What is Topical MS100 HR?

Topical MS100 HR: A Specialized Compounded Medication for Erythromelalgia

Topical MS100 HR is a compounded medication containing multiple active ingredients used primarily for treating erythromelalgia, with its main components likely including midodrine, amitriptyline, ketamine, clonidine, and gabapentin in a specialized base.

Composition and Mechanism

Based on the available guidelines, MS100 HR appears to be a specialized compounded topical preparation that likely contains:

1. Midodrine (0.2%) - An alpha-adrenergic agonist that helps reduce redness by causing vasoconstriction 1
2. Amitriptyline - A tricyclic antidepressant that provides pain relief when applied topically 1
3. Ketamine - An NMDA receptor antagonist that works synergistically with amitriptyline for pain relief 1
4. Clonidine - An α2-adrenergic receptor agonist that decreases excess central sympathetic outflow 1
5. Gabapentin - An anticonvulsant that provides topical pain relief 1

The "HR" designation likely refers to its specific formulation for heat-related or hyperemic conditions such as erythromelalgia.

Clinical Applications

The primary indication for MS100 HR appears to be:

• Erythromelalgia - A rare condition characterized by burning pain, redness, and increased skin temperature, typically affecting the extremities 1

According to the Mayo Clinic guidelines, this type of compounded mixture is used when:

• Single-agent topical treatments are insufficient
• Systemic medications need to be avoided
• Both pain and redness need to be addressed simultaneously 1

Administration and Usage

• Applied topically to affected areas
• May require prescription from a healthcare provider
• Must be prepared by a compounding pharmacy as it's not commercially available
• Typically applied several times daily as directed

Efficacy and Evidence

The evidence for multi-ingredient compounded topical preparations like MS100 HR is largely anecdotal:

"Other management strategies have only anecdotal evidence to support their use. For example, we occasionally use a mixture containing up to 5 ingredients by adding to the compounded amitriptyline-ketamine the topical formulations of 1 or more of the following: clonidine, gabapentin, and lidocaine." 1

The Mayo Clinic guidelines suggest that these compounded preparations may be beneficial in treating the pain and redness associated with erythromelalgia, though high-quality clinical trials are lacking.

Potential Side Effects

Common side effects may include:

• Local skin irritation
• Burning sensation upon application
• Redness at application site
• Potential systemic absorption (though minimal compared to oral medications)

Considerations and Precautions

• Should be used with caution in patients with known hypersensitivity to any of the components
• May not be suitable for pregnant or breastfeeding women due to limited safety data
• Cost may be a consideration as compounded medications are often not covered by insurance
• Availability depends on access to compounding pharmacies

Alternative Topical Treatments

If MS100 HR is unavailable or ineffective, alternative topical options for erythromelalgia include:

• For redness: Topical midodrine 0.2% alone, phenylephrine, oxymetazoline, timolol, or brimonidine 1
• For pain: Lidocaine patches or cream, capsaicin, or diclofenac gel 1

Conclusion

MS100 HR represents a specialized approach to treating complex pain conditions like erythromelalgia through a compounded topical preparation. While evidence for its efficacy is primarily anecdotal, it offers a potential option for patients who have not responded adequately to single-agent topical treatments or who cannot tolerate systemic medications.