Many medications have the problem of going where they shouldn't and causing undesirable side effects.  Painkillers can cause nausea, psychiatric medications may cause dissociation, and chemotherapy frequently destroys healthy cells. A group of researchers from Stanford Medicine is now nearing a breakthrough solution: a non-invasive method that can precisely deliver medications down to a few millimeters anyplace in the body.

The system uses nanoparticles to encapsulate drugs along with ultrasound to unleash the drugs at their intended destinations.

Radiology professor Raag Airan, senior author of the study that appeared in Nature Nanotechnology, explained that this could "maximize the therapeutic effect and minimize the off-target effects” of many drugs we use today.

The researchers tested their approach using ultrasound-responsive drug delivery nanoparticles on rats with two drugs. First up was a ketamine dosage that was precisely delivered using nanoparticles and stabilized with a sugar solution (specifically 5% sucrose), reports NewAtlas.

Three times as much ketamine was detected in a specific area of the brain as in other areas when it was administered by injection and subsequently activated with a low-intensity ultrasound pulse directed at that area using a specialized transducer, suggesting that the medication was released precisely.

In order to successfully reduce the rats' nervous behavior, the researchers also attempted delivering ketamine specifically to the prefrontal brain, which controls emotional stress. That suggests that this technique could assist medical professionals in treating human depression with ketamine in a similar way without the dissociative side effects that this often causes.

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Using a topical anesthetic, the scientists also employed this method to block sciatic nerve discomfort in one rat leg. The wonderful thing about this is that it can allow patients to have injections in other parts of their bodies, where getting a jab wouldn't hurt too much. Then, utilizing concentrated ultrasound, the anesthetic can activate at the treatment location.

In 2018, Professor Airan investigated the use of ultrasound technology for drug delivery as well. However, his method was not ideal because the drug-loaded nanoparticles he was using were unstable at body temperature, causing the medication to leak everywhere.

In order for the ultrasound to interact with the nanoparticles specifically, he refined his system by substituting the shell material for the nanoparticles and using a sugar solution to make sure their acoustic impedance – a measure of how easily sound waves pass through a material—was different from the medium they were passing through.

The team is currently working to set up the first human trial with this system, which will see the use of ketamine to target a patient’s emotional experience of chronic pain.