Products
Capsaicin cream at 0.025% or 0.075% (also 0.1%) is not registered as a finished drug in many countries, unlike other countries. It is produced as an extemporaneous preparation in pharmacies. The specialized trade can also order them from specialized service providers. On the other hand, patches containing the active ingredient (Qutenza) are approved as medicinal products.
Structure and properties
Capsaicin (C18H27NO3, Mr = 305.4 g/mol) exists as a white, crystalline, and odorless powder that is practically insoluble in water. The lipophilic vanillylamide is found in -species such as cayenne pepper of the Solanaceae family.
Production
Manufacturing instructions for the cream can be found, for example, in the DMS and the NRF. Various bases are used. Percentages are by mass percent (m/m). Pure capsaicin is toxic if swallowed, may cause skin irritation, allergic reactions, severe eye damage, and respiratory problems and irritation. Therefore, protective gloves made of nitrile, a protective mask, safety goggles and protective clothing should be worn during production. The powder should be worked with under a fume hood. The complete information is listed in the safety data sheet. The cream is stored in a refrigerator.
Effects
Capsaicin (ATC N01BX04) has initial warming, circulatory, irritant, burning, vasodilator, and pruritic properties. On the other hand, with prolonged use, it has analgesic, antinociceptive and antipruritic effects. The drug target of capsaicin is TRPV1 (Transient Receptor Potential Vanilloid 1), a non-selective cation channel that is also activated by heat and protons. In skin, TRPV1 is found in the cell membrane of sensory nerve fibers. Capsaicin is an agonist to this ion channel. It activates TRPV1-expressing nociceptors and stimulates the release of neuropeptides such as substance P. This initially leads to the adverse effects mentioned. This is followed by a refractory period with reduced sensitivity and, after repeated applications, permanent desensitization. This causes insensitivity of the nerve fibers to various stimuli and leads to pain relief.
Indications for use
Indications for use include:
- For the treatment of peripheral neuropathic pain (nerve pain, neuralgia) in adults. These include postherpetic neuralgia and diabetic neuropathy.
- For the symptomatic treatment of pain associated with muscle, joint and back pain.
- Other nerve disorders (neuropathies).
- Idiopathic pruritus.
Dosage
According to the doctor’s instructions. A small amount of cream is applied to the affected areas three to four times a day. It is rubbed in lightly without leaving any residue on the skin. The dosing interval should be at least 4 hours. Hands should be washed immediately after administration. Or nitrile gloves or other aids are used for application. Local adverse effects such as a burning sensation and pain may occur initially and are normal. Do not inhale near the cream because capsaicin irritates the respiratory tract. The cream should not be used on injured, irritated or diseased skin. Do not bring into contact with eyes or mucous membranes. Do not use under occlusion. Do not take hot baths or showers before or after administration as this will increase the adverse effects.
Contraindications
- Hypersensitivity
- Application to injured, irritated or diseased skin.
- Contact with the eyes, respiratory tract or mucous membrane.
- Pregnancy, lactation
- Babies, children
Full precautions can be found in the SmPC.
Interactions
Interactions are possible with other topically administered drugs that irritate the skin.
Adverse effects
The most common possible adverse effects include local reactions such as a burning sensation, pain, redness of the skin, and itching. These symptoms usually subside after a few days. Capsaicin may cause a temporary increase in blood pressure and irritate the respiratory tract.
