Your friend might have been given tamiflu to cure him of a bout of bird-flu, but did he end up with a stomach-ache too? Like tamiflu, many medicines have side-effects. In the future, we may have a new form of medicine called peptides that won't have any side-effects!
Why we need new drugs
Well, there are many reasons. One reason is that medicines are not a natural part of our body. We know how they go right, like we know penicillin kills bacteria, or paracetamol reduces fever. But we've got to accept that they don't work perfectly, yet.
That does not mean all medicines are unsafe. For example, tamiflu prevents viruses from escaping infected cells, so they cannot infect new cells. But if you've not eaten properly or took some other medicine, a tablet of Tamiflu might give you a mild stomach-ache. Taken properly, most drugs have no bad effects.
A more perfect drug
Why are drugs not perfect? It's because of chemistry.
Most of the molecules in our body are proteins, which do things like digesting food and taking oxygen to all cells of the body. Every medicine has its correct target protein. For example, tamiflu blocks the action of a protein, which is made by the flu virus. There is a spot on the protein which is important for the virus to work. Tamiflu goes and sits exactly in that spot, stopping the protein dead in its tracks. However, it doesn't sit very tightly, and in time gets knocked off. So you have to give more Tamiflu after some time to keep the protein under control.
As we know, proteins are made of hundreds of amino acids. Peptides are simply very small proteins, with 2-10 amino acids in them. The nice thing is that they can be designed in a laboratory to match the spot on the virus protein. So we design a peptide that can sit even more tightly on neuraminidase than tamiflu. Then we can reduce the dose the patient needs.
And when the virus has been finished off, the body can break the peptide down, and use its amino acids for something else. That's because peptides are quite natural to the body. So after acting as a medicine, it becomes food for the body!
There's a nice peptide that's good for your muscles, skin and joints. It's called gelatine, and there's a tasty way to have it - as jelly!
Are there any peptides in action?
There are quite a few. Some antibiotics like bacitracin and cyclosporine are actually peptides. Cyclosporine is used when someone receives an organ transplant; it helps prevent rejection of the foreign tissue by our body's immune system.
Milk peptides are a set of peptides made of just three amino acids each (and therefore a tripeptide). Some medical tests have shown that they help keep blood pressure at healthy levels. Leupeptin is another tripeptide, used to treat ear infections.
Glutathione (in picture) is an important peptide found in our bodies. It helps to clean up oxygen radicals, which are produced during normal activities of our body. These radicals can damage cells, causing pain, paralysis or poisoning. In patients who have low glutathione levels due to some illness (like AIDS), giving glutathione from outside can help. However, it gets digested in the stomach, so it can't be taken as a pill. Instead a peptide called N-acetylcysteine is given as a drug. The body converts this to glutathione.
Another peptide being tested in labs now is DSIP. Studies show that it can help people who are trying to get off their addiction to heroin or alcohol. It also helps fight narcolepsy, a condition in which the patient feels very sleepy throughout the day (Although we think giving less homework might have the same effect). And it also helps children recovering from the effects of chemotherapy (which is a way to treat cancer).
There are a lot more peptides being tested against all kinds of diseases, cancer and other disorders. If you choose to become a chemist, we hope you'll make a peptide medicine that'll solve a major medical problem!