What are the long term effects of using diclofenac patches?

Question

I wonder what the long term effects are of using diclofenac patches (e.g. one patch applied daily and kept for 24 hours positioned on the lateral epicondyle of the humerus). By long term I mean several months or more.

Answer 1

Pulled from News-Medical Life Science: All medications have a 'half life', meaning, the medication will only last so long - a specific numbers of minutes, hours, days, weeks, or months - in the body, dependent upon the medication and its designed delivery time.

The elimination half-life of a drug is a pharmacokinetic parameter that is defined as the time it takes for the concentration of the drug in the plasma or the total amount in the body to be reduced by 50%. In other words, after one half-life, the concentration of the drug in the body will be half of the starting dose.

With each additional half-life, proportionally less of the drug is eliminated. However, the time required for the drug to reach half of the original concentration remains constant.

In general, the effect of the drug is considered to have a negligible therapeutic effect after 4 half-lives, that is, when only 6.25% of the original dose remains in the body.

Illustrative Example

Taking a 100 mg dose of an intravenous drug with a half-life of 15 minutes as an example, the following is true:

1. 15 minutes after the drug administration, 50 mg of the drug remains in the body.
2. 30 minutes after the drug administration, 25 mg of the drug remains in the body.
3. 45 minutes after the drug administration, 12.5 mg of the drug remains in the body.
4. 1 hour after the drug administration, 6.25 mg of the drug remains in the body.
5. 2 hours after the drug administration, 0.39 mg of the drug remains in the body.

So, with respect to the Diclofenac Patch - it needs to be replaced every 24 hours - because at hour 24 only half the strength of the medication is available and 1/2 strength is not as effective to control pain/inflammation as full strength is designed to.

The heart medication Amiodarone has a half life of up to 142 days - this means that to be fully rid of this medication (after it is stopped completely) will take several MONTHS to clear the body. This is a problem is the patient is or develops a sentitivity (adverse rx or allergy) to this med.

Hope this helped.