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Nutrition 2 - Semester ! > Pharmacology > Flashcards

Pharmacology Flashcards

1
Q

A medicine is

A

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

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2
Q

How drugs are supplied

A
  • Prescription only (POM)
    ‒ Controlled medicines
    ‒ Pharmacy only (PO)
    ‒ General sales list (GSL)
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3
Q

Prescription only (POM)

A

supplied only under direction of qualified healthcare professional e.g., doctor’s prescription

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4
Q

Controlled medicines

A

special group of medicines that require extra controls e.g., codeine, morphine

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5
Q

Pharmacy only (PO)

A

sold by a registered pharmacy

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6
Q

General sales list (GSL)

A

can be sold via a number of outlets including supermarkets

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7
Q

OTC drugs

A

OTC drugs are products that are used to self-medicate a range of common illnesses:

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8
Q

OTC drugs are generally classified by the legal distinction

A

‒ PO — sold and supplied under pharmacist supervision.

‒ GSL — general sales list supplied by a pharmacy and many non-pharmacy outlets e.g., grocery store.

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9
Q

Common OTC drugs

A
  • Analgesics (codeine, paracetamol, aspirin, ibuprofen).
  • Laxatives (bisacodyl, senna).
  • Proton pump inhibitors (omeprazole).
  • Cough mixtures (diphenhydramine).
  • Anti-histamines (chlorphenamine, cetirizine).
  • Decongestants (pseudoephedrine).
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10
Q

A drug contains…

A
  • 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
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11
Q

Drug vs Nutrient?

A

Drugs suppress and manage symptoms, do not target the actual underlying cause!

Nutrients encourage the body to restore homeostasis and heal.

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12
Q

Pharmacokinetics

A

Pharmacokinetics is the study of the movement of drugs within the body

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13
Q

Pharmacodynamics

A

How drugs interact with the body to exert their effect

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14
Q

Key processes of pharmacokinetics

A

Absorption,
distribution,
metabolism
elimination (ADME)

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15
Q

Absorption

A

To exert its action (or toxicity) internally, a drug must first enter the body and be absorbed into the bloodstream.

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16
Q

Distribution

A

In the bloodstream, the drug can now be distributed to its target site (normally a receptor) to exert its action.

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17
Q

Metabolism

A

Once the drug and receptor have interacted, the drug returns to the bloodstream and progresses to the liver to be metabolised and then eliminated from the body.

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18
Q

Excretion

A

Once metabolised, excretion normally takes place via urine or bile

  • Main excretion routes: Urine, faeces.
  • Minor excretion routes: Exhaled air, sweat, saliva, tears.
  • Renal excretion is the normal route for elimination of small water-soluble molecules. Renal dysfunction can, therefore, affect the rate at which a drug / metabolite is cleared from the body.
  • Some drugs (very lipid soluble) may be re-absorbed and re-enter the portal vein. This is known as ‘entero-hepatic circulation’ and prolongs excretion times
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19
Q

First pass metabolism

A

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
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20
Q

Bioavailability

A

‘proportion’ of drug that can reach the bloodstream and is, therefore, available for distribution to its intended site of action.

21
Q

Route of administration

A

how a drug is administered e.g., oral tablets, sublingual B12, suppository, injectables, topical creams, patches, all directly influence the medicine’s bioavailability

22
Q

Drugs administration

A
  • Oral: Tablets, capsules, liquids:
    ‒ Absorption is mainly via the small intestine.
  • Sublingual / buccal:
    ‒ Sublingual / buccal: e.g., glyceryl trinitrate spray. ‒ Bypasses liver metabolism.
  • Topical:
    ‒ Local effect: Creams, patches, ear and eye drops. ‒ Systemic effect: Inhalation (rapid effects).
  • Parenteral:
    ‒ Injections: Intravenous, sub-cutaneous, intra-muscular.
23
Q

Factors Affecting Absorption

A

Related to the body:
* 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.

Related to the medicine:
* 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.

24
Q

Factors Affecting Distribution

A

– 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.

25
Q

Drug metabolism

A

the process by which drugs are chemically changed from a lipid soluble to a more water-soluble form suitable for excretion:

  • 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.
26
Q

What Affects Pharmacodynamics?

A
  • Factors affecting a drug’s mode of action include advancing age, genetic mutations, malnutrition, medical conditions e.g., Parkinson’s disease, Alzheimer’s disease.
  • Together pharmacokinetics and pharmacodynamics provide information about a drug’s:

‒ Mode of action and administration route.

‒ Dosage (incl. knowledge of toxic doses).

‒ Side effects and drug interactions.

27
Q

Side effects

A

Side effects are unpleasant, unwanted effects of a drug.

  • They range from mild to severe and in some cases life-threatening.
  • Categorised by occurrence e.g., very common, common, uncommon or rare.
  • Nausea and vomiting.
  • Headache.
  • Dizziness.
  • Constipation.
  • Diarrhoea.
  • Indigestion.
  • Skin rashes.
  • Dry mouth.
  • Insomnia.
27
Q

long-term side effects

A

The longer a drug is prescribed, the higher the risk of long-term side effects. These include:

  • Nutrient deficiencies e.g., metformin and B12 deficiency.
  • Metabolic effects e.g., omeprazole and hypomagnesaemia.
  • Dependence e.g., diazepam, opiate analgesics (codeine).
  • Osteoporosis e.g., corticosteroids.
  • Gout e.g., thiazide diuretics.
  • Cardiovascular disease e.g., diclofenac (NSAID).
  • Peptic ulceration e.g., NSAID
28
Q

Proton Pump Inhibitor (PPI)

A

PPIs are associated with a number of long-term worrying and serious side effects:

  • 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.
29
Q

Drug Interactions

A

An interaction occurs when the effects of one drug are altered by the co-administration of another substance. Other substances can include:

  • Drugs.
  • Herbal medicines.
  • Food and drinks.
  • Nutritional supplements.

The risk of drug interactions increases with the number of drugs used (polypharmacy) and this can place certain patient populations at increased risk of serious side effects:

  • Patients experiencing renal and liver dysfunction (metabolism and excretion of drugs!).
  • Elderly patients who take more medicines and whose renal and liver function is declining.
  • Patients taking drugs for chronic long-term illnesses e.g., same patient has epilepsy, diabetes and cardiovascular disease (think of the number of drugs administered!)
30
Q

Narrow Therapeutic Index (NTI) drugs

A

Drugs that may become dangerously toxic or ineffective with only relatively small changes in their blood concentrations.

Examples: Digoxin, phenytoin, theophylline, warfarin, lithium

31
Q

Drug — Nutrient Interactions: GARLIC

A

Garlic:

  • Interactions have been reported with cholesterol and blood pressure drugs, such as atorvastatin, propranolol, hydrochlorothiazide or captopril.
  • Garlic could theoretically interact with anticoagulant or antiplatelet drugs, but current evidence has shown that at 4g / day it has little effect on warfarin-stabilised patients.
  • Garlic interspersed throughout the diet is okay, but regular, high dietary intake and / or supplements could allow for interactions.
32
Q

Drug — Nutrient Interactions: GINKGO

A

Ginkgo:

  • Should be avoided with any antiplatelet and anti-coagulant medication, as it has a small potential to increase bleeding risk. It should be stopped one week before surgery.
  • Due to possible CYP induction, it is best to monitor with the following drugs: Benzodiazepines (sedatives), anti-epileptic medication, antipsychotic drugs, diabetic drugs, HIV medications, omeprazole (for gastrointestinal reflux), nifedipine and talinolol (blood pressure drugs).
33
Q

Drug — Nutrient Interactions: GRAPEFRUIT and POMEGRANATE

A

Grapefruit:

  • Selectively inhibits CYP3A4 in the intestinal wall for up to 24 hours, but NOT in the liver. Caution is advised with the many drugs that are metabolised via this pathway ― e.g., digoxin, statins. CYP 3A4 is involved in the metabolism of over 50% of all drugs.

Pomegranate:
* Similar interactions to grapefruit

34
Q

Drug — Nutrient Interactions: GREEN VEGS

A

Green vegetables:

  • Large amounts of green vegetables such as broccoli, spinach, cabbage, Brussels sprouts, seem to reduce the effect of anticoagulants such as warfarin.
  • They contain indoles which increase the metabolism of warfarin, and also contain vitamin K, which reduces the anti-clotting effects of warfarin. Vitamin K is a coagulant, whilst warfarin is an anti-coagulant.
35
Q

Drug — Nutrient Interactions: SOY

A

Soy:

  • Soy decreases absorption of levothyroxine:

Separate ingestion by three hours.

  • Soy may also interfere with oestrogen-blocking drugs such as Tamoxifen, due to its isoflavone (phytoestrogen) content (both positive and negative effects observed).
  • Soy may reduce the effectiveness of warfarin
36
Q

Drug — Nutrient Interactions: DAIRY, Ca

A

Dairy produce / calcium:

  • Calcium can bind to antibiotics like the quinolones and tetracycline, and also bisphosphonates reducing their absorption; reduces levothyroxine absorption (take four hours apart).
37
Q

Diets effect on medication

A
  • High protein diets may reduce the effects of theophylline (appears to increase renal clearance) and L-Dopa (decreases intestinal absorption and interferes with transport from the bloodstream to the brain).
  • High-fibre diets can reduce serum levels of tricyclic antidepressants e.g., amitriptyline (decreases intestinal absorption ― take medication away from high-fibre meals).
  • Salt restriction can increase serum lithium to toxic levels (sodium is involved in active transport of lithium, low levels can cause lithium to accumulate in cells)
38
Q

PPI: Nutrient depletion

A

Reduced gastric acid levels inhibit absorption: Beta-carotene, calcium chromium, iron, magnesium, folate, vit. B12, vit. C, zinc.

39
Q

Steroids: Nutrient depletion

A

Increase urinary excretion, losses from bone tissue: Calcium, vit. D, chromium, folic acid, magnesium, potassium, strontium, zinc.

40
Q

Statins: Nutrient depletion

A

Block synthesis of mevalonic acid, which is a precursor of cholesterol and coenzyme Q10

41
Q

Antibiotics: Nutrient depletion

A

Destruction of normal intestinal microflora may lead to decreased production of various B vitamins and vitamin K: Biotin, pantothenic acid (B5), pyridoxine (B6) riboflavin (B2), thiamine (B1), vit. B12, vit. K

42
Q

Metformin: Nutrient depletion

A

Malabsorption of B12 and B9

43
Q

Diuretics: Nutrient depletion

A

Increased urinary loss of Calcium, magnesium, potassium, folate, vits. B1, B6, C

44
Q

Antacids: Nutrient depletion

A

Increased gastric pH may reduce solubility and absorption. Aluminiumcontaining antacids can bind to calcium preventing absorption: Calcium, iron, chromium, folate

45
Q

Thyroxine: Nutrient depletion

A

Increased bone turnover may lead to increased urinary calcium losses: Ca

46
Q

OCP: Nutrient depletion

A

Reduced absorption, increased excretion, increased protein binding and induction of liver enzymes. Shift from plasma to tissues. Reduced absorption or interference with conversion to active form.
Reduction in activity of the thiaminedependent enzyme. Reduced liver storage of vit. A. Reduced B12 protein binding. Increased requirement
Folate Magnesium Vitamin B6 Vitamin B2 Vitamin B1 Vitamin A Vitamin B12 Vitamin C Zinc

47
Q

Alcohol and Drugs

A

Alcohol can inhibit a drug’s metabolism by competing with the drug for the same set of metabolising enzymes:

  • Long-term alcohol ingestion may activate drug-metabolising enzymes, thus decreasing the drug’s availability and diminishing its effects.
  • Enzymes activated by chronic alcohol consumption transform some drugs into toxic chemicals that can damage the liver or other organs

Alcohol can magnify the inhibitory effects of sedative and narcotic drugs at their sites of action in the brain (codeine, morphine, fentanyl):

  • Some drugs affect the metabolism of alcohol, thus altering its potential for intoxication and adverse effects: e.g., cimetidine (reduces stomach acid) appears to inhibit the enzyme needed to break down alcohol (alcohol dehydrogenase).
  • Alcohol can also force certain drugs (slow-release ‘depot’ injections) out of their depot (storage in muscle) resulting in overdose; this can happen with some antipsychotic drugs

Nutrition 2 - Semester ! (89 decks)

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