Shotapen

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Shotapen

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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 Shotapen

Quick Facts

Property Description
Active Ingredients Benzylpenicillin and Dihydrostreptomycin
Form Injectable Oily Suspension
Pharmacological Class Antibiotic (Fixed-Dose Combination)
General Purpose Provides broad-spectrum bactericidal action
Origin Semi-synthetic (Derived from natural sources)

What Type of Antimicrobial is Shotapen?

Shotapen is an antimicrobial agent classified as a fixed-dose combination antibiotic developed exclusively for veterinary use, primarily targeting livestock. This product belongs to the broader antibiotic pharmacological class, combining a penicillin-type agent with an aminoglycoside. The medicine is provided as an injectable oily suspension, a specific formulation characteristic that defines its route of delivery (intramuscular) and duration of effect. The active ingredients are semi-synthetic in origin, resulting from the modification of structures derived from natural microbial processes to optimize their therapeutic profiles.

Understanding the Dual Composition: Benzylpenicillin and Dihydrostreptomycin

Shotapen is characterized by the strategic pairing of two distinct active ingredients: Benzylpenicillin (often included as the prolonged-action salt, Procaine Benzylpenicillin) and Dihydrostreptomycin (typically as the sulfate salt). These two components—a beta-Lactam and an Aminoglycoside—are intentionally formulated to be synergistic, enhancing each other’s effects. This combination is recognized for its ability to target a broader scope of both Gram-positive and susceptible Gram-negative organisms. Pairing a beta-lactam, which disrupts the bacterial cell wall, with an aminoglycoside, which inhibits protein synthesis, is a strategy used to expand antimicrobial activity.

General Purpose and Core Function

The primary purpose of Shotapen is to achieve a rapid and efficient bactericidal effect, which actively kills susceptible bacteria that cause infection, such as those involved in respiratory conditions. This germ-killing function is critical for halting the progression of bacterial pathology. The physical form of an oily suspension is central to its general function, as the base is engineered for intramuscular administration to provide a sustained-release action. The sustained-release property helps in maintaining drug concentrations over time, ensuring continuous therapeutic support.

Regulatory References

  1. European Medicines Agency

What side effects are possible with Shotapen?

Possible side effects and safety information

The safety profile of this fixed-dose combination antibiotic is established by official regulatory documentation, classifying possible adverse reactions and defining specific usage restrictions. The documented side effects are categorized by frequency and the organ systems involved.

Adverse Reactions and Frequency

The most serious reaction documented is hypersensitivity (allergic reaction) to the penicillin component, which is classified as rare and may very rarely result in fatal outcomes. Local reactions at the injection site are common, typically presenting as mild and transient.

System-Organ Class Example Effects (If Applicable) Frequency
Immune System Disorders Hypersensitivity, Anaphylaxis Rare to Very Rare
General Disorders Pyrexia (Fever), Listlessness Occasionally
Nervous System Disorders Inco-ordination Occasionally

Safety Considerations in Specific Groups

Official labeling identifies specific populations requiring safety consideration. Young piglets (suckling and fattening) are susceptible to systemic toxic effects which, although often transient, have been reported to be potentially lethal when administered at higher doses. Use of the product is contraindicated in animals with existing liver disease and should be used with caution in cases of defective renal function.

Safety Restrictions and Limitations

Administration is prohibited in certain species, notably rabbits and small rodents. Furthermore, the combination is generally not recommended for simultaneous use with other antibiotics known to possess oto- or nephrotoxic effects to avoid compounded risks. These classifications strictly reflect the official safety profile as communicated by governmental regulatory authorities.

Overdose and Emergency Response

Overdose and when to seek help

Shotapen contains Procaine Penicillin G and Dihydrostreptomycin. The official overdose profile is based on the known toxicities of these components. This information describes the documented risks of excessive exposure and the required emergency actions, as specified in regulatory documents.

Documented Overdose Manifestations

System Affected Manifestations
Central Nervous System (CNS) Neuromuscular hyperirritability, seizures, confusion, agitation, and hallucinations (associated with high procaine levels).
Systemic/Allergic Severe, occasionally fatal hypersensitivity (anaphylactic) reactions.

Required Emergency Actions

In the event of an overdose or a severe reaction, the drug should be discontinued immediately.

When to Seek Immediate Medical Help: Immediate emergency treatment is mandated for signs of a serious anaphylactic reaction, such as difficulty breathing, swelling of the face or throat, or circulatory collapse. Emergency treatment requires the administration of Epinephrine, oxygen, and airway management.

Supportive Management: There is no specific pharmacological antidote listed in official documents. Treatment for overdose is symptomatic and supportive, focusing on stabilizing the patient and managing specific symptoms like CNS hyperactivity or electrolyte imbalance. Patients with pre-existing conditions, particularly renal impairment, may be at higher risk for complications following overdose.

Therapeutic Uses of Shotapen

Quick Facts

  • Targeted Conditions: Respiratory infections, metritis, erysipelas, leptospirosis, and urinary tract infections.
  • Broad-Spectrum Efficacy: Used for infections caused by both Gram-positive and Gram-negative bacteria.
  • Extended-Release: Provides sustained therapeutic levels of the antibiotics in the body.

What Shotapen Treats: Main Uses and Benefits

Shotapen is a veterinary medicinal product designated for the treatment of bacterial infections in susceptible livestock, including cattle, pigs, and horses, and companion animals such as dogs and cats. The product is an injectable suspension used to address a broad range of bacterial microorganisms that can cause disease.

Its main uses include the management of conditions such as respiratory infections (like pneumonia), postpartum infections (such as metritis), leptospirosis, and swine erysipelas. It is also indicated for the treatment of urinary tract infections and infected wounds.

A significant benefit of this formulation is its extended-release properties. The combination of active compounds provides a sustained therapeutic level of the antibiotic agents within the animal's system, reducing the frequency of administration needed for effective treatment. This formulation is designed for long-acting antimicrobial management in veterinary medicine.

Eligibility and Restrictions for Use

The eligibility for using Shotapen (Benzylpenicillin/Dihydrostreptomycin) is strictly defined by regulatory authorities based on the animal's species and pre-existing health status. It is a veterinary product approved for target species including cattle, pigs, horses, dogs, and cats. Use is also permitted in young animals, such as calves and piglets.


Populations for whom use is contraindicated

Official labeling mandates that Shotapen must not be used in the following groups:

  • Hypersensitivity: Animals with a known allergy to penicillins, procaine, and/or dihydrostreptomycin.
  • Small Herbivores: Prohibited for rabbits, guinea pigs, hamsters, and other small rodents.
  • Organ Impairment: Animals with seriously impaired renal function (kidney disease) or liver disease.

Eligibility-Related Restrictions

  • Lactation/Food Safety: Milk from dairy animals under treatment must not be used for human consumption during treatment and for a mandatory withdrawal period afterwards.
  • Pregnancy: Use in pregnant animals requires caution, at the discretion of the prescriber.

What should I know about interactions with other medicines?

Shotapen Interactions with other medicines and products

Official regulatory information identifies specific drug classes and agents that are restricted or prohibited for co-administration with Shotapen (Benzylpenicillin/Dihydrostreptomycin) due to documented interaction risks.


Contraindicated Combinations and Prohibitions

Classification Interacting Substances/Classes Interaction Basis in Regulatory Documents
Contraindicated Other Aminoglycosides (e.g., Gentamicin) Risk of additive toxicity, specifically increased oto- and nephrotoxicity from the dihydrostreptomycin component.
Prohibited Co-Use Loop Diuretics (e.g., Furosemide) Increased risk of ototoxicity (ear damage) when combined with the dihydrostreptomycin component.
Antagonism Risk Principally Bacteriostatic Antibiotics (e.g., Tetracyclines, Macrolides, Amphenicols) Potential for pharmacodynamic antagonism that may interfere with the bactericidal action of penicillin.
Potentiation Risk General Anesthetics, Muscle Relaxants Risk of potentiation of neuromuscular blocking effects associated with the dihydrostreptomycin component.

Other Documented Constraints

  • Physical and Chemical Incompatibility: The regulatory label notes that the suspension is incompatible with certain injectable agents, such as Heparin, Calcium Gluconate, and Riboflavin, which should not be mixed in the same syringe for administration.
  • Population-Specific Note: Although not a drug-drug interaction, the product label notes that the risk of dihydrostreptomycin toxicity is heightened in animals with renal dysfunction due to reduced drug clearance, serving as an important condition-specific restriction.

Mechanism of Action

How Shotapen Works

Shotapen exerts its action through two distinct and complementary molecular mechanisms targeting the fundamental structures and functions of susceptible bacteria, ensuring a robust germ-killing effect.


Dual-Target Bactericidal Action at the Molecular Level

The beta-lactam component, Benzylpenicillin, acts as an irreversible inhibitor of Penicillin-Binding Proteins (PBPs)—enzymes critical for building the rigid peptidoglycan layer. This arrests the cross-linking required for structural integrity, leading to cell wall failure. Concurrently, Dihydrostreptomycin binds to the 30S ribosomal subunit, disrupting protein synthesis and causing the production of faulty, non-functional bacterial proteins. This combined molecular failure results in microbial elimination through a bactericidal mechanism .


Mechanistic Synergy and Sustained Target Saturation

The structural damage inflicted by Benzylpenicillin facilitates the uptake of Dihydrostreptomycin into the microbial cell, creating a highly effective synergistic mechanism. This coordinated action leads to a widened range of microbial susceptibility to the combined action. Furthermore, the oily formulation and the Procaine component create a depot effect, enabling the slow, continuous release of both antibiotics. This process ensures sustained target saturation, which maintains the concentration required for continuous microbial inhibition, allowing the mechanism to achieve a continuous bactericidal effect over time.

Dosage and Administration Information

The administration of Shotapen (Procaine Benzylpenicillin and Dihydrostreptomycin Sulphate Suspension for Injection) involves protocols for the application of this combination antibiotic. The parameters for usage include the route, frequency, and duration intended to maintain therapeutic standards.


Administration Route and Preparation

Shotapen is administered via Deep Intramuscular Injection. Because the formulation is an oily suspension, a specific preparation step is involved: the vial is shaken well immediately prior to drawing the dose. This action supports the uniform distribution of both active ingredients within the suspension.


Dosing Schedule and Treatment Duration

The medication is delivered once daily (QD). The standard regimen involves a volume of 1 ml per 25 kg bodyweight. This ratio corresponds to a fixed-dose delivery of 8 mg/kg of Procaine Penicillin and 10 mg/kg of Dihydrostreptomycin Sulphate. The defined treatment course is a fixed, short-term duration, limited to up to three consecutive days.


Procedural Constraints

A procedural constraint involves adhering to maximum volume limits per injection site, which vary by species. For example, the maximum volume per site is 15 ml for horses and 6 ml for cattle. This determines how the total calculated dose is divided and administered to multiple sites if the total volume exceeds the limit.

Recent Clinical Evidence

Research Evidence / Overview of Studies for Shotapen


Evidence for Use in Respiratory and Systemic Infections

The research base for the combination of Benzylpenicillin and Dihydrostreptomycin includes Target Animal Effectiveness Studies (TAES), which are primarily comparative field trials, as well as official regulatory data. This evidence was studied for conditions like bacterial respiratory infections and systemic diseases like Swine Erysipelas. In these studies, researchers examined outcomes such as changes in acute symptoms, the disappearance of the target bacteria (bacteriological clearance), and survival rates in the observed animal groups, which included cattle, pigs, horses, and sheep/goats.

The evidence foundation relies on regulatory reviews and field data that tracked outcomes for these specific bacterial targets. For Swine Erysipelas, the regulatory data show patterns related to the status of acute clinical signs, such as fever and skin lesions, during the short-term period. Research indicates that the impact of antimicrobial resistance patterns on the medicine's studied outcomes is constantly changing.

Evidence for Use in Reproductive and Zoonotic Conditions

Research was studied for post-partum infections, such as metritis, and for the zoonotic disease Leptospirosis. For postpartum conditions, the evidence often consists of field trials and observational data. Researchers monitored the time-course of clinical signs—such as uterine discharge—and also tracked longer-term outcomes related to reproductive function.

For Leptospirosis, the research explored the potential for the aminoglycoside component to achieve bacteriological clearance. This area of study relies heavily on pharmacological studies (PK/PD) that estimate drug concentrations, supported by studies on the action of the aminoglycoside component against this pathogen. The reliance on pharmacological surrogates means that clinical trial data specifically validating outcomes for the fixed combination for this indication remains limited.

What is Still Uncertain about the Research Foundation

One key limitation is the variability across studies regarding the specific chemical structure of the penicillin component (e.g., Procaine vs. Procaine/Benzathine). This variability contributes to the difficulty of drawing consistent conclusions across the entire body of research. Furthermore, some scientific literature highlights questions regarding the pharmacological support for the two-drug combination compared to using a single penicillin agent. Ultimately, the evidence base helps contextualize what has been observed so far but does not provide guarantees.

Frequently Asked Questions (FAQ)

Common questions about Shotapen (FAQ)

Q: Can Shotapen cause stomach upset, like diarrhea or nausea?

A: Official regulatory reporting systems actively monitor for potential adverse events in animals, including gastrointestinal effects such as vomiting and diarrhea. If signs of stomach upset are observed, it is standard practice to report these effects to the administering veterinarian or the drug manufacturer for monitoring.

Q: Is Shotapen appropriate for pregnant or nursing animals?

A: According to the official product information, Shotapen requires caution when used in pregnant animals and requires evaluation by the attending veterinarian. Additionally, the milk from treated dairy animals must not be used for human consumption during the treatment period and for a specified time afterward, known as the withdrawal period.

Q: How long is the withdrawal period for meat and milk after using Shotapen in cattle?

A: Official regulatory documents define specific withdrawal periods, which can vary based on the product formulation and local regulations. For example, the required waiting period for milk consumption may be around five days after the final dose, and the withdrawal period for meat might be approximately 49 days in cattle.

Q: What is the difference between the Procaine Benzylpenicillin and the Benzathine Benzylpenicillin forms?

A: Procaine and Benzathine refer to different salts of the penicillin component, and both are designed to slow down the release of the drug. Procaine Benzylpenicillin provides a sustained-release effect over a shorter duration, such as 24 hours. Benzathine Benzylpenicillin is a less soluble salt, which means it absorbs more slowly and delivers a longer-lasting effect, often over several days.

Q: Can Shotapen be used to prevent certain bacterial infections?

A: Official product information primarily indicates Shotapen for the treatment of established acute and chronic bacterial diseases in target species. Any prophylactic (preventative) use should be consistent with the specific indications approved on the product label and is determined by a veterinarian.

Q: Are there any reported cases of antibiotic resistance developing to the components in Shotapen?

A: Regulatory agencies emphasize the importance of using antibiotics responsibly to reduce the threat of resistance. The product information acknowledges that antimicrobial resistance patterns are always changing, which is why official bodies place antibiotics like Shotapen under strict veterinary oversight to preserve their effectiveness.

Q: Is Shotapen an older or newer generation of antibiotic?

A: The active ingredients in Shotapen, Penicillin G and Dihydrostreptomycin, are well-established, traditional antibiotics that have been in use for many decades. They are classified as medically important antimicrobials but are not considered newer-generation antibiotics.

Q: Why is renal function a consideration when administering Shotapen?

A: Renal (kidney) function is important because the dihydrostreptomycin component is primarily removed from the body by the kidneys. If an animal has impaired kidney function, the drug may not be cleared properly, leading to accumulation in the body and a heightened risk of toxicity.

Q: Does the color or appearance of the suspension indicate anything about its quality?

A: The official label specifies the expected appearance of the suspension, which is often described as white. Any significant change in the color, consistency, or clarity of the product before use could signal a quality issue; such changes are typically brought to the attention of the veterinarian or the product supplier.

Q: Is Shotapen effective against infections caused by Staphylococcus or Streptococcus species?

A: Yes, official pharmacological information states that the penicillin component in Shotapen is highly active against many Gram-positive bacteria. These include common types of infectious bacteria such as Staphylococcus species and Streptococcus species.

Q: What steps should be taken if an injection site reaction occurs?

A: Injection site reactions are common and often mild with this type of suspension. The regulatory guidance is to monitor the animal and report any adverse events, including any significant or concerning reaction at the injection site, to the drug manufacturer or the relevant veterinary authority for assessment.

Q: How does the Procaine element contribute to the immediate effect versus the long-acting effect?

A: The Procaine component is chemically bound to the penicillin to create a 'depot effect' in the muscle, which is the mechanism for the drug's slow, continuous release and long-acting effect. Separately, the Procaine itself also functions as a local anesthetic, which is intended to reduce any discomfort from the injection.

How should Shotapen be stored and disposed of?

How to Store and Dispose of Shotapen

The storage of Shotapen, an injectable veterinary antibiotic suspension, must strictly follow regulatory labeling to ensure stability and efficacy.

Storage Conditions

Official documents require the product to be stored under controlled conditions, often within the range of 2 C to 25 C, and explicitly state to do not freeze.

The container must be kept in a dry, dark place to protect the contents from light and moisture degradation. A critical stability constraint is that the shelf life after the container is first opened is limited to 28 days.

Handling and Disposal

For safety, the medicine must be stored in a location inaccessible for children. Disposal of unused or expired product must be managed in accordance with local requirements, with necessary precautions taken to prevent the veterinary antibiotic from entering the environment.

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

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