Ask the Pharmacist

Q: How long will it take for this medication to work?

A: This is a question every patient should know prior to commencing a new treatment and yet is often overlooked in the initial counselling which tends to focus on how to take a drug and possible side effects associated with it.

Many patients assume that the timing of their next doctor's appointment should roughly coincide with the drug’s onset of action but that is frequently incorrect as physician appointments are often based on an always near-full schedule that does not leave a lot of flexibility for the doctor.

While it would be impossible in a single article to go through every drug or even every class of drugs to give you some idea of when the drug should be “kicking in” for the average patient, we will review some of the major classes at least.

It seems appropriate at this time of year to start with antibiotics, given all the infections that are wreaking havoc on so many of us.

The answer to this question depends on factors such as the recipient’s general level of health, the antibiotic chosen (most start to kill bacteria within a few hours at most, but this does not correspond to symptom relief as of yet) and the type of infection being treated (urinary tract infections often respond quickly while infections in areas where it is hard for antibiotics to penetrate, such as a sinus or prostate, may take significantly longer to feel better), but the general rule of thumb is that you should start to see improvement in your symptoms within 72 hours of starting the drug.

Certainly if you’re into day five of a treatment and you feel just as lousy as you did before you saw your doctor, then it is more than appropriate to get reassessed even if you have a few days left on your prescription.

Another group of medications that most people are extremely interested in knowing just how quickly they will kick in, are the pain killers, for obvious reasons. Most of the common pain killers we use for acute pain (i.e. short-term pain, such as a headache or a sports injury) should start to relieve our discomfort anywhere from 15 minutes to an hour after taking the drug.

This group of drugs includes Tylenol/acetaminophen (usually about 30 minutes to work), the anti-inflammatories such as Advil/ibuprofen and Aleve/naproxen (30 minutes to an hour), or the opioid drugs such as Oxycocet/oxycodone (closer to 15 minutes).

One factor that can affect how quickly these work is the dosage form of the drugs. Gel capsules and liquids, which are usually a little more expensive, tend to work a few minutes quicker since they do not have to dissolve first before entering your blood stream. This can be critical in treating conditions, such as menstrual cramps and migraines, where the quicker the pain is dealt with the more likely the medication is to work.

Conversely, long-acting pain killers, such as the fentanyl patch or the “Contins,” should be at full therapeutic effect within 72 hours, allowing doctors to make adjustments relatively quickly for inadequate pain control.

For blood pressure drugs, the class of drug used determines how quickly the patient can accurately be assessed, although if the blood pressure is extremely high (thereby putting the affected at risk of a cardiovascular event), a physician may well bring you back after only a few days.

Thiazide diuretics, such as hydrochlorothiazide, should be given at least a week before assessing their effectiveness. The potassium-sparing diuretic, spironolactone, is different in that it can take four to six weeks before its full effect on blood pressure can be known.

The impact of the calcium channel blockers, such as amlodipine or diltiazem, can be accurately assessed within just a few days (four or five for amlodipine and less than that for the rest of the class), and the beta-blockers (such as metoprolol and bisoprolol) tend to work just as quickly.

As for the classes that lower blood pressure by impacting the effects of the chemical angiotensin, including the ACE inhibitors (angiotensin converting inhibitors such as Coversyl and ramipril) and the “ARBs” (angiotensin receptor blockers such as Micardis or Avapro), they exert most of their effect within a couple of days but may take up to three weeks for maximal effect.

Lastly, we thought we would go through a quick run down on the diabetic drugs as many people pick up a blood glucose monitor when they are prescribed their first sugar-lowering drug and should be given some idea as to when they should notice a response.

In general, if the drug is injected, such as any of the short- or long-acting insulins or the short-acting GLP-1 Agonists (like Victoza or Byetta), the effects can be measured within hours (or even minutes for the short-acting insulins) of the first dose although most physicians like to wait at least three days before reassessing the prescribed dose.

The only pills that act this quickly are the sulfonylureas (gliclazide) and the meglitinides such as repaglinide. Metformin, which is the most common drug given to non-insulin dependent diabetics, should be reassessed after one to two weeks which also applies to the DPP-4 inhibitors (the “gliptans” such as sitagliptan and saxagliptan) and the newer SGLT-2 inhibitors (the “flozins” which include canaglifozin and empagliflozin).

Finally, the true impact of the long-acting GLP-1 agonists (such as Trulicity) can take a few weeks to be fully experienced as far as its blood glucose lowering effects go.

For more information about this or any other health-related questions, contact the pharmacists at Gordon Pharmasave, Your Health and Wellness Destination. Also check the website at www.gordon-pharmasave.com/ and the Facebook page at www.facebook.com/GordonPharmasave/?fref=ts