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pharmacology > drug administration and drug action > Flashcards

drug administration and drug action Flashcards

1
Q

definition of ‘routes of administration’

A

The method through which the dosage form is administered into the body for treatment of various diseases and disorders so that it reaches the desired state of action.

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2
Q

Define the route the drug takes when drugs are administered orally.

A

The drug is absorbed into the systemic circulation by passing through the gastrointestinal tract.

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3
Q

Advantages of the oral route. (3)

A
  1. Convenient. The patient can self-administer such medications and it is the easiest route of administration.
  2. Cheap. It is the cheapest route compared to most parental routes, non-invasive and does not require additional devices.
  3. Absorption. It takes place along the organs of the gastrointestinal tract.
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4
Q

Disadvantages of the oral route. (6)

A
  1. First-pass metabolism effect. Drugs transported orally are initially transported to the liver via the portal vein where they undergo metabolism through various hepatic enzymes, and the concentration of drug at the site of action is less to achieve desired therapeutic action.
  2. Drugs absorbed orally may cause irritation to the gastric mucosa which may lead to nausea and vomiting.
  3. Most drugs are influenced by gastric acid and digestive juices e.g insulin
  4. Slow onset of action hence cannot be used during emergencies.
  5. Cannot be used on an unconscious patient.
  6. Palatability issues due to bitter taste and odour.
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5
Q

Define the sublingual route.

A

The drug is absorbed through the buccal mucous membrane and directly enters the systemic circulation, bypassing the first-pass effect. e.g nitroglycerin buccal tablet

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6
Q

advantages of the sublingual route. (2)

A
  1. Quick onset of action and the action can be terminated by spitting it out.
  2. Self-administration is possible by the patient himself
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7
Q

disadvantages of the sublingual route.

A
  1. Palatable issues due to bad smell and taste.

2. The drug is not suitable for irritable and lipid-insoluble drugs.

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8
Q

explain the buccal route.

A

The formulation is placed between the gums and cheek. The drug gets rapidly absorbed by the buccal mucosa and directly enters the systemic circulation avoiding the first-pass metabolism. The route provides a localized effect.

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9
Q

Buccal dosage forms. (2)

A
  1. Buccal tablets e.g prochlorperazine maleate tablets for after surgery.
  2. Chewing gum e.g Nicotine gum used to overcome drug addiction.
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10
Q

Advantages of the buccal route.(2)

A
  1. Rapid absorption of drugs directly to the systemic circulation.
  2. Avoids first-pass metabolism
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11
Q

disadvantages of the buccal route.

A
  1. poor patient compliance due to palatable issues like bad smell and taste.
  2. Causes irritation of the oral mucosa.
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12
Q

Explain the rectal route.

A

The drugs are administered in the form of suppositories and pessaries. The walls of rectum are thin and highly rich in blood supply hence the drug is readily absorbed.

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13
Q

disadvantages of the rectal route. (2)

A
  1. Poor patient compliance as it is uncomfortable.
  2. Drug absorption may remain incomplete and be undesirable because sometimes the suppositories do not melt under rectal temperature resulting in loss of drugs.
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14
Q

Explain the vaginal route.

A

Drugs can be administered to women in forms of solutions, gels, rings, suppositories, tablets, cream or pessaries.
e.g suppositories, vaginal pessaries and urethra; bogies.

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15
Q

Explain the topical route

A

The drug is directly applied on the skin or mucous membrane at various sites for local action.

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16
Q

Ways in which the topical route is applied in the oral cavity(4)

A
  1. Suspension e.g nystatin for ulcer.
  2. Ointment e.g clotrimazole for oral candidiasis.
  3. Spray especially used by dentists to provide localized anaesthetic effect e.g 5 per cent lignocaine hydrochloride.
  4. As a tablet that is affected by gastrointestinal factors e.g neomycin is applied for sterilization of gut before surgery
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17
Q

ways in which the topical route is applied in the renal and anal canal.

A

The administration is applied in the form of an enema

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18
Q

Definition of Enema

A

This is the administration of a drug in liquid form. e.g evacuant enema for the evacuation of the bowel or a retention enema used in ulcerative colitis during the time of colonoscopy

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19
Q

ways in which the topical route is applied in eye, ear and nose

A

The formulation is applied in forms of drops, ointments and sprays e.g gentamicin eye/ear drops.

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20
Q

way in which topical route is applied in the bronchi.

A

This is applied through inhalation e.g salbutamol ipratropium bromide etc for bronchial asthma and chronic obstructive pulmonary disease

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21
Q

way in which topical route is applied on skin.

A

Applied either as an ointment, cream, lotion or powder (anti fungal) for skin infections

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22
Q

Define the parental route.

A

this is when the drug is not administered via the gastrointestinal tract as it directly enters the systemic circulation

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23
Q

Advantages of the parental route. (6)

A
  1. Quick onset of action of drugs hence can be used during emergencies.
  2. Useful in administration to an unconscious patient.
  3. Most suitable for uncooperative and unreliable patients.
  4. It can be given to patients with vomiting and diarrhea.
  5. It is suitable for irritant, bitter and unpalatable drugs.
  6. This can be used for drugs with high fast pass metabolism so that the bioavailability of the drug is retained.
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24
Q

Disadvantages of the parental route. (5)

A
  1. Parenterals require highly aseptic conditions.
  2. Preparations need to be sterile and expensive.
  3. The technique is invasive and sometimes very painful.
  4. Such a route is not meant for self administration.
  5. Can cause local tissue injuries to nerves, vessels, phlebitis, local damage etc.
25
Q

Describe the intravenous route (IV)

A

the drug is directly administered into a vein as a direct injection or infusion.

26
Q

intravenous dosage forms (4)

A
  1. Injection
  2. Emulsion injection
  3. Solution for injection.
  4. Solution for infusion
27
Q

Advantages of the intravenous route. (7)

A
  1. It has an immediate onset of action hence suitable for emergencies.
  2. It can be given to an unconscious patient.
  3. Best for drugs with high fist pass metabolism as it avoids the first-pass metabolism.
  4. This route helps to achieve predictable and precise control over drug-plasma concentration as compared to other routes.
28
Q

disadvantages of the intravenous route. (7)

A
  1. Possible anaphylaxis. (allergic reactions)
  2. Risk of infection.
  3. Procedure is painful especially for children.
  4. It has a risk of phlebitis (swelling of veins) or extravasation
  5. It requires trained medical/nursing staff to administer the drug.
  6. Once injected the drug cannot be removed from the systemic circulation.
  7. It is a highly labor-intensive and time consuming process.
29
Q

Define the intramuscular route.

A

The drug is directly administered to the muscles e.g. gluteus Medius or deltoid.

30
Q

advantages of the intramuscular route. (4)

A
  1. Immediate onset of action.
  2. depot or sustained release effects of drugs that can be used for chronic diseases.
  3. Avoids fist pass metabolism.
  4. Easier to administer as compared to the intravenous route of administration.
31
Q

Disadvantages of the intramuscular route. (4)

A
  1. Expensive
  2. Requires trained medical/nursing staff.
  3. Irritating drugs may be painful.
  4. The drug absorption is variable and dependent upon the muscle group used and the blood flow to the muscle.
32
Q

define the subcutaneous route.

A

The drug is directly administered to the subcutaneous tissue through direct infusion or injection

33
Q

Advantages of the subcutaneous route. (3)

A
  1. Can be self administered by the patient.
  2. Best suited for drugs having a long duration of action as it reduces the duration of action e.g. flupentixol used in depression.
  3. Low risk of systemic infection
34
Q

disadvantage of subcutaneous route (1)

A
  1. Absorption of drug is variable depending on blood flow.
35
Q

Define the otic/ear route.

A

The drug is administered into the ear using formulations such as ear drops.

36
Q

Advantage of the ear route(1)

A
  1. It produces a localized effect
37
Q

Disadvantages of the otic/ear route (2)

A
  1. Self-administration is difficult in this route.

2. The route may be considered time-consuming by the patient (as they need to be in a tilted position for a few minutes.

38
Q

Define the ocular/eye route

A

The drug is administered into the eye using formulations such as eye drops

39
Q

Advantages of the ocular route. (2)

A
  1. The localized effect is achieved.

2. Systemic side effects are reduced.

40
Q

Disadvantages of the ocular route. (3)

A
  1. Eye drops may lead to temporary blurring of vision.
  2. There may be some barriers to administration e.g. poor vision.
  3. People with contact lenses are not permitted to use all ocular dosage forms
41
Q

Define the the inhalation route

A

Volatile liquids and gases are given by inhalation for systemic effects or treatment of nasal disorders

42
Q

Advantages of Inhalation. (3)

A
  1. Quick onset of action.
  2. The amount of dose is less hence systemic toxicity is minimized.
  3. The number of drugs administered can be regulated.
43
Q

disadvantages of inhalation.

A

Local irritation in the nasal cavity may cause increased respiratory secretions and bronchospasm.

44
Q

What can be described as drug response.

A

When the desired amount of drug reaches its desired site without undergoing alteration in the systemic circulation.

45
Q

why do children under 12 years usually require a fraction of an adults dose?

A
  1. This is because of the drug metabolism enzyme system i.e. the biotransformation process is inefficient in them.
  2. Their barriers are not fully developed hence any drug can cross the blood brain-barrier and enter the brain.
  3. Infants have an immature renal excretory system hence some drugs cannot be excreted.
  4. The hepatic metabolism capacity is underdeveloped.
46
Q

Reasons why the drug dosage of a newborn is reduced (4)

A
  1. The process of gastric acid secretion is not fully developed e.g. the absorption of ampicillin and amoxicillin in the gastrointestinal tract is greater to neonates due to decreased gastric acidity.
  2. Deficiency of liver microsomal enzymes (glucuronic transferase)
  3. Low plasma protein binding.
  4. Glomerular filtration rate and tubular secretions are not adequate
47
Q

explain the psychological changes that need to be considered while calculating the dose of the Geriatric age group (>60) (6)

A
  1. Reduction in body weight and low amount of fat.
  2. Decreased gastric emptying, intestinal motility and mesenteric blood flow
  3. Poor renal and hepatic functions.
  4. Altered mental functions.
  5. They are prone to suffer from adverse drug reactions and, for them, liquid medications are preferred.
  6. Liver functions are impaired in geriatrics e.g. drugs like diazepam have a half life of 2 hours in normal adults compared to 90 hours in geriatric patients.
48
Q

Why do males and females behave, most often, variably to drug effects.

A

The activities of the microsomal enzymes vary with the changes in hormones such as androgens and estrogens’ which leads to an alteration in drug sensitivity e.g. testosterone increases rate of metabolism of drugs hence causing an alteration in drug sensitivity.

49
Q

why is there a decreased metabolism of some drugs in females

A

Females are prone to autonomic drugs that is, oestrogen that inhibits choline esterase enzyme in females, thereby increasing acetylcholine ASH in females and their related effects

50
Q

What are the properties of drugs affected by the maternal changes in the body’s physiology during pregnancy

A
  1. The excretion process such glomerular filtrate rate (GFR) and the renal elimination of drugs.
  2. The volume of distribution of drugs and their respective distribution in various parts of the body.
  3. Biotransformation of some drugs
  4. Cardiac output is affected during gestation (the period of time between conception and birth)
51
Q

what are the properties of drugs that are dependent for the passage of drugs through the placenta (2)

A
  1. Lipid solubility

2. The degree of drug ionisation.

52
Q

list some of the physiological and biochemical functions that alter drug dosage and effects with the help of the circadian rhythm.

A
  1. Variations in hepatic drug metabolizing enzymes.
  2. Changes in neuronal activity.
  3. Different drug distribution patterns.
  4. Changes in hormonal profiles and in central receptor density due to drug administration at different times.
53
Q

Explain the cheese reaction.

A

this is when a patient who is on treatment with monoamine oxidase (MAO) inhibitors takes tyramine rich foods like cheese and alcohol which may lead to hypertensive crisis.

54
Q

what are drug interactions.

A

These are the changes in the effect of drugs due to recent or concurrent use of another drug (drug-drug interactions), ingestion of food(drug-nutrient interactions) or the ingestion of dietary supplements (dietary supplements-drug interactions)

55
Q

consequences of such drug interactions. (3)

A
  1. an increase in the response of one or both drugs (synergism).
  2. a decrease in response of one or both drugs.
    (antagonism)
  3. An unexpected change in response to one or both drugs
56
Q

the pharmacokinetics interactions are classified into? (4)

A 
Absorption
distribution
metabolism
excretion interactions 
(ADME)
57
Q

Explain the two types of drug interactions in pharmacodynamics.

A
  1. Potentiation. sometimes known as synergism in which the response is increased due to synergistic effect.
  2. Antagonism. This is the chemical, physiological or pharmacological, and physico-chemical incompatibility of drugs reducing effects of one or both drugs.
58
Q

The difference between synergism and antagonism

A

Synergism - this is wen two drugs with similar pharmacological or side effects are given together to produce an additive effect.
Antagonism - One drug antagonizes the pharmacological action of another when given together

pharmacology (5 decks)

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