Medications used with Iontophoresis

Sarapin (P-Boc) and Dexamethasone are the two drugs needed for iontophoresis. These medications are prescription medications which Matrix does not sell. See your veterinarian for the medications. 

Sarapin (P-Bloc)

Sarapin is a regional anesthetic that provides non-sedating pain relief. P-Bloc is the veterinary label. The brand Sarapin has been on the market since 1931 and has no known side effects. Sarapin (for people) is known for relief of neuromuscular pain as an injectable with immediate effects and in some cases the pain relief lasts days or weeks. In horses (and dogs) this beneficial effect seems similar when phoresed for suspensory and check ligament injuries. P-Bloc is also very helpful for ringbone and bone spurs when phoresed for pain and to noticeably reduce the enlarged calcified areas.

2021 Update:  As of 2019 Sarapin is no longer being manufactured. Sarapin equivalents are available from compounding pharmacies.  At our store under books and media is current list of Sarapin sources. Beware of  veterinary product sites saying they have Sarapin or P-Bloc. 

Polarity: Positive – Sarapin


Dexamethasone is a corticosteroid and acts as an anti-inflammatory. It is necessary to use the 4mg/ml strength when phoresing (2 mg/ml is too weak).

Polarity: Negative – Dexamethasone

Horse Cocktail (for Iontophoresis)

The “horse cocktail” is a mixture of 4mg/ml Dexamethasone (optional: 40mg/ml Depo Medrol) for the negative polarity and Sarapin (P-Bloc) for the positive polarity. Saline Solution can be used if necessary to completely fill the drug-delivery pads. To learn more see the chapter on Iontophoresis in  “MicroCurrent for Horses and other vital therapies you should know” by Deborah Powell.