

Breast-feeding

Thimerosal is considered compatible with breastfeeding, but caution is advised due to potential mercury exposure.

Storage

Store in a cool, dry place away from light. Protect from freezing. Ensure proper disposal of any unused or expired vaccine containing thimerosal.

Formulations

• Thimerosal-containing vaccines (various formulations)

Mechanism of action

Glucocorticoids inhibit neutrophil apoptosis and demargination, and inhibit NF-Kappa B and other inflammatory transcription factors. They also inhibit phospholipase A2, leading to decreased formation of arachidonic acid derivatives. In addition, glucocorticoids promote anti-inflammatory genes like interleukin-10. Corticosteroids like betamethasone can act through nongenomic and genomic pathways. The genomic pathway is slower and occurs when glucocorticoids activate glucocorticoid receptors and initiate downstream effects that promote transcription of anti-inflammatory genes including phosphoenolpyruvate carboxykinase (PEPCK), IL-1-receptor antagonist, and tyrosine amino transferase (TAT). On the other hand, the nongenomic pathway is able to elicit a quicker response by modulating T-cell, platelet and monocyte activity through the use of existing membrane-bound receptors and second messengers. Corticosteroids interact with specific receptor proteins in target tissues to regulate the expression of corticosteroid responsive genes, thereby changing the levels and array of proteins synthesized by the various target tissues. As a consequence of the time required for changes in gene expression and protein synthesis, most effects of corticosteroids are not immediate, but become apparent after several hours. ... Although corticosteroids predominantly act to increase expression of target genes, there are well documented examples where glucocorticoids decrease transcription of target genes ... In contrast to these genomic effects, recent studies have raised the possibility that some actions of corticosteroids are immediate and are mediated by membrane-bound receptors. /Adrenocorticosteroids/ The mechanisms by which glucocorticoids inhibit glucose utilization in peripheral tissues are not fully understood. Glucocorticoids decrease glucose uptake in adipose tissue, skin, fibroblasts, thymocytes, and polymorphonuclear leukocytes; these effects are postulated to result from translocation of the glucose transporters from the plasma membrane to an intracellular location. These peripheral effects are associated with a number of catabolic actions, including atrophy of lymphoid tissue, decreased muscle mass, negative nitrogen balance, and thinning of the skin. /Adrenocorticalsteroids/ The mechanisms by which the glucocorticoids promote gluconeogenesis are not fully defined. Amino acids mobilized from a number of tissues in response to glucocorticoids reach the liver and provide substrate for the production of glucose and glycogen. In the liver, glucocorticoids induce the transcription of a number of enzymes involved in gluconeogenesis and amino acid metabolism, including phosphoenolpyruvate carboxykinase, glucose-6-phosphatase, and fructose-2,6-bisphosphatase. Analyses of the molecular basis for regulation of phosphoenolpyruvate carboxykinase gene expression have identified complex regulatory influences involving an interplay among glucocorticoids, insulin, glucagon, and catecholamine. The effects of these hormones and amines on phosphoenolpyruvate carboxykinase gene expression mirror the complex regulation of gluconeogenesis in the intact organism. /Adrenocorticalsteroids/ ... /A/ major action of corticosteroids on the cardiovascular system is to enhance vascular reactivity to other vasoactive substances. Hypoadrenalism generally is associated with hypotension and reduced response to vasoconstrictors such as norepinephrine and angiotensin II. This diminished pressor response is explained partly by recent studies in experimental systems showing that glucocorticoids increase expression of adrenergic receptors in the vascular wall. Conversely, hypertension is seen in patients with excessive glucocorticoid secretion, occurring in most patients with Cushing's syndrome and in a subset of patients treated with synthetic glucocorticoids (even those lacking any significant mineralocorticoid action). /Adrenocorticosteroids/ For more Mechanism of Action (

Pharmacodynamics

Corticosteroids bind to the glucocorticoid receptor inhibiting pro-inflammatory signals, while promoting anti-inflammatory signals. Corticosteroids have a wide therapeutic window as patients may require doses that are multiples of what the body naturally produces. Patients who require long-term treatment with a corticosteroid should be counselled regarding the risk of hypothalamic-pituitary-adrenal axis suppression and increased susceptibility to infections.

Mechanism of action

Framycetin binds to specific 30S-subunit proteins and 16S rRNA, four nucleotides of 16S rRNA and a single amino acid of protein S12. This interferes with decoding site in the vicinity of nucleotide 1400 in 16S rRNA of 30S subunit. This region interacts with the wobble base in the anticodon of tRNA. This leads to interference with the initiation complex, misreading of mRNA so incorrect amino acids are inserted into the polypeptide leading to nonfunctional or toxic peptides and the breakup of polysomes into nonfunctional monosomes. Like other aminoglycoside antibiotic drugs, neomycin inhibits bacterial ribosomes by binding to the 30S ribosomal subunit of susceptible bacteria and disrupting the translational machinery of bacterial protein synthesis. Bacterial translation is normally initiated by the mRNA binding to the 30S ribosomal subunit and subsequent binding with 50S subunit for elongation. Aminoglycosides are usually bactericidal in action. Although the exact mechanism of action has not been fully elucidated, the drugs appear to inhibit protein synthesis in susceptible bacteria by irreversibly binding to 30S ribosomal subunits. /Aminoglycosides/ A class of angiogenesis inhibitor has emerged from our mechanistic study of the action of angiogenin, a potent angiogenic factor. Neomycin, an aminoglycoside antibiotic, inhibits nuclear translocation of human angiogenin in human endothelial cells, an essential step for angiogenin-induced angiogenesis. The phospholipase C-inhibiting activity of neomycin appears to be involved, because U-73122, another phospholipase C inhibitor, has a similar effect. In contrast, genistein, oxophenylarsine, and staurosporine, inhibitors of tyrosine kinase, phosphotyrosine phosphatase, and protein kinase C, respectively, do not inhibit nuclear translocation of angiogenin. Neomycin inhibits angiogenin-induced proliferation of human endothelial cells in a dose-dependent manner. At 50 microM, neomycin abolishes angiogenin-induced proliferation but does not affect the basal level of proliferation and cell viability. Other aminoglycoside antibiotics, including gentamicin, streptomycin, kanamycin, amikacin, and paromomycin, have no effect on angiogenin-induced cell proliferation. Most importantly, neomycin completely inhibits angiogenin-induced angiogenesis in the chicken chorioallantoic membrane at a dose as low as 20 ng per egg. These results suggest that neomycin and its analogs are a class of agents that may be developed for anti-angiogenin therapy. ... Aminoglycosides are aminocyclitols that kill bacteria by inhibiting protein synthesis as they bind to the 16S rRNA and by disrupting the integrity of bacterial cell membrane. Aminoglycoside resistance mechanisms include: (a) the deactivation of aminoglycosides by N-acetylation, adenylylation or O-phosphorylation, (b) the reduction of the intracellular concentration of aminoglycosides by changes in outer membrane permeability, decreased inner membrane transport, active efflux, and drug trapping, (c) the alteration of the 30S ribosomal subunit target by mutation, and (d) methylation of the aminoglycoside binding site. ... /Aminoglycosides/

Pharmacodynamics

Framycetin is used for the treatment of bacterial eye infections such as conjunctivitis. Framycetin is an antibiotic. It is not active against fungi, viruses and most kinds of anaerobic bacteria. Framycetin works by binding to the bacterial 30S ribosomal subunit, causing misreading of t-RNA, leaving the bacterium unable to synthesize proteins vital to its growth. Framycetin is useful primarily in infections involving aerobic bacteria bacteria. Neomycin mediates its bactericidal action by inhibiting bacterial protein synthesis, thereby suppressing the growth and survival of susceptible bacteria. Following oral administration, the duration of bactericidal activity of neomycin ranged from 48 to 72 hours. By decreasing colonic bacteria that produce ammonia, neomycin was shown to be effective as an adjunctive therapy in hepatic coma to improve neurologic symptoms. Neomycin is active against both gram positive and gram negative organisms, including the major _E. coli_ species resident in the colon as well as the enteropathogenic forms of _E. coli_. It is also active against _Klebsiella_-_Enterobacter_ group. Resistant strains of _E. coli_, _Klebsiella_ and _Proteus spp_. may emerge from neomycin therapy. Neomycin has no antifungal activity and has some activity against some protozoa.

Mechanism of action

Although its mechanism of action is not fully understood, thimerosal inhibits sulfhydryl-containing active site of various enzymes and binds to sulfhydryl compounds, including glutathione, cysteine, and sulfhydryl groups of proteins. In addition, thimerosal activates the InsP3 calcium channel on the endoplasmic reticular membrane, thereby triggering the release of intracellular calcium resulting in a calcium-induced calcium-influx of extracellular calcium. Therefore, thimerosal may induce or inhibit various cellular functions that are dependent on the signaling of calcium. Ethylmercury is metabolized to inorganic mercury more rapidly than methylmercury. This difference in metabolism may account for kidney pathology that can result from toxic quantities. Also, whereas the increase in oxidative stress and induction of apoptosis observed in vitro with large doses (405 μg/L to 101 mg/L) of thimerosal may explain its damaging neurological effects. The effects of low-dose ethylmercury are not completely understood to date. It is known, however, that the shorter half-life of ethylmercury (the metabolite of thimerosal) allows for very limited opportunities of ethylmercury derived from thimerosal in vaccines. Ethylmercury is a lipophilic cation that is capable of crossing the blood-brain barrier. The octanol/water partition coefficients of methyl and ethylmercury are 1.4 to 1.8, at intracellular pH and [Cl−], therefore, both organomercury compounds will primarily exist as intracellular lipophilic cations. It has been demonstrated that lipophilic cations accumulate inside mitochondria, in a Nernstian fashion, driven by the steady state membrane potential. As the typical mitochondrial membrane potential of astrocytes and neurons is between 140–170 mV, one would expect the concentration of these organomercury compounds within mitochondria to be approximately 1000 times greater than the cytosolic concentration.

Pharmacodynamics

Thimerosal is an organomercurial compound and derivative of thiosalicyclic acid with antibacterial and antifungal properties. Thimerosal, which consists of approximately 50% mercury by weight, has been one of the most widely used preservatives in vaccines. It is metabolized/degraded to ethylmercury and thiosalicylate. Ethylmercury is an organomercurial that must be carefully distinguished from methylmercury, a closely related substance that has been the focus of many studies. Methylmercury is the type of mercury found in various species of fish. Experimental data demonstrates that the toxicokinetics of thimerosal (ethylmercury) is vastly different from that of methyl-mercury. Thus, methyl-mercury is not a suitable reference for assessing the risk from exposure to thimerosal-derived mercury. Prior to the recent initiative to reduce or eliminate thimerosal from childhood vaccines, the maximum cumulative exposure to mercury via routine childhood vaccinations during the first 6 months of life was 187.5 micrograms. In the most recently formulated vaccines, the maximum cumulative exposure during the first 6 months of life should now be less than 3 micrograms of mercury. Currently, thimerosal may still be used in the early stages of manufacturing of certain childhood vaccines, however, only a trace remains after a chemical purification process. Note that the dose above is indicated for children 1-6 months of age is applicable only in the United States, and other countries may have varying indications.