Comments from Dr Peter Dvorak, Pharm.D.,DESS.,CTH.
The following documents (links) will help the health professional to determine which transdermal patches can be cut or modified. However, the context in which the patches will be used, should always be evaluated first.
In a hospital setting, the handling is carried out by qualified personnel according to an established protocol and in case of adverse reaction it is possible to quickly correct the problem. Therefore, it may be suggested to cut stamps that are theoretically breakable. The hospital environment provides a context where attempts can be made to individualize doses for reasons of efficacy, adverse effects, and research and teaching reasons. For these reasons, it is sometimes necessary to modify a galenic formulation.
In an outpatient setting when the patient handles the medication himself, the utmost caution is advised. Does the patient have sufficient dexterity and understanding for this type of manipulation? Is there a risk of contamination of instruments used such as scissors? Is there a risk of contact of the active ingredient contained in a piece of the patch with other people around the patient, such as spouse, children etc. The level of danger can be very high when using patches of narcotic analgesics such as fentanyl or buprenorphine and the risk of fatal accidental overdose is real.
There are currently two types of transdermal patches, the reservoir type and the matrix type which exists in three variants. The tank type is increasingly rare, given the risk of overdose in case of leakage. The latter can in no case be cut. Despite the documentation available below, before deciding whether to cut a patch, it is necessary to check what type it is, as manufacturers can change the type of formulation over time. In addition, it should never be assumed that if the original version is in matrix form, that the credits will automatically be in the same form and vice versa. The same is true between the different generic companies.
Regardless of the type of system, it is always possible to reduce the dose by proportionally decreasing the surface area of the transdermal patch in contact with the skin. To do this, the patient can leave part of the protective film under the patch or first apply a clear occlusive dressing such as Tegaderm® or Opsite® to the skin, then apply part of the patch to this dressing (the other part of the patch is glued directly to the skin). It is then necessary to apply an adhesive bandage (Micropore®, Hypafix®) on top to hold the patch in place. The patient should be advised that the patch should be discarded after the same period of wearing and that the unused portion of the patch cannot be re-glued to the skin afterwards. This technique avoids the aforementioned risks during the section of the stamp.
In conclusion, the professional must remember that any modification of a transdermal patch (or any galenic formulation) is an alternative of last resort, when other options have been exhausted. Professional judgment is essential for making this type of decision.