1. NUTRITIONAL PHARMACOLOGY Flashcards
This module covers: • Drug restrictions, administration and metabolism. • Side effects of drugs. • Drug-nutrient interactions. • Drug-induced nutrient depletions. • Major groups and actions of pharmaceutical drugs. • Pharmaceuticals and the nutrition consultation.
Why do nutritional therapists need to know about pharmacology?
- Clients often use a range of complex prescription and over-the-counter drugs.
- Every drug produces side effects e.g., gastric ulceration when taking ibuprofen.
- Food or supplements may interact with a drug producing unwanted effects e.g., increased bleeding risk with warfarin and vitamin E.
- Drugs can lead to important nutrient depletions e.g., metformin and vitamin B12.
Provide a definition for a ‘medicine’ according to the MHRA.
MHRA = Medicines & Healthcare Products Regulatory Agency
“Any substance or combination of substances presented as having properties for treating or preventing disease in human beings.”
OR
“Any substance or combination of substances which may be used in, or administered to, human beings, either with a view to restoring, correcting or modifying physiological functions by exerting a pharmacological, immunological or metabolic action, or to making a medical diagnosis.”
TRUE OR FALSE:
Only prescription drugs need a regulatory licence.
FALSE.
All drugs must have a regulatory licence detailing their intended mode of action.
List four possible supply routes for obtaining medicines
- Prescription only (POM) — supplied only under direction of qualified healthcare professional e.g., doctor’s prescription.
- Controlled medicines — special group of medicines that require extra controls e.g., codeine, morphine.
- Pharmacy only (PO) — sold by a registered pharmacy
- General sales list (GSL) — can be sold via a number of outlets including supermarkets.
What are OTC drugs and which two legally distinct classes are there?
OTC = over the counter
OTC drugs are products that are used to self-medicate a range of common illnesses. They are generally classified by the legal distinction:
- PO (Pharmacy only)
sold and supplied under pharmacist supervision.
- GSL (General sales list)
supplied by a pharmacy and many non-pharmacy outlets e.g., grocery store.
Why might clients choose to self-medicate?
Clients may choose to self-medicate in order:
* To treat a minor ailment e.g., a cough mixture.
* To support a chronic illness when not fully controlled by prescribed medicines e.g., ibuprofen for osteoarthritis.
Which drug class do the following common OTC drugs belong to:
a) Ibuprofen
b) Cetirizine
c) Omeprazole
d) Bisacodyl
a) Analgesic
b) Anti-histamine
c) Proton pump inhibitor
d) Laxative
A drug contains both active and inactive ingredients. What are the difference between these two types of ingredients?
Active ingredient:
This is the part of the drug that is intended to deliver its mode of action and is responsible for side effects e.g., ibuprofen to reduce inflammation.
Inactive ingredients:
These alter the physical properties of the drug e.g., fillers, colouring agents, preservatives, lactose, gluten, aspartame, other E numbers. Studies increasingly show that inactive ingredients can trigger allergic reactions and food intolerances.
In terms of how drugs are described, what is meant by the following:
a) Generic name
b) Brand name
Generic name:
This is the actual active ingredient within the drug e.g., paracetamol (Europe), acetaminophen (US). Paracetamol and acetaminophen are, in fact, the same active ingredient.
Brand name:
Paracetamol can be provided under a number of branded names e.g., Panadol (UK), Tylenol (US).
A nutritional therapist must always look for the generic name.
Explain the following drug terminology:
a) Indication
b) Contraindication
c) Side effects
d) Interactions
a) Indication: What the drug is intended for, e.g., hypertension (high blood pressure).
b) Contraindication: When the drug must not be used e.g., in pregnancy, renal failure.
c) Side effects: Ibuprofen can produce gastric ulcers.
d) Interactions: A drug’s activity is affected by another substance causing an increase, decrease or a new effect.
What is the difference in how drugs and nutrients function in the disease process?
Drugs suppress and manage symptoms (and do not target the actual underlying cause) whilst nutrients encourage the body to restore homeostasis and heal.
Which plant is aspirin derived from and how does it differ from the whole plant?
Aspirin is derived from willow bark (Salix alba) an ancient herb.
- Willow bark contains salicin, which does not convert to salicylic acid (a gastric irritant) until it reaches the bloodstream and body tissues. It naturally reduces fever, inflammation and pain without GI side effects.
- Through research, aspirin was synthetically developed from salicylic acid. Aspirin can cause gastrointestinal bleeding, peptic ulceration and hypersensitivity!
- Willow bark contains numerous active components which influence each other and in totality contribute to its overall healing potential.
Define the following terms:
a) pharmacokinetics
b) pharmacodynamics
a) Pharmacokinetics is the study of the movement of drugs within the body.
b) Pharmacodynamics is the study of how drugs interact with the body to exert their effects.
Which four key processes is involved in pharomacokinetics?
Hint: ADME
The
ABSORPTION,
DISTRIBUTION,
METABOLISM and
EXCRETION
of a drug
Why is it important to keep in mind ‘First Pass Hepatic Metabolism’ in the administration of certain drugs?
First pass metabolism is the process by which drugs taken orally are absorbed from the GIT and taken via the portal vein into the liver to be metabolised. The effects of this mean that drug concentrations can be reduced by the time they enter systemic circulation.
When a drug is extensively metabolised, the amount of drug reaching the bloodstream is greatly reduced and cannot exert its effect. This type of medicine should be administered by a different route e.g., nitro glycerine (GTN) spray for angina.
What are the two main factors that determine whether a drug reaches its target site of action in the body?
-
Bioavailability
This simply refers to the ‘proportion’ of drug that can reach the bloodstream and is, therefore, available for distribution to its intended site of action. -
Route of administration
How a drug is administered e.g., oral tablets, sublingual B12, suppository, injectables, topical creams, patches, all directly influence the medicine’s bioavailability.
Expand on what the following routes of drug administration entails:
a) Oral
b) Sublingual
c) Buccal
d) Topical
e) Parenteral
a) Oral: Tablets, capsules, liquids that are taken by mouth (swallowed). The most frequently used route of administation. Absorption is mainly via the small intestine.
b) Sublingual: Sprays, tablets, films placed under the tongue (e.g. glyceryl trinitrate spray) and directly absorbed into the bloodstream (bypasses liver metabolism).
c) Buccal: Tablets placed between the gum and inner cheek and directly absorbed into the bloodstream (e.g. prochlorperazine maleate tablets).
d) Topical:
‒ Local effect: Creams, patches (Cutaneous route), ear (Otic route) and eye (Ocular route) drops.
‒ Systemic effect: Inhalation (Pulmonary route = rapid effects).
e) Parenteral: Injections: Intravenous, sub-cutaneous, intra-muscular. Avoids the intestines and bypasses liver metabolism.
List three factors, related to the body, that can affect the absorption of a drug.
- Gastro-intestinal motility: Diarrhoea increases motility and reduces absorption.
- Malabsorption states reduce absorption e.g., Coeliac disease.
- Presence of other substances: E.g., absorption of iron is reduced when given with milk.
Which characteristics of a medicine might enhance its absorption?
- Absorption is greatest for lipid soluble and small molecule drugs.
- Acidic drugs absorb quicker in an acidic environment e.g., stomach.
- A liquid medicine will absorb quicker than a solid tablet.
After a drug enters the systemic circulation, it is distributed to the body’s tissues.
List three factors that can affect this distribution.
The distribution of a drug is affected by a number of factors:
- Binding to plasma proteins which affects the active concentration of the drug.
- Binding to other tissues e.g., tetracycline (antibiotic) binds to calcium in bones and teeth.
- Accumulation in lipids e.g., general anaesthetics.
- Natural barriers to distribution e.g., blood brain barrier, placental barrier.
Define: ‘Drug metabolism’
The process by which drugs are chemically changed from a lipid soluble to a more water-soluble form suitable for excretion
Briefly outline what happens during Phase I and Phase II liver detoxification.
- Phase I: Drug / toxin is altered chemically to make it suitable for Phase II reactions or for excretion. Involves the cytochrome P450 enzyme family.
- Phase II: Molecules from Phase I (or in some cases unchanged drugs) are conjugated to a more water-soluble product and aid excretion.
What are the main excretion routes by which drugs and their metabolites are removed from the body?
Urine
Faeces
Which system, if dysfunctional can affect the rate at which a drug / metabolite is cleared from the body?
The renal system
What is ‘entero-hepatic circulation’?
The process by which some drugs (that are very lipid soluble) may be re-absorbed and re-enter the portal vein. This prolongs excretion times.
List three factors that can affect a drug’s mode of action
- Advancing age
- genetic mutations
- malnutrition
- medical conditions e.g., Parkinson’s disease, Alzheimer’s disease.
What are ‘side effects’?
Side effects are unpleasant, unwanted effects of a drug.
They range from mild to severe and in some cases life-threatening and are categorised by occurrence e.g.,
very common, common, uncommon or rare.
Why is it important to be aware of the potential side effects of the drugs a client is taking?
It is important to consider that a client’s presenting signs and/or symptoms could be due to a drug’s side effects.
What long-term side effects are patients at risk for when using the following medications:
a) Metformin
b) Thiazide diuretics
c) Corticosteroids
d) Opiate analgesics
a) Metformin: Vit B12 deficiency
b) Thiazide diuretics: Gout
c) Corticosteroids: Osteoporosis
d) Opiate analgesics: Dependence
List FOUR worrying and serious side effects from the long-term use of PPIs.
- Bone fractures.
- Hypomagnesaemia (low blood magnesium).
- Vitamin B12 deficiency.
- Bacterial enteric infections e.g., serious Clostridium difficile.
- Rebound acid hypersecretion (when PPI is stopped).
- Kidney disease.
- Dementia.
What is the concerning risk with the use of diclofenac (an NSAID)?
It was widely accepted that diclofenac (NSAID) increased the risk of cardiovascular events yet the product was commonly prescribed by medical doctors.
As a nutritional therapist, what should you do if you suspect that a client is experiencing side effects
- Check the presenting sign / symptom against the drug in your selected resource e.g., the BNF.
- Advise the client to consult his / her GP or medical specialist.
- Ensure that the food or supplement that you recommend does not interact with the client’s drug which could then cause side effects.
Explain how the cytochrome P450 system affects drugs
The cytochrome P450 enzyme family alters drugs / toxins chemically to make it suitable for Phase II liver detoxification.
An interaction occurs when the effects of one drug are altered by the co-administration of another substance.
List three types of substances that can lead to interactions.
- Drugs.
- Herbal medicines.
- Food and drinks.
- Nutritional supplements.
- Environmental chemical agents.
What are Narrow Therapeutic Index (NTI) drugs. Give two examples.
Drugs that may become dangerously toxic or ineffective with only relatively small changes in their blood concentrations.
Examples: Digoxin, phenytoin, theophylline, warfarin, lithium.
During a consultation it is essential that these medicines are clearly highlighted on case notes.
