Orfenal

Orphenadrine

Method of action: Miorelaxant

Treatment option:

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 Orfenal

Property	Description
Active Ingredient	Orphenadrine (citrate or hydrochloride)
Form	Oral tablet, Extended-release tablet, Injectable solution
Pharmacological Class	Centrally acting skeletal muscle relaxant, Anticholinergic agent
Common Use	Symptomatic relief of acute muscle spasms and stiffness
Origin	Synthetic tertiary amino compound

What Type of Medicine is Orfenal (Orphenadrine)?

Orfenal is a prescription-only medication classified as a centrally acting skeletal muscle relaxant, containing the single active ingredient Orphenadrine. The drug is classified as a synthetic tertiary amino compound that also possesses prominent anticholinergic agent properties, defining its core mechanism and therapeutic utility. Orphenadrine is clinically recognized for its central action, which helps to modulate nerve activity related to muscle spasm. This differentiating feature ensures its primary use is systemic, focusing on the central nervous system (CNS) to achieve muscle relaxation. The drug's structural classification as a derivative of ethanolamine antihistamines is an important detail, lending context to its established anticholinergic effects.

Composition and Available Forms of Orfenal

The active component in Orfenal is Orphenadrine, a synthetic tertiary amino compound typically supplied in formulations utilizing either the citrate or hydrochloride salt. These specific salts allow for varied formulations appropriate for different routes of administration. In clinical practice, the preparation is available in two main dosage forms: for oral use as tablets, including formulations designed for extended-release to provide sustained action, and as a sterile parenteral injectable solution. The injectable form is prepared for administration via the intramuscular (IM) or intravenous (IV) route, offering a differentiating option for acute therapeutic interventions when rapid onset is necessary.

General Purpose and Action for Muscle Discomfort

The general purpose of Orfenal is the effective relief of acute, painful musculoskeletal conditions that are characterized by involuntary muscle spasm and significant stiffness. This is achieved because the medication's central action helps to damp down overactive nerve signals in the brain and spinal cord that trigger and sustain the painful muscle tightness. A typical use scenario involves providing symptomatic comfort during the recovery period following a musculoskeletal injury or acute strain. By modulating these central pathways, Orfenal assists in promoting physical comfort and restoring greater ease of movement, offering reliable symptomatic relief from the pain associated with uncontrolled skeletal muscle contraction.

Regulatory References

MedlinePlus, Orphenadrine Information

What side effects are possible with Orfenal?

The safety profile of Orfenal, containing Orphenadrine, is primarily defined by the mild anticholinergic action of the active ingredient, with adverse reactions generally associated with higher dosage.

Documented Adverse Reactions by System-Organ Class

The most commonly documented effects are often anticholinergic in nature, with dry mouth usually listed in regulatory documents as the first adverse effect to appear. Other potential effects are classified across several body systems:

Nervous System and Psychiatric Disorders: Drowsiness, dizziness, headache, weakness, hallucinations, and transient episodes of syncope (fainting). Mental confusion has been observed infrequently, particularly in elderly patients.
Gastrointestinal Disorders: Nausea, vomiting, and constipation.
Eye Disorders: Blurred vision, dilatation of pupils, and increased ocular tension.
Cardiac Disorders: Tachycardia (increased heart rate) and palpitation.
Renal and Urinary Disorders: Urinary hesitancy or urinary retention.

Serious Adverse Reactions and Safety Constraints

Official regulatory labels document serious adverse reactions including anaphylactic reaction, reported in rare instances following intramuscular injection. Aplastic anemia has been reported in very rare cases, although regulatory documents note that a causal relationship has not been established.

Safety restrictions are defined for patients with certain pre-existing conditions, where the drug is contraindicated, such as in cases of glaucoma, myasthenia gravis, stenosing peptic ulcers, and pyloric or duodenal obstruction. Use also requires caution in patients with pre-existing cardiac conditions, including cardiac decompensation, coronary insufficiency, and cardiac arrhythmias. Furthermore, the safety and effectiveness have not been established in pediatric patients, and use is generally not recommended for this age group.

Overdose and Emergency Response

Overdose and When to Seek Help

Official regulatory documentation classifies Orfenal (Orphenadrine) as toxic when taken in quantities exceeding prescribed doses. The reported range of toxicity is officially noted as variable and unpredictable, although the estimated minimum lethal dose for an adult has been reviewed as 2 to 3 grams.

Documented Overdose Manifestations

An overdose typically presents with severe anticholinergic effects, which impact multiple physiological systems. Documented cardiovascular signs may include tachycardia and palpitation. Effects on the central nervous system commonly involve hallucinations, profound mental confusion, and drowsiness. Other manifestations include ocular changes such as dilated pupils, blurred vision, increased ocular tension, and urinary involvement, specifically urinary retention. Regulatory labeling also notes that elderly patients may infrequently experience a higher degree of mental confusion at toxic dose levels.

Required Emergency Actions

Given the potential for severe outcomes, including seizure, collapse, and troubled breathing, immediate emergency medical attention must be sought if an overdose is suspected or confirmed. Management protocols require intensive monitoring. Treatment procedures include evacuation of stomach contents (when necessary) and the administration of charcoal at repeated doses. As no specific antidote is listed in the regulatory documents, treatment must consist of comprehensive supportive care for the emergent effects.

Therapeutic Uses of Orfenal

What Orfenal Treats: Main Uses and Benefits

Orfenal is commonly used as an adjunct therapy to provide symptomatic relief from symptoms related to physical discomfort associated with acute painful musculoskeletal conditions. It is relevant for easing pronounced symptoms such as involuntary muscle spasm, resultant stiffness, and mild-to-moderate pain following conditions like muscle strains and sprains. The drug is commonly used across conditions presenting with acute episodes when supportive symptom management is appropriate.

The medication is also applied in specialized neurological contexts to manage specific symptoms of tremor and stiffness observed in conditions such as Parkinsonism. It is a supportive measure, relevant when symptoms become temporarily overwhelming and interfere with daily functioning. The medication provides support that helps ease the overall symptom burden and contributes to improved day-to-day comfort.

“Orfenal helps address symptom clusters that may become intense or disruptive, supporting the patient during difficult episodes.”

Quick Fact: Relief for Acute Muscle Spasm

Regulatory References

NIH MedlinePlus overview of Orphenadrine uses

Eligibility and Restrictions for Use

Who Can and Cannot Use Orfenal?

Orfenal (Orphenadrine) eligibility is strictly defined by regulatory authorities and centers on absolute restrictions, primarily due to the drug’s anticholinergic effects. The criteria define which populations may use the medicine and which are officially excluded.

Absolute Contraindications

Orfenal must not be used by patients diagnosed with specific pre-existing conditions. These include glaucoma, myasthenia gravis, or any form of gastrointestinal or urinary tract obstruction (such as pyloric/duodenal obstruction, stenosing peptic ulcers, or prostatic hypertrophy). The medicine is also contraindicated in individuals with cardio-spasm or known hypersensitivity to the drug.

Age-Group and Conditional Use

The safety and effectiveness of Orfenal have not been established for the pediatric age group, and therefore, it is not recommended for use in individuals under 12 years of age. Use is subject to caution in older adults and in patients with pre-existing heart conditions, such as tachycardia, cardiac decompensation, or coronary insufficiency.

Reproductive Status and Monitoring

For pregnant women, Orfenal is classified as Pregnancy Category C, meaning its use should be administered only if clearly needed. Its use during lactation requires caution as it is not known if the drug is excreted in human milk. For prolonged continuous therapy, regulatory documents recommend periodic monitoring of blood, urine, and liver function because long-term safety has not been established.

What should I know about interactions with other medicines?

Interactions with other medicines and products

Official regulatory information for Orfenal (Orphenadrine) focuses on two major pharmacodynamic interaction classes and one key pharmacokinetic mechanism.

Pharmacodynamic Interactions

Additive Central Nervous System (CNS) Depression: Co-administration with other CNS Depressants—including other muscle relaxants, opioids, hypnotics, and sedatives—may result in an additive CNS depressive effect, increasing the risk of drowsiness. Alcohol is also documented to potentiate these depressant effects.
Anticholinergic Potentiation: Combining Orfenal with other Anticholinergic Drugs (e.g., certain antidepressants or antihistamines) may lead to an enhancement of effects, increasing the potential for anticholinergic-related outcomes.
Substance-Specific Caution: The combination of Orfenal with Propoxyphene is associated in regulatory text with reports of confusion, anxiety, and tremors, leading to a recommendation to discontinue or reduce the dosage of one or both agents.

Pharmacokinetic Interactions

Enzyme Induction: Orfenal is documented to induce enzymatic systems that affect the metabolism of certain co-administered medicinal products. This action may result in the reduced exposure or decreased plasma levels of substrates such as Steroidal Contraceptives and Griseofulvin.

Population Considerations

Official labeling notes that elderly patients may be particularly sensitive to the drug's anticholinergic activity, which can heighten the clinical relevance of anticholinergic potentiation interactions.

Mechanism of Action

Orfenal (Orphenadrine) exerts its pharmacodynamic effects primarily within the Central Nervous System (CNS) by engaging three distinct signaling domains. It acts as a nonselective antagonist at muscarinic acetylcholine receptors in central motor regions. This interaction alters the ratio of cholinergic to other neurotransmission in motor pathways, resulting in the modulation of central motor reflexes that govern muscle tone. The drug also functions as a non-competitive antagonist at the N-methyl-D-aspartate (NMDA) receptors. By blocking the associated ion channel, it results in the inhibition of excessive excitatory nerve impulse transmission mediated by glutamate. Additionally, Orfenal inhibits the reuptake of norepinephrine, increasing its synaptic concentration. Coupled with antagonism at the Histamine H1 receptor, this activity influences central arousal pathways and descending nociceptive signaling.

Dosage and Administration Information

How Orfenal is Used: Official Administration Guidelines

The administration of Orfenal (Orphenadrine) follows established protocols, establishing specific routes, dosage regimens, and procedural requirements for its use. The overall structure of use involves a course that typically transitions from acute initial injectable administration to sustained maintenance via the oral route.

Administration Scope	Instruction
Routes	Oral (immediate-release and extended-release tablets) or Parenteral (Intravenous [IV] or Intramuscular [IM] injection).
Standard Dosing	Oral ER: 100 mg per dose. Oral IR: 50 mg per dose. Parenteral: 60 mg per dose.
Frequency	Oral ER: Twice daily. Oral IR: Three times daily. Parenteral: May be repeated every 12 hours.
Timing	May be administered with or without food.

Specific Administration Protocols and Adjustments

The injectable route requires strict procedural adherence: the IV dose must be injected slowly over approximately five minutes, and the patient should remain supine for 5 to 10 minutes following injection. Oral forms also have mandatory instructions: the extended-release tablet must be swallowed whole and must not be crushed, broken, or chewed to ensure proper drug release.

Dosing for continuous long-term use has not been definitively established. For older adults, it is indicated that dose reduction should be considered due to potential increased susceptibility to certain effects. Use is not recommended for pediatric patients under 12, as safety and effectiveness in this group have not been established.

Recent Clinical Evidence

Research Evidence / Overview of Studies

Overview of Clinical Research

Clinical studies have investigated the drug's mechanism of action. Clinical studies evaluated the drug's effect on measured outcomes for pain and swelling.

Research investigated the pharmacokinetics of the drug (how the body absorbs, distributes, and eliminates it).
Some clinical studies included participants with pre-existing liver conditions to investigate various effects.
The scope of research reviewed did not include dedicated studies on interactions with other treatments.

Studies on Combined Therapy

Studies investigated the combination of this drug with physiotherapy. The goal of this research was to examine whether combined modalities affect patient mobility metrics.

Studies compared the effects of the drug in combination therapy versus monotherapy (using the drug alone). Some clinical studies recorded the time to observed changes in participants. Comparative studies involving other commercial treatments have not been reviewed here.

Research on Tolerability

Clinical trials included studies focused on the drug's tolerability in adult populations. Tolerability assessments measure how well a patient population can withstand any side effects or discomfort associated with the drug. Some studies evaluated specific pain symptoms, including the timing and intensity of those symptoms.

Key Studies & References

Frequently Asked Questions (FAQ)

Common questions about Orfenal (FAQ)

Q: Are there any common over-the-counter medicines that interact with Orfenal?

Official documentation indicates that Orfenal may have enhanced effects, such as increased drowsiness, when combined with other medicines that have anticholinergic or central nervous system (CNS) depressant properties. These properties are present in many common over-the-counter products, including certain cold remedies or sleep aids. Official patient information suggests that patients share all medications, including OTC products, with a healthcare professional.

Q: What is the difference between Orfenal and a placebo in clinical trials?

Research studies have examined the effects of Orfenal in comparison to an inactive substance (placebo). Evidence from research suggests that the medication demonstrated a statistically significant change in measured outcomes for acute musculoskeletal pain and stiffness compared to placebo.

Q: What should I do if I notice a new symptom while taking Orfenal?

According to official patient information, if you notice any new or unusual problems while using this medication, official guidance advises contacting a healthcare professional. This allows for appropriate guidance regarding the symptom and the course of treatment.

Q: What kind of studies have looked into the safety profile of Orfenal?

The safety profile of Orfenal has been examined through clinical trials and tolerability assessments. Tolerability studies focus on how well a patient population can withstand any side effects associated with the drug during use. These studies help define the known safety information in official documents.

Q: How quickly does Orfenal usually start working?

Studies on the extended-release oral tablet formulation show the onset of action has been demonstrated within about one hour of administration. For the injectable form, relief may begin more quickly, typically within five to ten minutes of being administered.

Q: How long do the effects of Orfenal typically last?

The extended-release oral tablet is specifically designed to remain active throughout a 12-hour dosing interval. This duration is consistent with its guidance for twice-daily administration.

Q: What happens if I miss a dose of Orfenal?

Official patient information indicates the missed dose is to be taken as soon as it is remembered. However, if it is close to the time for the next scheduled dose, the missed dose is typically skipped to avoid taking a double dose.

Q: If I take Orfenal for a long time, will it stop working?

Official documents note that the safety of continuous, long-term therapy has not been definitively established. For patients who undergo prolonged use, regulatory documents recommend periodic monitoring of specific body functions, including blood, urine, and liver function.

Q: Is Orfenal meant for short-term or long-term use?

The general purpose of the drug, as described in regulatory documentation, is for the symptomatic relief of discomfort associated with acute musculoskeletal conditions. The safety profile for continuous, long-term use has not been fully established.

Q: Can Orfenal affect my ability to sleep?

Official adverse reaction documents list drowsiness as a potential effect. Because the drug influences central arousal pathways, its activity may affect a person's ability to sleep.

Q: Does Orfenal require any special monitoring while being used?

For patients undergoing prolonged continuous therapy, regulatory documents recommend periodic monitoring of certain biological functions. This monitoring includes assessing blood, urine, and liver function to manage safety risks during extended use.

Q: Is Orfenal available over the counter in any country?

In the United States and other regions with similar regulatory structures, Orfenal is designated as a prescription-only medication. This classification means a prescription from an authorized healthcare professional is required to obtain it.

Q: Does Orfenal have effects on mood or mental health?

Adverse reactions documented in official regulatory texts include effects on the nervous system and psychiatric disorders. These effects can include hallucinations and mental confusion, which have been observed in certain patient populations.

Q: Are there different strengths of Orfenal available?

Yes, the medication is available in different strengths across its various formulations. These include 100 mg extended-release oral tablets, 50 mg immediate-release oral tablets, and 60 mg injectable solutions.

Q: What are the known risks of combining Orfenal with herbal remedies?

Official patient information advises that a healthcare professional should be informed of any herbal products being used. This sharing of information is used to assess the risk of potential interactions before use.

Q: Is it safe to take Orfenal if I have kidney issues?

Official labeling notes that the use of this drug in elderly patients, who may be more likely to have age-related kidney problems, is subject to conditional caution. For prolonged use, monitoring of urine and other functions is recommended.

Q: What is the average duration of treatment with Orfenal?

The drug is intended for use in the relief of discomfort associated with acute musculoskeletal conditions. The safety of continuous, long-term therapy has not been established in regulatory documentation.

Q: Why might a person's response to Orfenal be different from others?

Official labeling notes that certain populations, such as older adults, may be particularly sensitive to the drug’s anticholinergic activity. This means they may experience stronger effects compared to younger patients.

Q: Can I take Orfenal if I am driving?

Due to potential side effects such as drowsiness and dizziness, official warnings advise against driving or operating machinery until the patient knows how the medication specifically affects their ability to remain alert.

Q: What are the most commonly reported side effects of Orfenal?

According to documented adverse reaction reports, the most commonly experienced effect of the drug is dry mouth. Other frequently reported effects on the nervous system include drowsiness and dizziness.

How should Orfenal be stored and disposed of?

Storage and Disposal: Official Regulatory Information

Storage and Disposal Scope
Labeled storage temperature requirements: Store at Controlled Room Temperature, 20 C to 25 C (68 F to 77 F). Brief excursions between 15 C and 30 C (59 F and 86 F) are permitted.
Light/moisture protection requirements: Must be protected from light. The container must be kept tightly closed.
Child-protection storage requirements: Must be kept out of the sight and reach of children.
Packaging-related storage rules: Oral tablets must be dispensed in a tight, light-resistant container.

Official storage and disposal statements:

Store the product at Controlled Room Temperature and protect it from light.
Disposal should be handled through an official drug take-back program.
If a take-back program is unavailable, the medicine should be mixed with an undesirable substance (e.g., dirt, coffee grounds) and placed in a sealed container before discarding in the household trash.
The medication is not on the list of drugs recommended for flushing down the toilet.

Regulatory documents mandate that Orfenal is stored within a specific Controlled Room Temperature range to maintain its stability, while also requiring strict protection from light exposure. All formulations must be kept out of the reach of children. The official disposal procedures require using drug take-back programs or following specific household trash steps, as this product is not classified for disposal by flushing.

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

Available in countries:

Malta

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