Traditional peptide drugs are unstable at room temperature and easily degraded in the body. Most of them are injections, especially intravenous injections. The main preparation type is freeze-dried powder. In recent years, with the development of various drug delivery technologies. Researchers have developed a variety of peptide drug formulation types.

Peptide Dosage Form

The peptide pharmaceutical preparations currently on the market include microspheres, implants, liposomes, microemulsion nanoparticles, etc.

1. Microspheres: Dissolve peptide drug molecules in high molecular materials or biodegradable polymers to achieve sustained drug release. Such as triptorelin microsphere preparations, the drug has a sustained release period of one month. Leuprolide sustained-release injection: injection once every 6 months.

2. Implant

There are two types of implants, natural polymers (such as gelatin, dextran) and synthetic polymers. Clinically, peptide drug implants include goserelin implants, which can be administered once every 28 days.

3. Liposome

The liposome preparation formed by the polypeptide drug encapsulated in the phospholipid bilayer can improve the stability of the drug, and has the advantages of good biocompatibility and low immunogenicity.

4. Microemulsion

The hydrophobic peptides are distributed in the oil-in-water (O/W) type dispersed phase, and the hydrophilic peptide preparations are of the water-in-oil (W/O) type. The use of microemulsion to wrap the peptides can protect the peptides from the acidic substances and enzymes in gastric acid, thereby improving the stability of the peptides and prolonging the half-life. For example, after cyclosporine is made into microemulsion, the oral bioavailability is significantly improved.

5.Nanoparticles

The nano drug-carrying system is targeted and can protect polypeptide drugs from proteases, thereby prolonging the half-life of polypeptide drugs. It is divided into polymer nanoparticles and solid lipid nanoparticles. In vivo animal experiments show that: RGD polypeptide is easily eliminated in the body, and chitosan nanoparticles can be used as a carrier of RGD polypeptide, effectively prolonging the time of RGD polypeptide in the body and enhancing its anti-tumor effect.

Route of Peptide Administration

Peptide drug administration is divided into two types: injection and non-injection administration. Injections include intravenous injection, subcutaneous injection, and intramuscular injection. Non-injection includes oral, nasal, eye, sublingual, skin, lung, rectal, and vaginal administration.

Compared with other modes of administration, patients tend to take oral administration, but due to the low oral bioavailability of polypeptide molecules, most of them are still injections. At present, a small number of peptide drugs can be administered orally, such as bacitracin, cyclosporine, linaclotide, etc. Most of these peptides are cyclic peptides with stable structures. The nasal cavity administration method is simple, and the capillaries in the nasal cavity are abundant, and the epithelial cells have the active absorption function, so the nasal cavity administration administration becomes one of the ideal administration routes. Clinically used nasal sprays are mainly nasal sprays, such as calcitonin and buserelin.

Due to the low enzyme activity of the skin, the drug will not be degraded. There are a variety of technologies that have been applied to the clinic, such as iontophoresis, microneedle technology, and ultrasound technology. Polypeptide drugs are not easy to pass through the skin, but with the application of these new technologies, some transdermal drug delivery technologies for polypeptides have also entered the phase II clinical research phase.