Table 1.
Representative advantages and disadvantages of different routes for drug delivery, as well as tissue targets and examples of therapies and delivery systems.
| Drug delivery route | Advantages | Disadvantages | Targets | Examples |
|---|---|---|---|---|
| Injections: intravenous (IV), intramuscular (IM), subcutaneous (SQ), depot | Applied to a large number of drugs | Rapidly cleared from body (IV) | Tissues with blood access (IV) | Chemotherapy (IV) |
| Rapid onset (IV) | Frequent injections required (IV) | Systemic | Vaccines (IM) | |
| Controlled release (IM, SQ) | Difficult to administer (IV) | Muscle (IM) | Insulin (SQ) | |
| As much as 100% bioavailability | Large gauge needles required (depot implant) | Hormones (Depot) | ||
| Lower burst release (depot implants) | Immunotoxicity (IV) | Hydrogels | ||
| Avoids reconstitution and/or suspension (depot implants) | Liver toxicity (IV) | Nanoparticles | ||
| Oral | High patient compliance | Low bioavailability | Systemic | Liquid medications |
| Ease of use | Variable absorption | Capsules | ||
| Lack of targeted systems | Pills | |||
| Degradation of drug in stomach and liver | Hydrogels | |||
| Variable adsorption in presence of food | Nanoparticles | |||
| Not amenable for macromolecule delivery | Microparticles | |||
| Transdermal | Painless administration | Low bioavailability | Systemic | Patches |
| Sustained and controlled release | Expensive | Skin | Microneedles | |
| Active control of continuing and discontinuing administration | Materials can be large, bulky | Creams | ||
| Reduced side effects | Variable absorption | Nanoparticles | ||
| High patient compliance | Incorrect dosages can be applied for some materials (creams) | Hydrogels | ||
| Pulmonary (i.e., inhalation) | Ease of use | Administration devices are large, bulky | Lungs | Aerosols |
| High bioavailability | Inconsistent delivery due to variation in patient technique | Systemic | Dry powders | |
| Rapid absoprtion and systemic uptake | Local lung toxicity and immunogenicity | Brain | Nanoparticles | |
| Direct access to lungs | Microparticles | |||
| Surgical implantation | Direct access to a range of diseased tissues | Potential infection due to surgery | Local, to a range of diseased tissues | Polymer implants |
| Reduced off target toxicity | Foreign body response and rejection | Microparticles | ||
| Requires surgical intervention | Materials can be large, bulky | Hydrogels | ||
| Potentially requires anaesthetics | Potentially requires immunosuppressing drugs | |||
| Time, cost, labor burden of procedure | ||||
| Mucosal routes: vaginal, nasal, buccal | Ease of use | Low bioavailability | Systemic | Films |
| Noninvasive | Variable absorption | Brain (nasal) | Sprays | |
| Self administerable | Local | Gels | ||
| Nervous system (nasal) | ||||
| Ocular: topical and injections | High patient compliance (topical) | High tear dilution and turnover rate (topical) | Eye | Eye drops |
| Noninvasive (topical) | Cornea acts as significant barrier (topical) | Injections | ||
| Self administerable (topical) | Toxicity due to high dosages (topical, injection) | Hydrogels | ||
| Direct delivery to retina (injection) | Retinal detachment, hemorrage, cataract (injection) | |||
| Sustained drug levels (injection) |