Drug synergism arises when the therapeutic effect of two or more drugs used in combination is greater than the sum of the effects of the drugs administered individually.

Drug interactions occur when one drug alters the pharmacological effect of another drug. The pharmacological effect of one or both drugs may be increased or decreased, or a new and unanticipated adverse effect may be produced.

Pharmacodynamic interactions are those in which drugs influence each other’s effects directly. Often, however, a pharmacodynamic interaction is actually desired, if mutually potentiating effects in the same direction (synergistic effects) are aimed at, e.g., in the use of anti-infectives or in pain therapy.

Synergism, Synergy. An interaction between two or more drugs that causes the total effect of the drugs to be greater than the sum of the individual effects of each drug.

Drug interactions can be categorised into 3 groups:

• Interactions of drugs with other drugs (drug-drug interactions),
• Drugs with food (drug-food interactions)
• Drug with disease condition (drug-disease interactions).

Two or more drugs that individually produce overtly similar effects will sometimes display greatly enhanced effects when given in combination. When the combined effect is greater than that predicted by their individual potencies, the combination is said to be synergistic.

pharmacokinetic – defined as an alteration in the absorption, distribution, metabolism or excretion of one drug by another. This is the most common type of drug interaction. pharmacodynamic – where the drug affects the action or effect of the other drug.

Definition: A biologic response to exposure to multiple substances that is less than would be expected if the known effects of the individual substances were added together.

5 Over-the-Counter Medicines You Should Never Take Together

• Dangerous duo: Tylenol and multi-symptom cold medicines.
• Dangerous duo: Any combo of ibuprofen, naproxen, and aspirin.
• Dangerous duo: Antihistamines and motion-sickness medications.
• Dangerous duo: Anti-diarrheal medicine and calcium supplements.
• Dangerous duo: St.

3 Common Medicines You Should Never Mix

• Warfarin and Ibuprofen. Separately, warfarin and ibuprofen are two commonly used drugs. Warfarin (brand name: Coumadin) is a popular anticoagulant.
• Multi-Symptom Cold Medicine and Tylenol. It’s a miserable day.
• Antidepressants and Painkillers. Depression is widespread in the United States, affecting 40 million adults.

Taking your medications at the proper intervals during the day. Try to divide up your dosing times as evenly as possible throughout the day: for example, every 12 hours for a drug that needs to be taken twice a day, or every 8 hours for a drug that needs to be taken three times a day.

QID: Four times a day. QHS: Before bed. Q4H: Every 4 hours. Q6H: Every 6 hours.

It’s usually safe to take medicine 1-2 hours early or late, but don’t double up doses.

Do I need to take each dose exactly twelve hours apart? None of the asthma medications prescribed by your physician needs to be taken exactly twelve hours apart. Twice-a-day usually means morning and evening, on arising and on going to bed, or even at breakfast and supper.

It is usually taken every 12 hours (twice a day) or every 8 hours (three times a day) with or without food. The length of your treatment depends on the type of infection that you have.

b.i.d. (or bid or BID) is two times a day ; b.i.d. stands for “bis in die” (in Latin, twice a day).

If you’re giving the wrong medication, it could result in anything from a slight annoyance, to your death. If you feel like you or someone in your family was given the wrong medication, contact your pharmacy and your doctor immediately. Follow the instructions they give you carefully. Always err on the side of caution.

Maintenance medications – meds you take daily to manage a condition or treat a chronic problem – are most effective when you: Take them around the same time every day, which also helps you remember to take them.

“Take every 8 hours” generally means the medicine should be taken 3 times a day.

Be careful not to become overheated or dehydrated in hot weather while taking hydrochlorothiazide. Talk to your doctor about how much fluid you should be drinking; in some cases drinking too much fluid is just as harmful as not drinking enough fluids.

Taking daily doses of two blood pressure drugs (fixed dose candesartan and hydrochlorothiazide) along with a cholesterol-lowering drug (low-dose rosuvastatin), proved to be the most effective, cutting first-time strokes by 44 percent among patients at intermediate risk for heart disease.

To maximize the effects of statins with a short half-life, fluvastatin, lovastatin, and simvastatin should be dosed at bedtime allowing the greatest drug concentration to be present during peak endogenous cholesterol synthesis.

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You usually have to continue taking statins for life because if you stop taking them, your cholesterol will return to a high level within a few weeks. If you forget to take your dose, do not take an extra one to make up for it. Just take your next dose as usual the following day.