New Drug Delivery Gives Off Peptide to Human Body; What Makes It Different From Protein?

One of the first entirely novel drug delivery microencapsulation techniques in decades is described in a recent study from the University of Michigan.

According to NewsMedical.net, drugs like peptide therapies can be microencapsulated in biodegradable polymers and released over time in the body.

Peptides are short sequences of amino acids found in the body and contain messengers, growth factors, and well-known hormones like insulin. Peptide medications are seldom taken by mouth and must be injected due to their size and structure. One option to shorten the time between injections is to use microencapsulation.

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393282 04: A digital representation of the human genome August 15, 2001 at the American Museum of Natural History in New York City. Each color represents one the four chemical compenents of DNA.

Peptides vs. Protein: The Difference

Proteins and peptides are key biological components that carry out vital tasks in cells. Proteins, for example, give cells their form and respond to signals from the extracellular environment. Peptides serve an important function in controlling the activity of other substances. Proteins and peptides are structurally similar, consisting of chains of amino acids bound together by peptide bonds (also called amide bonds). So, what makes a peptide different from a protein?

Size and structure are the primary differentiating characteristics, Britannica said. Proteins are larger than peptides. Peptides are often characterized as molecules containing between 2 and 50 amino acids, whereas proteins include 50 or more amino acids.

Furthermore, peptides have a less well-defined structure, unlike proteins, which can assume complicated conformations known as secondary, tertiary, and quaternary structures. Between peptides and proteins, functional differences can also be made.

Peptides as a Medication

Research co-author Steven Schwendeman, professor of pharmaceutical sciences and biomedical engineering, said in a ScienceDaily report that encapsulating peptide medications within resorbable polymers often employed as dissolving sutures is one slow-release delivery approach for peptide therapeutics.

However, developing polymer dosage forms for the administration of specific peptide medications has proven problematic due to the present methods for microencapsulating the peptide molecules in the polymer, which need organic solvents and complicated manufacturing.

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About 10 years ago, the researchers discovered that peptides might spontaneously attach and enter the polymer from water to microencapsulate the peptide without using an organic solvent.

The group demonstrated that the concept might work at the time, but it was not yet financially viable.

Schwendeman said the work illustrates that this technique may easily manufacture similar or even better injectable biodegradable polymer particles than existing commercial solutions, giving one of the first wholly novel microencapsulation technologies in decades.

Schwendeman and colleagues realized that if they first synthesized the polymer, then equilibrated the peptide with the polymer microspheres in water under appropriate circumstances, they could get a remarkably comparable result to the traditional organic-solvent-based approach of drug encapsulation.

How Researchers Experimented with Peptides

The researchers discovered that leuprolide encapsulated in this way produced peptides in the lab for over 56 days and inhibited testosterone levels in rats in the same way that a one-month Lupron Depot injection did. Prostate cancer, endometriosis, and other disorders are treated with leuprolide injections.

This encapsulation approach is compatible with several different peptide medications now on the market and those that have just been authorized or are in development, according to Schwendeman.

The team is currently working on improving the capacity to encapsulate other types of peptides and other big molecular medications and creating a second strategy for remotely loading pharmaceuticals into the polymer, which is aimed at fragile proteins.

Researchers published their study, "Efficient aqueous remote loading of peptides in poly(lactic-co-glycolic acid)," in Nature Communications.