Usage
- Oxyphenonium is prescribed for the treatment of peptic ulcers and to prevent muscle spasms in the gastrointestinal tract. It is also used to relieve visceral spasms in other internal organs such as the bladder, uterus, or rectum. It is effective in managing conditions marked by excessive smooth muscle activity and secretion within the gastrointestinal system. For example, it can help reduce painful cramps linked to irritable bowel syndrome (IBS) and decrease gastric acid secretion in peptic ulcer disease.
- Pharmacological Classification: Anticholinergic, Antimuscarinic agent, Antispasmodic.
Alternate Names
- International/Regional Variations: Oxyphenonium bromide.
- Brand Names: Antrenyl, Ulpane, Antrenyl Duplex.
How It Works
- Pharmacodynamics: Oxyphenonium bromide, an anticholinergic drug, diminishes the effects of acetylcholine (a neurotransmitter that stimulates muscles) by blocking muscarinic receptors on smooth muscle cells. It exerts a direct relaxing effect on these muscles, primarily within the gastrointestinal and urinary tracts. This action reduces gastrointestinal motility and gastric acid secretion and controls excessive pharyngeal, tracheal and bronchial secretions. This mechanism is the reason for its clinical efficacy in treating gastrointestinal spasm and hypermotility, cardiospasm, esophagospasm, gastroduodenitis, spastic constipation, pylorospasm, peptic ulcer, spasm associated with carcinoma. It also helps alleviate pain and spasm in the biliary and urinary tracts.
- Pharmacokinetics: The drug is well-absorbed from the GI tract after oral administration. Peak plasma concentration is reached approximately 1-2 hours post-ingestion. The elimination pathways are not fully elucidated, but both hepatic and renal routes are likely involved.
- Mode of Action: Oxyphenonium competitively antagonizes the action of acetylcholine at muscarinic receptors, particularly M1 and M3 subtypes. This inhibits the binding of acetylcholine, preventing activation of smooth muscle contraction and glandular secretion.
- Receptor Binding/Enzyme Inhibition/Neurotransmitter Modulation: As noted, the main mechanism is competitive antagonism of acetylcholine at muscarinic receptors.
Dosage
Standard Dosage
Adults:
- 5-10 mg, three to four times daily before meals. The dosage can be adjusted based on the patient’s response and the severity of the condition.
Children:
- 3-5 mg per day. Pediatric dosing needs careful adjustment according to the child’s weight and age.
Special Cases:
- Elderly Patients: Begin with a lower dose and adjust cautiously based on response and tolerance.
- Patients with Renal Impairment: Reduce the dosage to avoid accumulation. Consider the patient’s glomerular filtration rate (GFR) when adjusting.
- Patients with Hepatic Dysfunction: Reduce the dosage as there is a risk of impaired metabolism.
- Patients with Comorbid Conditions: Dose adjustment might be needed based on coexisting medical problems such as glaucoma, cardiovascular disease, or prostate enlargement.
Clinical Use Cases
- Dosage adjustments are needed for specific clinical situations. It is important to consult specialized resources and current guidelines for precise recommendations in these contexts.
- Intubation: Adjust dose to minimize secretions.
- Surgical Procedures: Used to decrease secretions and vagal reflexes.
- Mechanical Ventilation: Used to manage secretions.
- Intensive Care Unit (ICU) Use: Dosage varies based on specific patient needs.
- Emergency Situations: Adjust dosage as necessary based on the acute condition.
Dosage Adjustments
- Dose modifications are necessary for patients with renal or hepatic impairment. Consider genetic polymorphisms that could affect drug metabolism.
Side Effects
Common Side Effects
- Dry mouth, blurred vision, constipation, urinary retention, dizziness, headache, tachycardia.
Rare but Serious Side Effects
- Allergic reactions (e.g., rash, itching, swelling), acute glaucoma, severe urinary retention, paralytic ileus, confusion, hallucinations.
Long-Term Effects
- Potential complications from prolonged use include chronic constipation, urinary problems, and cognitive impairment, particularly in elderly patients.
Adverse Drug Reactions (ADR)
- Clinically significant ADRs needing immediate intervention include severe allergic reactions, cardiac arrhythmias, and signs of intestinal obstruction.
Contraindications
- Absolute contraindications: Hypersensitivity to oxyphenonium, myasthenia gravis, angle-closure glaucoma, urinary retention, paralytic ileus, and obstructive gastrointestinal diseases.
- Relative contraindications: Prostatic hypertrophy, cardiovascular disease, hyperthyroidism, ulcerative colitis, megacolon.
Drug Interactions
- Oxyphenonium interacts with numerous drugs including other anticholinergics, amantadine, some antihistamines, phenothiazines, and tricyclic antidepressants (TCAs).
- CYP450 interactions are not prominent.
- It can interact with antibiotics, anticoagulants, antihypertensives, and OTC drugs.
- Alcohol and smoking can potentially exacerbate certain side effects.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: C. While animal studies have shown potential fetal risk, adequate and well-controlled studies in pregnant women are lacking. Use only if the potential benefit justifies the potential risk to the fetus.
- The drug is excreted in breast milk, and its effects on nursing infants are not fully known. Exercise caution when administering to breastfeeding mothers.
Drug Profile Summary
- Mechanism of Action: Muscarinic receptor antagonist.
- Side Effects: Dry mouth, blurred vision, constipation, urinary retention.
- Contraindications: Glaucoma, myasthenia gravis, urinary retention, GI obstruction.
- Drug Interactions: Other anticholinergics, amantadine, antihistamines.
- Pregnancy & Breastfeeding: Use with caution.
- Dosage: 5-10 mg three to four times daily (adults); 3-5 mg daily (children).
- Monitoring Parameters: Heart rate, blood pressure, bowel movements, urinary output.
Popular Combinations
- Not typically used in combinations.
Precautions
- Pre-screen patients for contraindications.
- Caution in pregnant and breastfeeding women, children, and the elderly.
- Avoid alcohol and activities requiring alertness.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Oxyphenonium?
A: Adults: 5-10 mg three to four times daily before meals. Children: 3-5 mg daily, adjusted for weight and age.
Q2: What is the mechanism of action of Oxyphenonium?
A: It is an anticholinergic that blocks muscarinic receptors.
Q3: What are the common side effects of Oxyphenonium?
A: Dry mouth, blurred vision, constipation, and urinary retention are common.
Q4: What are the contraindications for Oxyphenonium?
A: Glaucoma, urinary retention, GI obstruction, and myasthenia gravis.
Q5: Can Oxyphenonium be used in pregnancy?
A: Use with caution if potential benefits outweigh potential risks. Category C. Consult specialist.
Q6: How should Oxyphenonium be administered?
A: Orally as tablets or liquid. IV administration may be used in certain scenarios.
Q7: Does Oxyphenonium interact with other medications?
A: Yes, it can interact with several drugs, including other anticholinergics. Review patient medications thoroughly.
Q8: What are the long-term effects of Oxyphenonium?
A: Chronic constipation, urinary problems, and cognitive changes are potential long-term effects.
Q9: What precautions should be taken when prescribing Oxyphenonium?
A: Screen for contraindications, start with a low dose in elderly patients, monitor patients with renal or hepatic impairment, advise patients about potential side effects.
Q10: How does renal impairment affect Oxyphenonium dosage?
A: Dosage reduction is often necessary to prevent drug accumulation in patients with renal impairment. The dose adjustment should be based on the degree of impairment (GFR).
