Definition and examples
The duration of therapy or treatment defines the period of time during which a drug is administered preventively or therapeutically. The shortest duration of therapy occurs with a single dose. This involves a single administration of a drug without repetition. An example of this is the antifungal drug fluconazole for the treatment of certain fungal infections (e.g. vaginal mycosis). The “morning-after pill” is also taken once if vomiting does not occur. Some antibiotics can be given as a single dose, such as fosfomycin for cystitis. However, they are usually taken about two to three times a day for a few days to two weeks. The duration of therapy can also be several weeks or months. Examples include nail fungus treatment with topical products or hepatitis C therapy. Many medications are taken only as long as symptoms persist, for example, cough-irritant medications for irritable coughs or pain relievers for headaches. The antiestrogen tamoxifen is taken daily for 5 or 10 years for adjuvant therapy of breast cancer. And finally, there are also medications that must be administered for the rest of the patient’s life after diagnosis, such as insulins for type 1 diabetes. This is also true for agents for COPD, cystic fibrosis, multiple sclerosis, dementia, or Parkinson’s disease.
Influencing factors
The dosing interval may differ relevantly and may be hours, a week, a month, or even as little as a year. The duration of therapy also has an impact on adherence. The shorter it is, the easier it is to adhere to the therapy regimen. The duration of therapy does not have to correspond to the duration of the disease. It may be necessary to continue taking the medication after the symptoms have subsided to allow healing or to prevent a relapse. The decisive question here is whether a disease is cured with a drug or whether only the symptoms are influenced. Adverse effects, risks and a potential for dependence can limit the duration of therapy. This applies, for example, to topical glucocorticoids, which cause long-term damage to the skin, or to sleeping pills, which are addictive. Side effects can be prevented by taking breaks from therapy. Non-steroidal anti-inflammatory drugs should also be taken for a short time if possible. Cytostatic drugs are often used in therapy cycles. The duration of therapy also depends on regulatory factors. For example, if a drug has only been studied for three months in clinical trials, it is possible that regulators will only approve it for that duration. Whenever possible, information on treatment duration should be based on clinical evidence. For self-medication, the duration of therapy is often limited for safety reasons. Commercial aspects may also play a role because the authorities exclude reimbursement over a certain duration. Finally, it should be regularly reviewed whether continuation of a treatment is medically justified.
