Which current type is appropriate for administering procaine hydrochloride iontophoresis for shoulder pain management?

For administering procaine hydrochloride iontophoresis, the most appropriate current type is a continuous monophasic current with the medication placed under the anode.

Procaine hydrochloride is a positively charged ion, and during iontophoresis, the goal is to use a current to drive the medication through the skin into the tissue. When using a monophasic current, one electrode serves as the anode (positively charged), and this is where the medication should be applied, allowing for effective delivery of the positively charged procaine ions into the tissue.

Continuous monophasic current ensures a steady flow that can promote effective transdermal drug delivery and minimize patient discomfort. This is particularly useful in managing shoulder pain, as consistent delivery of the medication can enhance its therapeutic effects.

In contrast, options that suggest placing the medication under the cathode are not suitable for procaine hydrochloride since the cathode would repel the positively charged drug, hindering its delivery. Additionally, using alternating or interrupted currents is not optimal for iontophoresis applications that rely on constant drug administration, as these types of currents could disrupt the consistent flow necessary for effective iontophoresis.