Carena

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Medically reviewed

Marina Burgos

Last updated on 10/01/2026

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 Carena

Quick Facts

Property Description
Active ingredient Aminophylline (Theophylline ethylenediamine salt)
Form Tablet, Solution, Suppository, Injection
Pharmacological class Bronchodilator, Methylxanthine Derivative
General Purpose Relieving restricted airflow and easing breathing
Origin Synthetic, Chemically Derived Salt

What Type of Medicine is Carena?

Carena is a pharmaceutical preparation containing the active substance Aminophylline, which is structurally classified as a methylxanthine derivative and belongs to the primary therapeutic class of bronchodilators. The general purpose of this medicine is to promote smooth muscle relaxation within the respiratory tract, thereby mitigating airway obstruction and easing breathing.

Aminophylline is recognized as a systemic bronchodilator. The medicine is designed to dilate the bronchi and bronchioles, thereby decreasing resistance in the respiratory airway. This synthetic substance functions as an agent for managing issues related to reversible airflow resistance in various respiratory conditions.

Composition and Pharmaceutical Formulations

The active ingredient, Aminophylline, is chemically defined as a synthetic ethylenediamine salt of theophylline, making it a combination product in its formulation. This compound consists of theophylline and ethylenediamine typically in a two-to-one ratio. The strategic incorporation of ethylenediamine is crucial because it enhances the water solubility of the active component, Theophylline, which is otherwise poorly soluble.

This characteristic solubility feature enables the preparation to be offered in diverse systemic dosage forms including Tablet and oral Solution, as well as specialized sterile Injection for parenteral administration. This formulation ensures stable delivery and suitability across various clinical environments.

Core Function: How Carena Eases Breathing

The core function of Carena is to achieve bronchodilation, which is the process of widening the breathing passages in the lungs. This physiological effect translates to the benefit of facilitating respiration by relieving the sensation of restricted airflow. The active ingredient, Theophylline, works by influencing cellular pathways to relax the tension in the smooth muscles surrounding the bronchi, and it contributes to increased diaphragmatic contractility. These combined actions address the mechanical restriction in the airways, serving the drug's fundamental purpose of improving the capacity for more comfortable breathing.

Regulatory References

  1. StatPearls (NIH) on Aminophylline
  2. MedlinePlus (NIH) Drug Information for Aminophylline
  3. DrugBank Online Aminophylline Entry

What side effects are possible with Carena?

Adverse Reaction Scope

Adverse reactions associated with Carena are documented by regulatory authorities and are generally classified by the system or organ they affect, including Nervous System, Gastrointestinal, and Cardiac disorders. These reactions often reflect the stimulant properties of the active ingredient, Aminophylline.

Classification Examples of Officially Listed Reactions
Common Effects Nausea, vomiting, headache, insomnia, fine skeletal muscle tremors, and restlessness [NIH MedlinePlus].
System-Organ Classes Cardiac disorders (e.g., tachycardia, palpitations, irregular heartbeat) and Nervous system disorders (e.g., seizures, confusion, irritability) [FDA Label].
Serious Reactions Officially documented serious adverse reactions include potentially lethal intractable seizures, severe ventricular arrhythmias, and cardiac arrest, often occurring without prior clinical warning at toxic concentrations [FDA-Philippine].

Safety Classifications and Risk Patterns

Carena is documented by regulatory bodies as having a narrow therapeutic index, meaning the window between effective serum concentration and concentrations associated with toxicity is small [RWANDA FDA SmPC].

  • Concentration-Dependent Risk: The frequency and severity of adverse reactions are explicitly linked to the amount of the drug in the bloodstream. Adverse effects increase significantly when the serum concentration of theophylline (the active component) exceeds 20 mcg/mL [FDA Label].
  • Special Population Notes: Official labeling advises caution and careful monitoring for certain patient groups. Older adults and patients with hepatic (liver) impairment require particular attention due to a reduced capacity to clear the medicine, which increases the risk of toxicity [RWANDA FDA SmPC]. Infants and children under one year of age are also noted for having a higher risk of serious side effects [Mayo Clinic].
  • Administration Safety: Rapid intravenous injection of the solution is explicitly documented as a safety concern that may lead to severe hypotension and sudden death [FDA-Philippine].

Resulting Safety Structure

The official safety profile of Carena is governed by its narrow therapeutic index, formally linking the risk of adverse effects to the level of drug exposure. This regulatory framework emphasizes that the potential for serious cardiac and neurological events is a primary feature of the safety profile, necessitating careful monitoring, particularly in vulnerable populations and when serum levels approach the toxic threshold.

Overdose and Emergency Response

Carena overdose is a condition classified by regulatory authorities as potentially leading to severe and life-threatening toxicity, often associated with serum concentrations exceeding 20 mu g/mL. Manifestations commonly documented in official labeling include gastrointestinal effects like severe nausea, vomiting, and abdominal pain, along with CNS effects such as persistent headache, tremors, restlessness, and confusion. Cardiac symptoms such as sinus tachycardia (rapid heart rate) and palpitations are also frequently noted.

The most serious outcomes described in regulatory documents are seizures and life-threatening ventricular arrhythmias (irregular heart rhythms), which carry a documented risk of permanent brain damage or death. The risk of severe complications is also markedly higher in specific populations, including the elderly and patients with pre-existing hepatic impairment due to reduced drug clearance.

The official regulatory response mandates seeking immediate medical attention and calling emergency services or the Poison Help Line immediately upon suspected overdose or the onset of severe symptoms like convulsions or persistent vomiting. Management focuses on intensive supportive care, including continuous vital signs monitoring and the measurement of serum theophylline concentrations. Procedures such as multiple-dose activated charcoal and hemodialysis may be required for critical toxicity, as no specific antidote is known.

Therapeutic Uses of Carena

What Carena Treats: Main Uses and Benefits

The primary therapeutic use of Carena is aligned with treating conditions that cause noticeable constriction of the air passages. The drug is used for relieving symptoms related to conditions like asthma, chronic bronchitis, and emphysema, which may assist with making it easier to breathe.

Carena is generally used to provide supportive relief during acute exacerbations of chronic obstructive lung diseases, especially when symptoms become more disruptive during flare-ups. It is relevant for easing the symptoms related to heightened physiological activity, such as severe wheezing and intense shortness of breath. It is commonly used to help manage symptoms associated with acute or episodic changes in adults, adolescents, and children.

In specialized medical contexts, Carena may assist with addressing symptoms associated with acute changes in highly vulnerable populations, such as premature infants. This application is commonly used to help with specific breathing difficulties, and may assist with functional stability in conditions where functional stability becomes affected.


Quick Fact: Relief for Restricted Airflow

Symptom Domain Clinical Context Patient Benefit
Severe Wheezing Acute Exacerbations Contributes to easing the overall symptom load
Shortness of Breath Adjunct Therapy Supports day-to-day comfort and functional stability
Airway Constriction Specialized Neonatal Care Helps support basic respiratory function

Regulatory References

  1. NIH MedlinePlus overview

Eligibility and Restrictions for Use

The eligibility for Carena is determined by regulatory agencies based on established contraindications and physiological factors that affect drug clearance. Carena is intended for use in adults, adolescents, and children.


Contraindications

Carena must not be used by patients who have a known hypersensitivity or allergy to xanthine derivatives (like theophylline) or to the ethylenediamine component of Carena. It is also prohibited for patients who are already receiving other xanthine medicines concurrently. Specific regulatory labels also contraindicate use in patients with acute porphyria or coronary artery disease where cardiac stimulation may be harmful.

Restricted or Conditional Use

Use requires caution and monitoring in several populations due to reduced clearance, which increases the risk of toxicity:

  • Extremes of Age: The elderly (over 60) and children under one year (especially neonates) must be monitored closely.
  • Comorbidities: Patients with congestive heart failure, liver disease, acute fever, or sepsis require caution.

Pregnancy and Lactation

  • Pregnancy: Use is restricted and permitted only when considered essential by a physician.
  • Lactation: The active substance passes into breast milk and may cause irritability in infants; use is conditional and generally not recommended.

What should I know about interactions with other medicines?

Official Interaction Restrictions

Interactions involving Carena are formally documented by regulatory authorities, focusing on changes to the active component, Theophylline, or additive pharmacological effects. Co-administration with other xanthine derivatives (e.g., Theophylline) is formally contraindicated due to the officially documented risk of severe, additive toxicity. The substance Riociguat is also generally listed as not recommended for co-use.

Pharmacokinetic Interactions (Altered Clearance)

Many interactions result from substances that alter Theophylline's clearance, which modifies systemic exposure.

  • Decreased Clearance (Increased Exposure): Substances that reduce clearance, leading to a potential for increased plasma concentrations, include the antibiotics Ciprofloxacin and Erythromycin, as well as Cimetidine and Fluvoxamine.
  • Increased Clearance (Decreased Exposure): Medicines documented to increase clearance include the antiepileptics Phenytoin and Carbamazepine, and the anti-tuberculosis medicine Rifampicin.

Pharmacodynamic and Lifestyle Factors

Other documented interactions relate to additive physiological effects or lifestyle factors affecting clearance:

  • Additive Effects: Co-administration with Beta-2-adrenergic agonists or certain Diuretics carries an officially documented increased risk of hypokalaemia. The CNS stimulant effects may be intensified by Sympathomimetics and caffeine-containing foods and beverages.
  • Environmental Factors: Cigarette smoking is documented to increase Theophylline clearance. Furthermore, conditions such as acute fever (high temperature) and hepatic impairment (e.g., cirrhosis) are officially noted to reduce clearance, raising the inherent risk of concentration-dependent effects.

Mechanism of Action

The physiological effects of Carena are derived from the multifactorial actions of its active moiety, Theophylline, primarily through three distinct mechanistic domains. The drug's mechanism is determined by the combined, simultaneous modulation of key enzymes and receptors, rather than a single target.

Enzymatic Smooth Muscle Relaxation

This domain involves the nonselective inhibition of Phosphodiesterase (PDE) enzymes within the airways. By blocking this enzyme, the drug prevents the breakdown of the cellular messenger cAMP, leading to increased cAMP levels and a direct relaxation of the bronchial smooth muscle.

Receptor Modulation and Muscle Function

Theophylline acts as a nonselective antagonist at Adenosine Receptors across multiple tissues. Blocking these receptors prevents adenosine-mediated signals that mediate smooth muscle contraction, while simultaneously altering calcium handling in the diaphragm. This receptor modulation increases the force and sustains the contractility of the primary breathing muscle.

Anti-Inflammatory Pathway Regulation

This secondary, dose-dependent mechanism involves the restoration of Histone Deacetylase 2 (HDAC2) function, often impaired by oxidative stress, achieved in part through the inhibition of PI3K-delta. This modulatory action suppresses the transcription of specific pro-inflammatory genes, which influences the activity level within the targeted pathways.

Dosage and Administration Information

Carena administration is defined by its purpose, distinguishing between the Intravenous (IV) Infusion for rapid, acute intervention and Oral dosage forms for chronic, long-term maintenance therapy.

Dosing is highly procedural and relies on patient-specific factors. For acute use, the IV loading dose is calculated at approximately 5 to 6 milligrams per kilogram (mg/kg), based on the patient's ideal body weight. This IV dose must be administered slowly, typically over 20 to 30 minutes, and is required to be diluted in a standard infusion solution prior to use. Maintenance therapy continues either via a continuous intravenous infusion or through oral forms, which are often taken in divided doses or as a once- or twice-daily extended-release regimen. Oral administration should be consistent relative to meals to promote stable blood levels.

Crucially, dosage must be controlled using Therapeutic Drug Monitoring (TDM) to measure and adjust the serum drug concentration. Standard clinical practice involves population-specific adjustments; older adults, as well as patients with hepatic impairment, typically require a significantly lower maintenance rate compared to younger adults due to reduced drug clearance. Extended-release tablets must be swallowed whole and not crushed.

Recent Clinical Evidence

Research Evidence / Overview of Studies for Carena (Aminophylline)

This section summarizes the official clinical research and scientific reviews that examine the use of Carena. It outlines the specific study designs, the outcomes that researchers monitored, and areas where the evidence remains limited or inconsistent.


Evidence for Acute Exacerbations of Asthma

The use of Carena was studied for patients experiencing acute, episodic changes associated with asthma flare-ups. Research exploring these short-term symptom changes primarily relies on Randomized Controlled Trials (RCTs) and comprehensive Systematic Reviews. The studies monitored functional pulmonary measures and healthcare utilization parameters (such as hospital stay duration). Findings describe patterns with some trials reporting measured changes in lung function parameters; however, for major clinical endpoints like hospital admission rates, findings were mixed, and data do not describe consistent patterns. Most studies examined Carena as an addition to standard therapy, but the resulting evidence is limited regarding the consistent impact on major outcomes, and certainty remains low in drawing broad conclusions.

Evidence for Acute Exacerbations of Chronic Obstructive Pulmonary Disease (COPD)

Carena was evaluated in research contexts involving fluctuating or unstable symptoms in patients with acute exacerbations of COPD, primarily adults. Researchers monitored physiological strain or stress, including arterial blood gas (ABG) measurements, functional lung measures, and patient-reported outcomes describing perceived discomfort. Some trials described a pattern of temporary change in physiological markers, but when examining clinical outcomes like length of hospital stay, findings were mixed, indicating no consistent difference compared to control groups or placebo. Data for certain groups remain insufficient, especially for long-term outcomes following the acute event.

Evidence for Apnea of Prematurity (AOP)

Carena was studied for its role in conditions characterized by functional limitations in premature infants. Studies examined the frequency of breathing cessation episodes and the duration of respiratory support. Trials reported how symptoms evolved, with findings describing a pattern of fewer breathing cessation episodes and sometimes a shorter duration of required ventilator support. However, comparative evidence indicates that measured effects on primary outcomes appear to be similar to those of alternative standard treatments, though specific non-respiratory findings were observed more frequently. Long-term effects are not fully established.

Key Studies & References

  1. National Institute for Health and Care Excellence (NICE) Guidelines - Asthma: diagnosis, monitoring and chronic management

Frequently Asked Questions (FAQ)

Common questions about Carena (FAQ)

Q: How quickly does Carena typically start working?

A: Official information indicates that the intravenous (IV) form of Carena is designed for rapid, acute intervention. The effect of widening the breathing passages is generally linked to the active component achieving its optimal concentration range in the bloodstream, as defined in official documents.

Q: What is the difference between Carena and a supplement?

A: Carena is defined by regulatory bodies as a pharmaceutical preparation and a prescription-only drug in the methylxanthine derivative class. This classification means it is officially authorized and regulated by government health agencies for the medical treatment of specific conditions, which differs from the regulatory classification of a dietary supplement.

Q: Can older adults generally use Carena?

A: Use in older adults (typically defined as over 60) is addressed in official documents, but regulatory information emphasizes the need for caution and close monitoring. This is due to a reduced capacity in this population to clear the medicine from the body, which increases the risk of concentration-dependent adverse effects.

Q: Is there any research on long-term use of Carena?

A: Official research summaries available in regulatory documentation tend to focus on its use for acute exacerbations of respiratory conditions and specific conditions in premature infants. Regulatory summaries note that evidence regarding long-term effects is not fully established and state that the certainty for drawing broad conclusions about major long-term clinical outcomes remains low.

Q: Does Carena interact with common pain relievers?

A: Official drug interaction lists identify substances that may reduce the body's clearance of Carena. While specific common over-the-counter pain relievers (such as acetaminophen or NSAIDs) are not listed as primary interactors that alter clearance, the official product information should be consulted for comprehensive interaction details.

Q: Does Carena interact with birth control pills?

A: Official interaction data indicates that co-use with hormonal contraceptives (birth control pills) may increase the plasma concentrations of Carena's active component. This change happens because hormonal contraceptives can affect the medicine's metabolism, and the regulation of drug levels is documented as an important factor when starting or stopping hormonal contraceptives.

Q: Does Carena impact weight?

A: Weight changes (gain or loss) are not consistently documented among the common or serious adverse reactions listed in official regulatory tables for Carena. Official dosing guidelines do note the importance of considering a patient's ideal body weight for calculation purposes.

Q: Is Carena the same kind of drug as [Similar Drug Name]?

A: Carena is a member of the methylxanthine derivative class. Other medicines that are classified in the same pharmacological class share a similar fundamental mechanism of action, but they differ in their specific chemical composition and authorized uses.

Q: Can Carena be used for conditions other than the primary ones listed?

A: Regulatory bodies have granted formal approval and authorization for Carena only for the specific conditions listed in the official product information, such as managing symptoms of reversible airflow obstruction and apnea of prematurity.

Q: Is it common to feel nothing when first taking Carena?

A: Official documents focus on therapeutic and adverse effects rather than a patient's general sensation. The expected clinical effect of muscle relaxation and easier airflow is typically associated with the medicine's concentration reaching therapeutic levels, though the physical sensation of this effect may vary among individuals.

Q: Why do official documents emphasize a certain safety warning for Carena?

A: Official warnings are highlighted because Carena is documented as having a narrow therapeutic index. This means the drug level required to achieve a therapeutic effect is close to the level at which severe adverse reactions, such as seizures and cardiac issues, may occur.

Q: What is the purpose of the different strengths of Carena?

A: The multiple strengths and authorized forms of Carena (such as IV infusion and oral tablets) support different therapeutic strategies. The IV form is authorized for rapid, acute intervention, while oral dosage forms are intended to support chronic, long-term maintenance therapy requiring stable blood levels.

Q: How is Carena's use different in children compared to adults?

A: The use of Carena differs across age groups, especially regarding safety and monitoring. Regulatory guidance notes that children under one year (neonates) have a unique risk profile and often require close supervision. Dosing is often weight-based for children, and the intravenous administration is a careful, procedural calculation.

Q: If I miss a dose of Carena, what does the official guidance say?

A: General regulatory guidance on missed doses often advises against taking a double dose to compensate for the missed one. Due to the importance of maintaining stable blood levels and the narrow therapeutic window, patients should always refer to their specific prescribed instructions for managing a missed dose.

Q: Do you have to take Carena at the exact same time every day?

A: Regulatory guidance emphasizes the importance of consistent administration. Taking the medicine at a consistent time, including relative to meals, is noted as important to promote stable blood levels. Maintaining stable levels is crucial because official protocols often require Therapeutic Drug Monitoring (TDM) to control the serum drug concentration.

Q: Does Carena affect driving or operating machinery?

A: Official warnings exist advising caution with activities like driving or operating machinery. The medicine may cause central nervous system effects such as dizziness, light-headedness, or fits (convulsions), and official product information should be consulted to understand potential reactions.

Q: Are there different types of interactions listed for Carena?

A: Yes, official documents categorize interactions into different types. These include Pharmacokinetic interactions, which affect how the body clears the drug (e.g., certain antibiotics), and Pharmacodynamic interactions, which cause additive physiological effects (e.g., caffeine or certain cardiac medicines).

Q: Does Carena have any known interactions with herbal products?

A: Official drug interaction databases specifically note that certain herbal products, such as St. John’s Wort, may interact with Carena. This interaction can increase the rate at which the body clears the drug, potentially leading to lower serum concentrations and reduced therapeutic effect.

Q: Why is eligibility for Carena sometimes described as complex?

A: Eligibility is considered complex because it is determined by multiple official factors. These include definitive contraindications (conditions where the drug must not be used) and several conditional use factors related to reduced drug clearance, such as extremes of age, congestive heart failure, and liver disease.

Q: Is Carena available over the counter?

A: No. The active component of Carena is consistently classified by major regulatory agencies as a prescription-only medicine in major jurisdictions, meaning it is not legally available without a valid prescription from a licensed healthcare provider.

Q: Does Carena cause fatigue or tiredness?

A: Fatigue or tiredness are not consistently listed among the most common adverse reactions in official regulatory documents. The commonly documented effects often reflect the stimulant properties of the active ingredient, such as restlessness and insomnia.

Q: Is it possible for Carena's effect to wear off over time?

A: Clinical literature and some regulatory discussions acknowledge that the body may adapt to the effects of the active component over a period of time. The ongoing requirement for Therapeutic Drug Monitoring (TDM) is an established protocol to help manage potential changes in drug levels and effectiveness.

Q: What should I do if a side effect of Carena feels unusual?

A: Official guidance requires that patients experiencing signs or symptoms consistent with toxicity, such as persistent vomiting, cardiac arrhythmias, or seizures, should immediately notify a healthcare professional. Other unusual side effects should also be reported to a prescriber.

Q: What kind of studies support the use of Carena?

A: The use of Carena is supported by various study designs, primarily Randomized Controlled Trials (RCTs) and Systematic Reviews. These official studies have monitored parameters such as functional pulmonary measures, breathing cessation episodes in premature infants, and measures of healthcare utilization.

Q: Is it true that Carena can sometimes affect blood test results?

A: The active component of Carena is frequently measured in the blood as part of Therapeutic Drug Monitoring (TDM) to ensure stable and safe levels. Furthermore, regulatory guidelines on its use in respiratory conditions refer to monitoring physiological markers like arterial blood gas (ABG) measurements during acute events, which Carena’s administration may influence.

Q: Why is the full list of ingredients important for Carena?

A: The full list of ingredients is important because Carena is a combination product containing theophylline and ethylenediamine. Regulatory documents explicitly list a known hypersensitivity or allergy to the ethylenediamine component as a definitive contraindication.

Q: If I stop taking Carena suddenly, are there any general expectations?

A: Official discontinuation advice often stresses that stopping long-term maintenance therapy suddenly may lead to a worsening or recurrence of the underlying respiratory symptoms. Patients should seek the guidance of a healthcare professional when considering changes to the administration of any prescribed therapy.

Q: Is Carena used worldwide, or only in certain countries?

A: The active component of Carena is authorized and used globally. Its use, safety profile, and official documentation are maintained by major regulatory agencies across the world, including the FDA (USA), EMA (Europe), Health Canada, and the TGA (Australia).

Q: What is the general duration that Carena is typically prescribed for?

A: Carena is authorized for varying durations depending on the medical need. Official information describes it being administered as an IV infusion for rapid, acute intervention (short-term use) or via oral dosage forms for chronic, long-term maintenance therapy of respiratory conditions.

Q: Why is it important to share my full medical history before starting Carena?

A: Sharing a full history is essential because Carena has numerous official conditional use factors and contraindications documented by regulatory bodies. These include past or current medical conditions such as congestive heart failure, liver disease, acute fever, and coronary artery disease, which directly affect the safety of the medicine.

Q: How is the safety of Carena monitored after it is approved?

A: Safety is officially monitored through a system called pharmacovigilance, also known as post-marketing surveillance. This is the official process mandated by regulatory bodies to continuously collect, assess, and monitor reported adverse effects once the medicine is in general use.

Q: Why might a patient need to switch from one drug to Carena?

A: The decision to switch is a clinical judgment, but official documents describe Carena as functioning through unique pathways, including Phosphodiesterase inhibition and Adenosine Receptor antagonism. These dual mechanisms may offer an alternative therapeutic approach when other medicines are not providing the expected effects.

Q: Are there specific instructions for what to do before a surgery while taking Carena?

A: Official guidance often advises informing the surgical team that Carena is being taken. Regulatory documents specifically note concerns regarding potential drug interactions with certain anesthetic agents and changes in the body's clearance rate of the medicine due to factors like smoking cessation during the perioperative period.

How should Carena be stored and disposed of?

Official Storage and Disposal Requirements

Official regulatory documents define strict conditions for storing and disposing of Carena to ensure its stability and safety.

Storage and Handling Rule Requirement Summary
Temperature and Environment The medicine must be stored at a temperature not exceeding X, C (e.g., 25, C or 30, C). It must not be frozen or exposed to excessive heat.
Protection and Packaging Keep Carena in its original container, which is often required to be tightly closed and protected from light and moisture. The label specifies the official shelf-life or any use-by period after opening.
Child Safety Regulatory guidelines universally require that all medicine, including Carena, must be kept out of the sight and reach of children at all times.
Disposal Unused or expired Carena must be disposed of through authorized collection sites, such as drug take-back programs at pharmacies or law enforcement agencies. Unless the medicine is on a specific national flush-list, it must not be poured down a sink or toilet or thrown into household trash due to environmental concerns.

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

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