Doctors at a Dublin hospital report that fat tissue in the buttocks of patients, particularly obese women, may exceed the length of needles commonly used to deliver intramuscular injections:
Dr. [Victoria] Chan's research found 68% of the injections do not reach the muscles of the buttock. Dr Chan said her work suggested that patients were either not receiving the maximum benefit of a drug or receiving no benefit at all.
Professor Richard Guy, an expert in pharmaceutical sciences at Bath University, told the BBC News website the effectiveness of vaccines could be particularly compromised. They tend to be made up of large molecules that would only slowly diffuse out of fat tissue. He said: "Whether using longer needles is a practical solution, I'm not sure, as these are unlikely to be terribly popular."
Link to BBC News item.