Drug Interactions in Treating Rosacea

[Guide]

When rosaceans use drugs, whether prescription or non prescription, drug interactions are a concern when you take more than one drug to treat your rosacea. Whether the drug is oral, topical, tincture, toner, injection, or in whatever other form there can be drug interactions with other drugs, food or drink or some other unknown factor. First, let's be sure we agree on what a drug is so we are all on the same page and what a drug interaction is as well. 

Drug
"A drug is any substance that causes a change in an organism's physiology or psychology when consumed. Drugs are typically distinguished from food and substances that provide nutritional support. Consumption of drugs can be via inhalation, injection, smoking, ingestion, absorption via a patch on the skin, or dissolution under the tongue." [1]. 

Drug Interaction
So when taking a drug according to the definition above a drug interaction is defined as, "A drug interaction is a change in the action or side effects of a drug caused by concomitant administration with a food, beverage, supplement, or another drug." [2]

Treating Rosacea with Drugs
So the ideal setting is using one drug treatment for rosacea, i.e., topical metronidazole, the only drug interactions are with food, drink, and any other environmental factors to consider when using this treatment if you are not taking any other drugs at the same time. If, for example, you are taking aspirin or ibuprofen, what are the drug interactions to consider when applying the topical metronidazole? Also, what are the food and drink interactions to consider when taking topical metronidazole including any vitamins and supplements (considered food) you may be taking at the same time? For example, did you know that grapefruit juice can act as an enzyme inhibitor? St John's wort can act as an enzyme inductor. Garlic increases antiplatelet activity. Therefore, food or drink can interact with a drug.  However, if you are only using one drug to treat your rosacea you don't have to consider whether another drug is interacting with the topical metronidazole which is an ideal situation. If you are taking other drugs at the same time no matter what the reason you are taking the drug, these other drugs or food can interact with the topical metronidazole. [3]

When you take more than one drug treatment for rosacea at the same time, the drug interactions to consider are multiplied, and this increases when you add a third rosacea treatment and the complexity of the considerations of drug interactions increases with additional rosacea treatments. To sort out what is causing a particular drug interaction can be complex and difficult to resolve as you can imagine, when you should rule out all these different factors to consider. 

Synergism and Antagonism Factors
Synergism in medicine is the creation of a whole that is greater than the simple sum of its parts, i.e., the combined effect of taking two barbiturates is greater than taking each one at a time (combining the drugs leads to a larger effect than expected). The gold standard treatment for rosacea is a typical example of using synergism to treat rosacea. Another example is topical metronidazole and oral doxycycline together has a synergistic effect in treating rosacea. This is due to the synergistic effect of the two drugs interacting with each other. Sometimes synergism works out to the patient's benefit, but in some cases synergism can be negative which is what is termed Antagonism, "when synergy occurs at a cellular receptor level this is termed agonism, and the substances involved are termed agonists. On the other hand, in the case of antagonism, the substances involved are known as inverse agonists. The different responses of a receptor to the action of a drug has resulted in a number of classifications, such as "partial agonist", "competitive agonist" etc. These concepts have fundamental applications in the pharmacodynamics of these interactions." [2]

Pharmacodynamics and Pharmacokinetics
"Pharmacodynamics is the study of how a drug affects an organism, whereas pharmacokinetics is the study of how the organism affects the drug. Both together influence dosing, benefit, and adverse effects." [4] Pharmacists are trained in these two subjects and can answer more questions about any of your drug interaction questions better than most physicians. 

Drug Interactions to Consider When Treating Rosacea
In this section we will be considering what drug interactions need to be considered in treating rosacea, and this is a work in progress. If you have something to consider, why not volunteer and reply to this post. 

Antibiotics 
If you are using antibiotics to treat your rosacea, whether low dose or high dose, particularly one of the tetracycline class treatments, i.e., Oracea, doxycycline, minocycline, if you are taking at the same time as calcium, iron, antacids like Tums or Maalox, or foods such as milk, cheese, nuts, or medications or supplements that contain calcium or iron these are factors to consider whether the antibiotic will be successful or interfere with the treatment side effects. [5] 

more to come....

End Notes

[1] Drug, Wikipedia

[2] Drug Interaction, Wikipedia

[3] A partial list of drug interactions to consider with topical metronidazole are Antabuse (disulfiram), Anticoagulants, Dilantin (phenytoin), Hismanal (astemizole), Lithobid (lithium), Phenobarbital (Luminal and Solfoton), Tagamet (cimetidine), Vitamins, Alcohol, and the list continues. See Everyday Health Interaction with Metronidazole

[4] Pharmacodynamics, Wikipedia

[5] Antibiotics, Interactions, Everyday Health