Racemethionine

Usage

Racemethionine is primarily used to acidify urine. This helps to relieve skin irritation in adults with incontinence and infants with diaper rash. It also helps control strong urine odor by lowering urinary pH, which reduces the volatilization of ammonia. It can be used as an antidote for acetaminophen overdose, although N-acetylcysteine is generally preferred.

• Pharmacological Classification: Urinary acidifier, antidote (in acetaminophen overdose)

• Mechanism of Action: Racemethionine is metabolized to sulfate and other acidic byproducts. These byproducts increase the acidity of the urine. The exact mechanism by which it relieves skin irritation isn’t fully understood but is associated with decreasing the pH.

Alternate Names

• Methionine
• DL-Methionine
• ME-500

How It Works

• Pharmacodynamics: Racemethionine’s primary effect is to lower urinary pH, making the urine more acidic. This helps prevent the breakdown of urea to ammonia, minimizing skin irritation and odor associated with alkaline urine. In acetaminophen overdose, it may help by replenishing hepatic glutathione stores, but this effect is secondary to N-acetylcysteine.

• Pharmacokinetics: Racemethionine is absorbed orally. The specific pharmacokinetic parameters (absorption rate, bioavailability, metabolism, and elimination half-life) are not precisely defined in available literature. It is known that the drug is metabolized in the liver and primarily eliminated renally.

• Mode of Action/Receptor Binding/Enzyme Inhibition/Neurotransmitter Modulation: The primary mode of action in acidifying urine is through the production of acidic metabolites in the liver. It does not have specific receptor binding, enzyme inhibition, or neurotransmitter modulation properties related to this primary use.

• Elimination Pathways: Racemethionine and its metabolites are primarily excreted through renal pathways.

Dosage

Standard Dosage

Adults:

• Capsules/Tablets: 200-500 mg three to four times a day.
• Oral Solution: 2⅔ teaspoonfuls (200 mg) three to four times a day.

Children:

• Oral Solution:

  • 14 months: 2⅔ teaspoonfuls (200 mg) three or four times a day.

  • 6-14 months: 1 teaspoonful (75 mg) four times a day for three to five days.
  • 2-6 months: 1 teaspoonful (75 mg) three times a day for three to five days.
  • < 2 months: Dosage must be determined by a physician.

• Capsules: 200 mg mixed with formula or milk/juice once daily, typically in the evening.

Special Cases:

• Elderly Patients: No specific dosage adjustments, but monitor for adverse effects.
• Patients with Renal Impairment: Caution advised; dose adjustment may be necessary.
• Patients with Hepatic Dysfunction: Contraindicated in severe liver disease. Use with caution in mild to moderate hepatic impairment; dose adjustment may be necessary.
• Patients with Comorbid Conditions: Use with caution in patients with metabolic acidosis.

Clinical Use Cases

Dosage recommendations for specific medical settings like intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations, are not specifically addressed in available resources. Dosage recommendations are based on the indications mentioned above (primarily for acidifying urine).

Dosage Adjustments:

Dose modifications are based on patient-specific factors like renal/hepatic dysfunction, metabolic disorders, or genetic polymorphisms affecting drug metabolism, though precise recommendations are not detailed in available literature. Clinical judgment is required.

Side Effects

Common Side Effects:

• Drowsiness
• Nausea and vomiting

Rare but Serious Side Effects:

Limited information is available regarding severe or rare side effects.

Long-Term Effects:

No information is available on chronic complications from prolonged use.

Adverse Drug Reactions (ADR):

No specific, clinically significant ADRs requiring immediate intervention are detailed in readily available resources.

Contraindications

• Severe liver disease.
• Metabolic acidosis.
• Hypersensitivity to racemethionine.

Drug Interactions

Limited information is available on specific drug interactions beyond those mentioned in source material. Interactions with commonly prescribed medications, OTC drugs, supplements, and food (including alcohol, smoking, grapefruit juice) require further consultation with relevant resources or specialist advice.

Pregnancy and Breastfeeding

Insufficient data exist regarding the safety of racemethionine during pregnancy and breastfeeding. Consult specialized databases for detailed information.

Drug Profile Summary

• Mechanism of Action: Acidifies urine by producing acidic metabolites.
• Side Effects: Drowsiness, nausea, and vomiting.
• Contraindications: Severe liver disease, metabolic acidosis, hypersensitivity.
• Drug Interactions: Limited information available.
• Pregnancy & Breastfeeding: Insufficient safety data.
• Dosage: See Dosage section above.
• Monitoring Parameters: Monitor urine pH, renal and liver function tests (especially in patients with pre-existing conditions).

Popular Combinations

• Paracetamol + Racemethionine: This combination is available commercially and is primarily used for mild to moderate pain and fever.

Precautions

• General Precautions: Screen for pre-existing liver or kidney disease, metabolic acidosis, and allergies.
• Specific Populations: See special cases under Dosage.
• Lifestyle Considerations: Limited data on impact of alcohol, diet, or smoking. Driving restrictions are unlikely.

FAQs (Frequently Asked Questions)

Q1: What is the recommended dosage for Racemethionine?

A: See the detailed dosage guidelines provided above, including information for adults, children, and special populations.

Q2: What are the primary uses of Racemethionine?

A: Racemethionine is primarily used to acidify urine, relieving skin irritation associated with incontinence and diaper rash, and controlling urine odor.

Q3: How does Racemethionine work to acidify urine?

A: It’s metabolized to sulfate and other acidic byproducts, which increase urine acidity.

Q4: Is Racemethionine safe for patients with liver disease?

A: It is contraindicated in severe liver disease and should be used with caution in mild to moderate hepatic impairment.

Q5: Are there any significant drug interactions with Racemethionine?

A: Specific information on drug interactions is limited. Refer to drug interaction databases and resources for further information.

Q6: Can Racemethionine be used during pregnancy or breastfeeding?

A: There is insufficient data regarding the safety of racemethionine during pregnancy and breastfeeding. Consult specialized databases and clinical guidelines before prescribing or using it in these situations.

Q7: What are the common side effects of Racemethionine?

A: Common side effects can include drowsiness, nausea, and vomiting.

Q8: Is Racemethionine effective for acetaminophen overdose?

A: It can be used in acetaminophen overdose, but N-acetylcysteine is the preferred treatment.

Q9: How is Racemethionine administered?

A: Racemethionine is available in oral forms, including capsules, tablets, and oral solution.

Q10: Does Racemethionine interact with food?

A: Specific data regarding food interactions are limited. However, it is generally recommended to take Racemethionine with or just after meals.