DRUG INTERACTION

&
DRUG RESISTANCE

DR. ARCHANA
 DRUG INTERACTION
• A drug interaction is a reaction between two (or more) drugs (called a
drug-drug interaction) or between a drug and a food or beverage (called
a drug-food interaction).

• An existing medical condition can make certain drugs potentially harmful

(called a drug-condition interaction).

• For example, taking a nasal decongestant if you have high blood

pressure may cause an unwanted reaction.

• Medicines help us feel better and stay healthy. But drug interactions can
cause problems by reducing or increasing the action of a medicine or
causing adverse effects.
Drug interactions fall into three broad categories:
• Drug-drug interactions occur when two or more drugs react with each other. This
drug-drug interaction may cause you to experience an unexpected side effect. For
example, mixing a drug you take to help you sleep (a sedative) and a drug you take for
allergies (an antihistamine) can slow your reactions and make driving a car or operating
machinery dangerous.

• Drug-food/beverage interactions result from drugs reacting with foods or beverages. For
example, mixing alcohol with some drugs may cause you to feel tired or slow your
reactions.

• Drug-condition interactions may occur when an existing medical condition makes certain
drugs potentially harmful. For example, if you have high blood pressure you could
experience an unwanted reaction if you take a nasal decongestant.
 EXAMPLES OF DRUG INTERACTIONS
Category Drug Interaction Information

Acid Reducers taking theophylline (oral asthma drug), warfarin (blood

H2 Receptor Antagonists thinning drug), or phenytoin (seizure drug)
(drugs that prevent or relieve heartburn
associated with acid indigestion and sour
stomach)
Antacids allergic to milk or milk products if the product contains
(drugs for relief of acid indigestion, heartburn, more than 5 grams lactose in a maximum daily dose
and/or sour stomach) taking a prescription drug
kidney disease

Antiemetics taking sedatives or tranquilizers

(drugs for prevention or treatment of nausea, a breathing problem, such as emphysema or chronic
vomiting, or dizziness associated with motion bronchitis
sickness) glaucoma
difficulty in urination due to an enlarged prostate gland
When using this product: avoid alcoholic beverages
 EXAMPLES OF DRUG INTERACTIONS
Category Drug Interaction Information

Antihistamines sedatives or tranquilizers

(drugs that temporarily relieve runny nose or reduce a prescription drug for high blood pressure or
sneezing, itching of the nose or throat, and itchy depression
watery eyes due to hay fever or other upper glaucoma or difficulty in urination due to an enlarged
respiratory problems) prostate gland
breathing problems, such as emphysema, chronic
bronchitis, or asthma
When using this product: Avoid alcohol, sedatives,
and tranquilizers - may increase drowsiness
Antitussives taking sedatives or tranquilizers
Cough Medicine glaucoma or difficulty in urination due to an enlarged
(drugs that temporarily reduce cough due to minor prostate gland
throat and bronchial irritation due to cold)
Laxatives kidney disease and the laxative contains
(drugs for the temporary relief of constipation) phosphates, potassium, or magnesium
stomach pain, nausea, or vomiting
 EXAMPLES OF DRUG INTERACTION
Category Drug Interaction Information

Nasal Decongestants have heart disease, high blood pressure, thyroid

(drugs for the temporary relief of nasal congestion disease, diabetes, or difficulty in urination due to
due to a cold, hay fever, or other upper respiratory an enlarged prostate gland
allergies)
Pain Relievers consume three or more alcohol-containing drinks
(drugs for the temporary relief of minor body per day
aches, pains, and headaches)
Topical Acne increased dryness or irritation of the skin may
(drugs for the treatment of acne) occur immediately following use of this product or
if you are using other topical acne drugs at the
same time. If this occurs, only one drug should be
used unless directed by your doctor
 DRUG – FOOD INTERACTION
Food Mechanism Drugs affected

Avocado Enzymatic inductor Acenocoumarol, warfarin

Brassicas (brussel
sprouts, broccoli,
cabbage)
Grapefruit juice Enzymatic Calcium channel
inhibition blockers: nifedipine, felodipine, nimodipine, a
mlodipine
Cyclosporine, tacrolimus
Terfenadine, astemizole
Cisapride, pimozide,Carbamazepine, saquin
avir, midazolam, alprazolam, triazolam
Soya Enzymatic Clozapine, haloperidol, olanzapine, NSAIDs,
inhibition phenytoin, zafirlukast, warfarin
 DRUG – FOOD INTERACTION

Food Mechanism Drugs affected

Ginseng Unknown Warfarin, heparin, aspirin
and NSAIDs

Ginger Inhibits thromboxane Anticoagulants

synthetase
Chamomile Unknown Benzodiazepines, barbitur
ates and opioids

Garlic Increases antiplatelet Anticoagulants

activity NSAIDs, acetylsalicylic acid
Drug Interaction depends upon factors such as:
• Total number of medications you take
• Age, kidney and liver function
• Diet and possible drug interactions
• Medical conditions
• Metabolic enzymes in body and genetics
How do drug interactions occur?
• There are several mechanisms by which drugs interact with
other drugs, food, and other substances.
• An interaction can result when there is an increase or
decrease in:
• the absorption of a drug into the body;
• distribution of the drug within the body;
• alterations made to the drug by the body (metabolism);
and
• elimination of the drug from the body.
Most of the important drug interactions result from a change in the absorption,
metabolism, or elimination of a drug.

1. Drug interactions also may occur when two drugs that have similar (additive)
effects or opposite (canceling) effects on the body are administered together. For
example, there may be major sedation when two drugs that have sedation as side
effects are given, for example, narcotics and antihistamines.

2. Another source of drug interactions occurs when one drug alters the concentration
of a substance that is normally present in the body. The alteration of this
substance reduces or enhances the effect of another drug that is being taken. The
drug interaction between warfarin (Coumadin) and vitamin K-containing products
is a good example of this type of interaction. Warfarin acts by reducing the
concentration of the active form of vitamin K in the body. Therefore, when vitamin
K is taken, it reduces the effect of warfarin.
How can drug interactions be avoided?
• Give health care practitioners a complete list of all of the drugs that you are using
or have used within the last few weeks. This should include over-the-counter
medications, vitamins, food supplements, and herbal remedies.

• Inform health care practitioners when medications are added or discontinued.

• Inform health care practitioners about changes in lifestyle (for example, exercise,
diet, alcohol intake).

• Ask your health care practitioners about the most serious or frequent drug
interactions with the medications that you are taking.

• Since the frequency of drug interactions increases with the number of medications,
work with your health care practitioners to eliminate unnecessary medications.
Why it's important to check for interactions
Drug interactions are important to check for because they can:

• Affect how your medication works by changing levels of the drug in

your blood

• Put you at risk for side effects and toxicity

• Worsen a medical condition you may already have.
DRUG INTERACTION CHECKERS

WebMD

• https://www.webmd.com/interaction-checker/default.htm
Medscape

• https://reference.medscape.com/drug-interactionchecker
Drugs.com

• https://www.drugs.com/drug_interactions.html
DRUG RESISTANCE
 BRIEF HISTORY OF ANTIBIOTICS
• Humans developed antimicrobials to destroy disease-causing
microbes. The most commonly known antimicrobials are antibiotics,
which target bacteria. Other forms of antimicrobials are antivirals,
antifungals, and anti-parasitics.

• Penicillin, the first commercialized antibiotic, was discovered in 1928

by Alexander Fleming. While it wasn’t distributed among the general
public until 1945, it was widely used in World War II for surgical and
wound infections among the Allied Forces. It was hailed as a “miracle
drug” and a future free of infectious diseases was considered. When
Fleming won the Nobel Prize for his discovery, he warned of bacteria
becoming resistant to penicillin in his acceptance speech.
 ANTIMICROBIAL / ANTIBIOTIC RESISTANCE
• Antimicrobial resistance is the ability of microbes, such as bacteria, viruses, parasites, or
fungi, to grow in the presence of a chemical (drug) that would normally kill it or limit its
growth.

• Non-resistant bacteria multiply, and upon drug treatment, the bacteria die. Drug resistant
bacteria multiply as well, but upon drug treatment, the bacteria continue to spread.

• It is important to make a distinction between antibiotic resistance and antimicrobial

resistance. While antibiotic resistance refers specifically to the ability of bacteria to resist
antibiotics, antimicrobial resistance is a more general term that covers resistance from any
microbes to the drugs used to kill them.

• When the microorganisms become resistant to most antimicrobials they are often referred
to as “superbugs”.

• Antibiotic resistance leads to higher medical costs, prolonged hospital stays, and
increased mortality.
 IMPACT / CONSEQUENCES
• Physicians have to recommend second- or third-choice drugs for treatment when the
bacteria that cause infections are resistant to the drug of choice and this drug doesn’t
work. But the alternative drugs might be less effective, more toxic, and more
expensive. Preserving the effectiveness of antibiotics is vital to protecting human and
animal health.

• When infections can no longer be treated by first-line antibiotics, more expensive

medicines must be used. A longer duration of illness and treatment, often in hospitals,
increases health care costs as well as the economic burden on families and societies.

• Antibiotic resistance is putting the achievements of modern medicine at risk. Organ

transplantations, chemotherapy and surgeries such as caesarean sections become
much more dangerous without effective antibiotics for the prevention and treatment of
infections.
• Prevention and control - Antibiotic resistance is accelerated by the misuse and overuse of
antibiotics, as well as poor infection prevention and control. Steps can be taken at all levels of
society to reduce the impact and limit the spread of resistance.

• Individuals
• Only use antibiotics when prescribed by a certified health professional.
• Never demand antibiotics if your health worker says you don’t need them.
• Always follow your Doctor’s advice when using antibiotics.
• Never share or use leftover antibiotics.
• Prevent infections by regularly washing hands, preparing food hygienically, avoiding close
contact with sick people, and keeping vaccinations up to date.

• Prepare food hygienically, following the WHO Five Keys to Safer Food (keep clean, separate
raw and cooked, cook thoroughly, keep food at safe temperatures, use safe water and raw
materials) and choose foods that have been produced without the use of antibiotics for
• Health professionals
• Prevent infections by ensuring your hands, instruments, and environment
are clean.

• Only prescribe and dispense antibiotics when they are needed, according to
current guidelines.

• Report antibiotic-resistant infections to surveillance teams.

• Talk to your patients about how to take antibiotics correctly, antibiotic
resistance and the dangers of misuse.

• Talk to your patients about preventing infections (for example, vaccination,

hand washing, and covering nose and mouth when sneezing).
Does stopping a course of antibiotics early lead to antibiotic
resistance?
• If you are being treated for an infection, the kind of antibiotics your doctor prescribes and
the length of the course should be based on the best evidence.

• Feeling better, or an improvement in symptoms, does not always mean that the infection
has completely gone. Your doctor has had years of training and has access to the latest
evidence – so always follow their advice.

• Evidence is emerging that shorter courses of antibiotics may be just as effective as longer
courses for some infections. Shorter treatments make more sense – they are more likely to
be completed properly, have fewer side effects and also likely to be cheaper. They also
reduce the exposure of bacteria to antibiotics, thereby reducing the speed by which the
pathogen develops resistance.

• WHO publishes guidelines about treatments for different infections and recommends
treatment durations and doses of antibiotics based on the best clinical evidence for each
case.
Thank You!