Drugs Part 2

How does a doctor select a drug for treatment?

The best use of pharmacology is medicine tailored toward treating the diagnosis. The doctor should know how to make a diagnosis. Some diagnoses are clinical — a careful history and examination clinches the diagnosis, and other diagnoses require laboratory or radiologic investigations.

Many conditions respond to one of several drugs within a class. Drugs are often categorized by groups of similar molecules. Naming conventions can be helpful. Beta blockers, for example, commonly have names that end in -olol. Propranolol, metoprolol, atenolol, etc.

Each drug in a class has a similar mechanism of action but unique physical properties related to kinetics and pharmacodynamics. Each drug has its own FDA approvals and costs.

Drug selection choice might occur in the following fashion (broad to narrow):

1. First line group identified

2. Most efficacious drug recommended first

3. Most tolerated drug recommended second

4. Least expensive drug recommended third

5. Second line group identified

   …

And so on

This process might occur without discussion between the patient and the doctor. There might be dozens of medicines that could possibly treat a specific condition. It is safe to assume the doctor will recommend the one with the best evidence for use.

Newer does not always mean better! Newer does always means more expensive. Pharmaceutical representatives are paid to inform clinicians of the unique properties of the drug they represent. Surgical device representatives seem to have a larger influence than pharmaceutical representatives, but overall representatives are able to create a bias in a fraction of doctors.

What medicine combinations are dangerous?

Most medications are safe to take together. However, some combinations can be dangerous like two waves stacking on top of one another to form a super wave. History is on our side: drugs fall out of use pretty quickly if one of the side effects is death.

Medicines that interfere with clotting (“blood thinners”), when taken together, can make a fall deadly from the internal bleeding.

Medicines that suppress respiratory drive, when combined, can make sleep deadly. E.g., opioids and sleepers together.

Medicines that lower the seizure threshold, when added together, can make seizures much more likely.

Deadly drug combinations can cause a cascade of biochemicals to build up and overwhelm a vital organ.

Some deadly combinations occur from two drugs opposing effect with each other.

Medicines that block feelings of fatigue and increase sedation make driving deadly. E.g., psychostimulant and benzodiazepine.

Prescribing software automatically flags dangerous combinations. Likewise, pharmacy software flags dangerous combinations.

A drug-interaction search of your medicine cocktail is appropriate every time a new drug is added.

A common misconception about drug combinations: The act of taking the drugs simultaneously, such as within a few seconds of each other, is not usually the dangerous part. In reality, concurrent use is relevant to risk. Imagine someone consuming 3 drinks in an hour and another person consuming 3 drinks all at once — their blood alcohol levels will be similar after an hour.

Speaking of alcohol…

Is alcohol safe to drink with medicine?

Alcohol is not recommended. However, if one chooses to imbibe responsibly, should medicine be paused at all? For the day? The night? The week?

Medicine that acts on the central nervous system (CNS) will likely have a warning not to drink alcohol with the medicine.

Some of the milder risks are feeling more intoxicated with lower amounts of alcohol and increased sedation.

However, certain CNS medicines act on the same receptors as alcohol — these are benzodiazepines (commonly used for anxiety), Z-drugs (sleepers such as zolpidem), and barbiturates (uncommon except for butalbital).

CNS stimulants, such as Adderall, Ritalin, cocaine, and methamphetamine, are dangerous with alcohol because the alertness from the stimulant may mask the sedated feeling of intoxication and lead to over drinking.

Knowing which medicines require a daily dose to gain effect and which medicines can be started and stopped in a day is vital. Having ONE drink ONCE with a daily CNS medication such as an antidepressant, anti-epileptic, antipsychotic, is unlikely to cause significant impairment. Otherwise, do not drink within 24 hours of taking a CNS agent.

Reiteration: no amount of alcohol is recommended, but alcohol is a reality of humanity that prescribers must acknowledge.

I forgot a dose, now what?

When in doubt, a missed dose can be a missed dose. For many medicines it is okay to make up the missed dose as soon as it is noticed, just check with a pharmacist or doctor first.

Medicine frequency is often about efficacy rather than safety. The fact is, if we miss too many doses then the blood level of the drug will fall below the effective range.

A pill organizer increases adherence to daily medicines.

I am better now, can I stop the medicine?

It depends. Chronic conditions may require indefinite use to maintain improvement. For example, medicine that lowers blood pressure does not cure high blood pressure, and so discontinuing the medicine reveals the signs of the chronic condition.

Often feeling better makes us eager to prove we are all better. A common pitfall patients discover is discontinuation of treatments leads to return of symptoms. The nation is discovering this about GLP-1 drugs for weight loss. Discontinuation of an appetite suppressant will correlate with a gradual gain of abdominal mass unless the person has discovered how to be hungry and not eat delicious food (extreme high level of difficulty).

The most effective preventative chemicals are vaccines. These chemicals stimulate the bodies immune system to be prepared for exposure to pathogens and resist disease. Some vaccines require boosters or a series, but otherwise vaccines are the thing everyone wishes modern medicine could be — one-off preventers of deadly illnesses, eradicators of disease, and protection for our most vulnerable loved ones even if they themselves are not able to receive a vaccine.

Treatments that are “as needed” (PRN or pro re nata in medical lingo) are stopped as soon as improvement occurs. Treatments that are a series or course are often continued until the course is complete.

Patients who ask permission to discontinue medicine might be able to engage in an open discussion about pros and cons of treatment. Patients who spontaneously discontinue medicine might discover no problem, but might also find discomfort or a dangerous return of underlying symptoms. Curiosity is better satiated under doctor supervision.

How can I be sure the medicine I take is not going to kill me?

Something is going to kill you someday, but almost definitely not your daily medicine taken properly for a common chronic condition. In the olden days, psychiatrists had to warn patients not to eat grapefruit when taking certain medicines. Once safer medicines came along we used the safe medications and stopped warning people about food in their kitchen.

Drugs are designed to be safe. Reiteration: deadly drugs do not fare well in the market that has tens of thousands of options.

It is a common worry that a long term medicine does more harm than good. This is an area of post-market research investigation. There are medicines that can harm the liver or the kidneys over time, so those organ systems need to be monitored periodically. Rare allergy and hypersensitivity drug reactions can occur when initiating a new medicine, and the drugs most commonly associated with rare risks have warnings indicating such. Common use drugs must do more good than harm lest they be banned from consumer access.

Drug anxiety is common in those with anxiety disorders. Drug anxiety increases the perception of side effects to medicines. For some, the feeling that they have harmed themselves by taking a medicine is very powerful. Low and intermittent dosing to establish tolerance is a common approach to overcoming the negative feeling and the side effects.

Are drugs cool to take?

I would not know. Doctors are notoriously nerdy. Self-prescribing is frowned upon and I do not like seeing authorities frown upon me. But I do have a doctor I talk to and I do take medicine that it is recommended to me. I am not afraid of any of the medicines I commonly prescribe to others and would be willing to take my own medicine if recommended to do so by my doctor.