Using Drugs

If you want to be a carpenter, you’d better learn how to use a hammer and saw. If you’re going to be a doctor, pharmacist, nurse, naturopath or other health care provider, you’d better learn how to prescribe, dispense or administer a drug. Without adequate training the chance of causing serious problems is great.

There are several different kinds of drugs that can be useful in chronic pain. Within each kind or class of drug are individual drugs that share certain characteristics. Each has its own special characteristics that must be understood if the drug is to be used safely and properly. Fortunately there are several basic principles that can guide us to work with drugs effectively.

Generally speaking, drugs have a therapeutic window. In other words, drugs will have no effect below a certain dose and can cause harmful effects above a certain dose. Too often I see patients take inadequate doses of a drug because they are afraid a drug is too strong. Just as frequently, patients may exceed safe doses in their desperation for pain relief even though no more pain relief is forthcoming beyond a certain dose. I usually advise people not to think in terms of strength or weakness of a drug but instead consider the therapeutic window for any drug they take.

In order to be effective, many drugs used in chronic pain need to be used continuously and may have little or no benefit if taken intermittently. Examples include antidepressants (e.g. amitriptyline and duloxetine) and anticonvulsants (e.g. gabapentin and pregabalin). Testing (see TESTING) has shown that having a particular level always present in the body is what produces benefits. When levels fall from too many missed doses, the benefits disappear but not necessarily the risk of adverse effects. Yet some patients will use these dugs only intermittently in the same way they would use short acting painkillers and then wonder why they get little benefit. Such drugs need to be taken on a regular schedule if they are going to work well.

Individuals respond differently to the same drug. The process of determining the best dose for someone is called titrating the dose to effect. This involves starting treatment with a very low dose and gradually increasing it at specified intervals until the desired effect is achieved. Sometimes adverse effects can be minimized by using this method and other times the drug will have to be abandoned when adverse effects become intolerable. One of the more frequent errors I see is stopping a drug for lack of success when it has not been properly titrated. The reason is often related to worry about taking high doses. Knowledge of the drug’s therapeutic window should be used to guide titration rather than a preconceived notion of what constitutes a high dose.

Many drugs cause habituation. This means they can cause withdrawal symptoms if stopped abruptly. Habituation should not be confused with addiction. Antidepressants, tranquilizers, some anticonvulsants, some heart drugs and others can cause withdrawal problems as serious as those of narcotics. Weaning is the process of gradually reducing a dose to discontinue it. This usually minimizes withdrawal symptoms. In some cases other drugs must be administered to reduce withdrawal. Sometimes, hospitalization may be required but fortunately, this is not common.

Tolerance is the term used to describe what happens when a drug loses its effect over time. This occurs frequently with opioid use and represents a significant problem for some patients. While higher doses may provide the same effect, it is not possible to keep raising doses indefinitely. Sometimes one drug can be switched for a similar drug at an equivalent dose and rotating drugs may work for some people. Temporarily stopping a drug may also help. Opioids can sometimes cause pain (the term for this is opioid induced hyperalgesia) and this may be confused with tolerance. Reducing or stopping the drug is the only way to manage this problem. Of course, other methods/drugs for pain control will likely be needed.

Finally, if a drug is not producing tangible benefits in a reasonable amount of time, it should be stopped. I am often astonished by the number of patients I see taking anti-inflammatory drugs sometimes for months and years with no benefit. Anti-inflammatory drugs should reach maximum effect after 10 to 14 days. Other drugs such as antidepressants may take several weeks or longer to titrate.  Once the maximum dose has been reached and there has been little relief, there is no point in continuing.

When you seek information about a drug, be sure to look beyond the long lists of frightening adverse effects and drug interactions to find out about the therapeutic window, dose titration and dose scheduling. When you must take a drug, take it properly.

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