Polymers are compounds with high molecular masses formed by
monomers. In Greek, the word poly means 'many', and meros means 'units or
parts'. Polymers play a major role in the development of drug delivery
technology by releasing two types of drugs, like; hydrophilic and hydrophobic,
in a synchronised manner and constant release of formulations over extended
periods. There are numerous advantages of polymers acting as an inert carrier to
which a drug can be conjugated, for example, the polymer improves the
pharmacokinetic and pharmacodynamic properties of biopharmaceuticals through
various ways, like; plasma half-life, decreases the immunogenicity, build ups
the stability of biopharmaceuticals, improves the solubility of low molecular
weight drugs, and has a potential of targeted drug delivery. However, they have
their own limitations, such as the natural polymers are most abundant and
biodegradable, but are difficult to reproduce and purify. Synthetic polymers have
high immunogenicity, which prevents their long-term usage. Non-biodegradable polymers
need to be sugary after they release the drug at the targeted site. The general
characteristic features that make the polymer a potential candidate for drug
delivery include: safety, efficacy, hydrophilicity, absence of immunogenicity,
biological inactivity, sufficient pharmacokinetics and presence of functional
groups for covalent conjugation of drugs, targeting moieties or formation of
copolymer.
Characteristics of an Ideal Polymer
1. Low density.
2. Low coefficient of friction.
3. Good corrosion resistance.
4. Good mould ability.
5. Excellent surface finish can be obtained.
6. Can be produced with close dimensional tolerances.
7. Economical.
8. Poor tensile strength.
9. Low mechanical properties.
10. Poor temperature resistance.
11. Can be produced transparently or in different colours.