Masti-Clear

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Medically reviewed

Laura Arias

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Masti-Clear

Property Description
Active Ingredient Benzylpenicillin (Penicillin G)
Form Injectable Suspension (often long-acting depot)
Pharmacological Class beta-Lactam Antibiotic
General Purpose To eliminate susceptible bacterial infections
Origin Natural Penicillin

What Type of Medicine is Masti-Clear?

Masti-Clear is a pharmaceutical preparation whose active component is Benzylpenicillin, a clinically recognized agent classified as a beta-Lactam antibiotic and an Antibacterial Agent. This medicine is categorized as a natural penicillin, meaning its original structure is biologically derived, distinguishing it from later semi-synthetic compounds. It is characterized as an essential medicine, underscoring its established value in infectious disease therapy.

Unlike broad-spectrum antibiotics, Masti-Clear is a narrow-spectrum agent. This characteristic is a defining factor in its therapeutic positioning, as it is primarily used when the infecting organism is known to be highly susceptible to this specific molecule, allowing for a precise and targeted intervention.


What is the Composition and Form of Masti-Clear?

The medication is composed of the active substance, Benzylpenicillin, often stabilized as a poorly soluble salt such as Procaine Benzylpenicillin or Benzathine Benzylpenicillin. This specialized preparation is physically an injectable suspension administered via the parenteral or local route. The inclusion of the salt form and a suspension vehicle allows the medicine to function as a depot injection. This specialized formulation is designed for slow, sustained release into the system over a prolonged period, ensuring a continuous presence of the antibiotic.


What is the Primary Benefit of Benzylpenicillin?

The primary benefit of Benzylpenicillin is its ability to swiftly and completely eliminate susceptible bacteria through a bactericidal action, which halts the spread and escalation of infection. The medication's pharmacological profile reinforces the critical benefit of Benzylpenicillin in controlling the multiplication of sensitive organisms in the body. The drug's narrow-spectrum action offers a precise therapeutic intervention when the identity of the causative pathogen is established. The prolonged therapeutic efficacy provided by its long-acting depot formulation is a key benefit, ensuring reliable control of persistent infections caused by susceptible organisms.

Regulatory References

  1. Benzathine benzylpenicillin on WHO Essential Medicines List

What side effects are possible with Masti-Clear?

Possible Side Effects and Safety Information

The safety profile of Benzylpenicillin (Masti-Clear) is defined by officially documented adverse reactions, which are classified by frequency and the affected System-Organ Class (SOC) as per regulatory standards.


Adverse Reaction Classification

Classification Type Examples of Officially Listed Reactions
Common Effects Gastrointestinal disturbances (nausea, vomiting, diarrhea), and local reactions such as pain or inflammation at the injection site.
Uncommon Effects Pseudomembranous colitis (C. difficile-associated diarrhea), and some early signs of neurotoxicity.
Rare/Very Rare Serious hematologic disorders (e.g., hemolytic anemia, leukopenia), interstitial nephritis, hepatitis, and severe systemic allergic responses.

Serious Adverse Reactions and Safety Constraints

The most critical documented safety concerns are related to hypersensitivity and neurotoxicity. The most severe allergic reaction, though rare, is anaphylactic shock. Neurological effects, which can manifest as seizures, are officially documented, particularly when drug concentrations are high in the bloodstream.

Special Population Safety: Official regulatory labeling specifies that patients with renal impairment are at an increased risk of elevated systemic concentrations, which can heighten the potential for neurotoxicity and seizures.

Contraindication: The medicine is strictly contraindicated in any individual with a known history of hypersensitivity to penicillin or other antibiotics of the beta-lactam class. Hypersensitivity reactions may be immediate or delayed (e.g., serum sickness-like reactions).

Overdose and Emergency Response

Overdose and When to Seek Help

Masti-Clear (Benzylpenicillin) overdose information is based on officially documented regulatory findings, primarily focusing on effects involving the Central Nervous System (CNS) and the cardiovascular system.

Officially documented manifestations of overdose include signs of neurotoxicity, which may present as convulsions, myoclonus, agitation, and states of confusion or hallucinations. Severe outcomes, including status epilepticus and coma, have been reported in official labeling. A significant risk associated with massive doses is the development of severe electrolyte imbalance—specifically hyperkalaemia (high potassium)—which can lead to cardiac arrest. This risk of severe neurotoxicity is noted to be significantly increased in patients with severe renal impairment.

Mandated Emergency Action

Governmental regulatory guidance requires that individuals experiencing severe overdose signs must seek immediate medical attention. This urgent action is mandated for any sign of neurological distress, such as seizures or profound confusion.

Official Management Protocols

According to prescribing information, no specific antidote is known for Masti-Clear overdose. Management is based strictly on symptomatic and supportive treatment. This includes immediate discontinuation of the product, close monitoring of fluid and electrolyte balance, and the potential use of procedures like haemodialysis to assist drug clearance in severe cases.

Therapeutic Uses of Masti-Clear

What Masti-Clear Treats: Main Uses and Benefits

Masti-Clear (Benzylpenicillin) is a long-acting, targeted antibiotic that is generally used to address conditions presenting with systemic or localized discomfort caused by specific, susceptible bacteria. Its application is relevant across domains where additional symptomatic support is needed, focusing on targeted action against the cause to help ease the overall symptom burden. Its applications cover generalized infections, severe tissue infections, and specific bacterial diseases.


Therapeutic Applications and Benefits

This medicine is commonly used in addressing serious, acute infections of the bloodstream (septicaemia), heart lining (endocarditis), and brain/spinal cord membranes (meningitis). It is also commonly used in deep-seated tissue conditions like osteomyelitis and severe cellulitis, as well as for managing specific public health diseases such as syphilis and providing secondary prophylaxis against rheumatic fever.

Masti-Clear is applied in clinical settings that involve acute or unstable symptom patterns. It helps address symptom clusters that may become intense or disruptive, such as high fever and profound fatigue. By addressing the bacterial cause, the medication contributes to improved comfort during periods of heightened symptoms.

“The long-acting nature of this treatment assists in supporting a sense of stability when symptoms are prone to recurrence, offering assistance in managing the risk of severe, late-stage disease progression.”

Quick Fact: Relief for Systemic Discomfort The medicine is relevant for easing symptoms related to inflammatory or irritative states, assisting with the functional stability of patients experiencing heightened symptoms from a severe, susceptible bacterial infection.

Eligibility and Restrictions for Use

Who can and cannot use Masti-Clear?

Eligibility Scope

Category Official Regulatory Statement
Populations for whom use is contraindicated Absolute exclusion for patients with a known hypersensitivity to any penicillin or a history of severe immediate allergic reaction to any other β-lactam antibiotic (e.g., cephalosporin).
Age-related eligibility rules Adults and adolescents are generally eligible. Use in infants and neonates is established but restricted; extended dosing intervals are necessary due to reduced renal clearance. Use in the older adult population requires assessment of renal function.
Condition-specific eligibility rules Patients with impaired renal function require conditional use and close monitoring due to the risk of drug accumulation and potential neurotoxicity. Caution is advised for those with severe heart conditions due to the sodium content of certain formulations.
Pregnancy and lactation eligibility status Generally permitted for use during pregnancy and lactation. Official labeling advises use only when clearly needed, though it is not classified as a contraindication.

Eligibility Classifications (High-Level)

Category Official Regulatory Statement
Eligibility severity classification Absolute Contraindication is defined by β-Lactam hypersensitivity. All other populations fall under Conditional Use or Permitted Use with Caution.

Resulting Eligibility Structure

Official regulatory documents establish that non-eligibility is determined solely by allergy status. Use in all other specific populations—including those with reduced kidney function, very young or older age, and pregnant or breastfeeding individuals—is defined by conditional eligibility. This regulatory framework requires medical oversight to manage the risk associated with drug clearance and administration across varying physiological states.

What should I know about interactions with other medicines?

Masti-Clear (Benzylpenicillin) has documented interaction patterns based primarily on how the medicine is eliminated from the body. The official regulatory profile notes specific pharmacokinetic and pharmacodynamic concerns with co-administered substances.


Interactions with Medicinal Products

The co-administration of Probenecid is formally documented to reduce the renal tubular secretion of Masti-Clear. This pharmacokinetic interaction results in an officially recognized increase and prolongation of Masti-Clear plasma concentration, raising its systemic exposure.

Conversely, Masti-Clear is linked to altering the clearance of other medicines. Regulatory information states that Benzylpenicillin can reduce the clearance of Methotrexate, an interaction documented to increase the potential for methotrexate toxicity. This mechanism involves competitive inhibition of renal tubular secretion for methotrexate.

A pharmacodynamic caution is also noted. Official guidance advises against combining Masti-Clear with bacteriostatic antibiotics (such as tetracyclines). This is due to the potential for antagonism, where the bactericidal effect of Masti-Clear may be reduced. There are no specific medicinal products formally classified as contraindicated due to interaction risk alone.


Population and Product Considerations

Interaction risks are formally noted as being heightened in specific conditions. Due to the drug's primary dependence on renal function for elimination, patients with impaired renal function may experience a more significant risk of reduced clearance for both Masti-Clear and co-administered renally-eliminated agents. For the long-acting injectable suspension formulation of Masti-Clear, official prescribing information does not document any interaction constraints with food, alcohol, or herbal products.

Mechanism of Action

How Masti-Clear Works

Masti-Clear is a small molecule inhibitor. It targets the IKKbeta (IκB Kinase β) subunit, which is a key component of the NF-kB signaling pathway. Masti-Clear acts by allosterically binding to IKKβ.

This allosteric binding event blocks the normal function of IKKβ, specifically preventing the phosphorylation of the IκBα protein. Consequently, IκBα remains intact and associated with the p50/p65 dimer in the cytoplasm. This molecular state prevents the nuclear translocation of the NF-kB transcription factor, thus decreasing the pathway's activity.

The subsequent inhibition of NF-kB-mediated gene transcription reduces the cellular output of pro-inflammatory cytokines such as IL-6 and TNF-α. This action modulates the structural dynamics of the surrounding cellular environment.

Dosage and Administration Information

Administration Scope and Dosing Schedule

Masti-Clear is administered by intramammary infusion and is indicated for use in lactating dairy cattle to treat mastitis. The product is supplied in a single-dose syringe intended for local delivery into the udder.

Official Dosing Rules:

  • Dose: Infuse the contents of one (1) single-use syringe (10 mL) into the infected quarter.
  • Frequency: Treatment may be repeated at intervals of 12 hours.
  • Maximum: Do not administer more than three (3) consecutive doses.

Procedural Steps and Conditions

Strict adherence to the following sanitary procedure is required for administration to minimize the risk of introducing contamination:

  1. The infected quarter must be completely milked out before treatment is administered.
  2. The teat and udder should be thoroughly washed with warm water containing a suitable dairy disinfectant and then dried.
  3. The teat end must be wiped clean using the provided antiseptic wipe, with a separate pad used for each teat to be treated.
  4. The entire contents of the syringe must be infused into the teat canal.
  5. After infusion, gently massage the quarter and teat to facilitate distribution of the medication upward into the milk cistern.

Special Conditions:

  • Treated quarters must not be milked for at least six hours after treatment, but regular milking intervals should be resumed thereafter.
  • This product is specifically labeled for use in lactating cows.
  • This is a veterinary prescription drug, which must be used by or on the order of a licensed veterinarian.

Recent Clinical Evidence

Research Evidence / Overview of Studies for Masti-Clear

The research landscape for the active ingredient in Masti-Clear, Benzylpenicillin, spans many decades and is described in reports from international health and regulatory bodies. The research focuses on the measured clearance of susceptible bacteria in specific serious conditions.


Evidence for Use in Severe Systemic Infections (Septicaemia and Severe Pneumonia)

Studies exploring Benzylpenicillin for severe systemic infections, such as those that can lead to blood poisoning (septicaemia) or severe pneumonia, primarily consist of Randomized Controlled Trials (RCTs) and observational cohort studies. These studies have examined high-level outcomes such as survival/mortality and the monitored change in fever over time in the observed populations. Research has also monitored measurements of microbiological clearance as an outcome measure.

In this context, the research has included diverse populations such as critically ill adult patients and children with severe infections. Findings describe that the concentration of the drug in the body, known as its pharmacokinetics (PK), is observed to be highly variable in patients with underlying conditions or those in the intensive care setting.


Evidence for Use in Specific Public Health Diseases (Syphilis and Rheumatic Fever Prophylaxis)

The research base for these two conditions is long-standing and well-documented. For syphilis, studies primarily tracked serological cure, monitoring the reduction of specific antibody levels. For the secondary prophylaxis of rheumatic fever, the evidence comes from long-term observational cohort studies focused on preventing recurrence of the fever episodes and the progression of associated heart valve damage.

These studies consistently report patterns related to the sustained low incidence of recurrent rheumatic fever episodes when prophylaxis is maintained over years. Because Benzylpenicillin is a documented standard of care for these conditions, modern comparative evidence is lacking for many aspects against certain other antibiotic therapies.


What Remains Uncertain About Masti-Clear Research

Research, while extensive, contains limitations. One key area of uncertainty relates to the aforementioned pharmacokinetic variability in specific, highly vulnerable populations, such as critically ill or severely malnourished patients, where achieving the necessary drug concentration was challenging in some studies. Furthermore, while studies describe high-level group patterns of response, research provides context but not individual predictions, and findings for deep-seated tissue infections showed variability due to the heterogeneity of the infection sites studied.

Key Studies & References

  1. Guideline for the Diagnosis and Management of Infective Endocarditis

Frequently Asked Questions (FAQ)

Common questions about Masti-Clear (FAQ)

Q: Is it common to feel tired or dizzy after starting Masti-Clear?

Regulatory documents state that side effects of the active ingredient can include dizziness. Some reported adverse effects also include sleepiness or a feeling of unusual weakness. This type of reaction is documented in the official safety profile.

Q: What is the risk of Masti-Clear interacting with over-the-counter pain relievers?

Official product information documents specific interactions with certain prescription medicines, such as those that affect the kidneys. However, the label does not explicitly name or classify all common over-the-counter (OTC) pain relievers as interacting substances.

Q: Is Masti-Clear known to interact with blood pressure medications?

Regulatory labeling documents specific drug-drug interactions based on how the drug is cleared from the body. There is no explicit general warning or listing regarding all classes of blood pressure medications in the official product information.

Q: Are there specific age groups that cannot use Masti-Clear?

Official documents state that the only absolute reason for exclusion from use is a known allergy to penicillin or other related beta-lactam antibiotics. Eligibility is determined by allergy status and is managed conditionally across different ages.

Q: Is Masti-Clear appropriate for older adults (seniors)?

Use in older adults is generally possible, but regulatory information advises that a person's renal function (how well the kidneys work) must be carefully assessed. Because drug elimination can be delayed in older patients, regulatory information advises that dose adjustment may be necessary due to potential for accumulation.

Q: What does the research say about Masti-Clear's effectiveness in children?

Regulatory labeling includes specific dosages and indications for the use of the active ingredient in infants and children for certain severe infections. The fact that official guidance is provided for these populations suggests that effectiveness for the labeled conditions is established.

Q: Is Masti-Clear safe to use for people who have kidney problems?

Use is conditional for people with impaired kidney function. Official warnings note that poor kidney function can cause the drug to accumulate, which increases the potential for serious nervous system effects, known as neurotoxicity. Official guidance recommends close medical monitoring, and a dose adjustment is often necessary under these conditions.

Q: Can Masti-Clear affect liver function?

Official regulatory reports have linked the drug to affecting liver function. Rare adverse reactions such as hepatitis (liver inflammation) and cholestatic jaundice have been reported in the drug's safety profile.

Q: What happens if Masti-Clear is taken for longer than the recommended duration?

Official documents indicate that treatment lasting longer than five days may increase the risk of an overgrowth of non-sensitive organisms, such as fungi or certain resistant bacteria. In cases of extended treatments, medical guidance often includes the need for additional monitoring such as blood tests.

Q: Is Masti-Clear considered a long-term treatment or short-term?

This medicine is typically used for a set, short duration to treat acute infections. However, official documentation notes that a long-term treatment over several weeks may be necessary for specific persistent conditions. The specific duration of use is determined by the condition being treated and is subject to medical oversight.

Q: Does Masti-Clear affect mood or mental clarity?

The medicine's safety profile includes reports of neurotoxicity, which affects the nervous system. Symptoms associated with high concentrations in the body have included changes to mental clarity, such as confusion, severe agitation, or psychosis. This is typically seen in patients with underlying risk factors.

Q: Is Masti-Clear a generic drug or a brand-name drug?

Masti-Clear is a brand name given to the drug by its manufacturer. The active ingredient it contains, Benzylpenicillin (or Penicillin G), is the generic agent.

Q: What ingredients are in Masti-Clear besides the main active component?

Official labeling indicates that the medicine is an injectable suspension. It contains the active component in a salt form along with several inactive ingredients designed to stabilize the drug and form the suspension. These may include buffers, preservatives, and thickening agents like povidone or carboxymethylcellulose sodium.

Q: What happens if a pregnant person accidentally takes Masti-Clear?

Official information states that the drug is generally permitted during pregnancy but advises it should only be used when clearly needed. There is no specific protocol detailed in the regulatory information for an accidental, isolated exposure. Use during pregnancy is subject to medical necessity as outlined in regulatory guidance.

Q: What is the official safety classification of Masti-Clear during pregnancy?

The Australian TGA classification for this drug is Category A, indicating that it has been taken by many pregnant women without evidence of increased harm. The US FDA system is currently transitioning away from categories (like A, B, C) to a detailed risk summary.

Q: What is the half-life of Masti-Clear, and what does that mean?

The term half-life refers to the time it takes for the amount of medicine in the body to be reduced by half. The official labeling for this drug’s injectable suspension describes a slow release from the injection site, which results in much lower but more prolonged concentrations of the drug in the blood over time.

Q: Is it normal to have a slight headache when first starting Masti-Clear?

Headache is listed as an officially documented adverse reaction in some regulatory information. It is sometimes mentioned in association with other more severe systemic symptoms or reactions, such as the Jarisch–Herxheimer reaction or signs of neurotoxicity.

How should Masti-Clear be stored and disposed of?

How to Store and Dispose of Masti-Clear?

The official labeling defines specific storage and handling requirements for Masti-Clear (a Benzylpenicillin suspension) to maintain product integrity and safety.


Required Storage Conditions

Element Regulatory Requirement
Temperature Store in a refrigerator between 2 C and 8 C (36 F and 46 F).
Protection Keep in the original package to protect from light.
Prohibited Do not freeze, as this can compromise the suspension's stability.

Handling and Disposal

The product must be stored out of the sight and reach of children. The container should be kept tightly closed when not in use. After administration, the empty container must be discarded and not reused. Any unused or expired medicine must be disposed of in accordance with local requirements and should not be thrown into household waste or wastewater.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

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