Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Yr 3 - January lectures 19 > Prescribing in special groups: 1 > Flashcards

Prescribing in special groups: 1 Flashcards

1
Q

Should pregnant women stop their medications for chronic disorders?

A

usually better not to stop = disease may adversely affect the pregnancy

  • other drugs, remedies or alcohol may be more toxic
  • less than 30 medicinal molecules are genuine human teratogens
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the reasons for changes in compliance/concordance in pregnancy?

A

doubt about drug use, side effects, disappearance of the complaints for which drugs prescribed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How does the absorptions change in pregnancy?

A

nausea and vomiting

  • increase gastric pH
  • reduced gastric emptying
  • increased gut transit time

increased absorption from IM injections and inhalation

therefore increased bioavailability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does metabolic pharmacokinetics change in pregnancy ?

A 
hepatic blood flow 
increased/decreased P450
increased UGT
p glycoprotein 
n-demthylation 
therefore increased drug metabolism
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How does distributive pharmacokinetics change in pregnancy?

A 
increased ECF
increased plasma vol
reduced albumin 
increased fat 
increased vol distribution 
reduced concentration 
therefore increase in drug protein binding
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How does elimination pharmacokinetics change in pregnancy?

A

renal blood flow and GFR = increased clearance of renally excreted drugs
hepatic blood flow and cholestasis
=> increased drug elimination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What drugs do you need to be careful with in pregnancy?

A

those with narrow therapeutic index
- e.g. antiepileptic drugs, enoxaparin
drug dosing may need to be altered
drugs conc / clinical effects need to be monitored

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a teratogen?

A

substance, organism, physical agents or deficiency state capable of inducing abnormal structure of function:

  • gross structural abnormalities
  • functional deficiencies
  • intrauterine growth restriction
  • behavioural aberations
  • demise
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What % of drugs are known teratogens?

A

1%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does teratogenicity refer to?

A

potential for a drug to cause foetal malformations and affects the embryo 3-8 weeks after conception

  • drugs can cause congenital malformations
  • 3rd-8th weeks periods of highest risk as organ systems are formed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the pre-embryonic phase and why is it relevant?

A

days 0-14 after conception - “all or nothing effect”

- leads to recovery or spontaneous loss

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What can take teratogens in the 2nd and 3rd trimester?

A

can affect growth (IUGR) and functional development or have toxic effects on tissues (fetotoxicity)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What should you assume when prescribing in pregnancy?

A

assume all drugs cross the placenta unless they have a high molecular weight (heparins)

  • avoid drugs in the first trimester
  • only prescribe if expected benefits outweighs risk of fetus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What drugs should be avoided in 1st trimester?

A 
androgens 
cytotoxic drugs 
lithium 
quinolone antibiotics
retinoids
sodium valporate
thalidomide
warfarin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What drugs should be avoided in the 2nd and 3rd trimester?

A

ACE inhibitors and ARBs - oligohydramnioa, growth retardation, impaired neonatal blood pressure control
Aminoglycosides - 8th nerve damage
NSAIDs and aspirin - haemorrhage and premature closure of ductus arteriosus
Opiates and benzos - reps depression
sulphonamides - hyperbilirubinaemia
tetracyclines - yellow discolouration of teeth, inhibits bone growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does physiological changes in pregnancy mean for maternal drug concentrations?

A

usually lower than in non-pregnant women taking the same dose
therefore in pregnancy drug doses may need to be increased

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What important elements should you consider when prescribing medicines to pregnant women?

A 
is it necessary?
does a specialist need to review?
are pregnancy guidelines available?
consider stage of pregnancy, past therapies and contra-indications 
ensure lowest dose used 
consider additional monitoring
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What age does the DoH recommend babies should be exclusively breastfed until?

A

until 6 months old

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does safety of drug use whilst breastfeeding depend on?

A

passage of a drug into breast milk, subsequent absorption in the infant, adverse drug reaction profile, infant age, infant co-morbidities, effective clearance of the drug

20
Q

Can drugs pass through breast milk?

A

yes - but most drugs pass in small quantities and are not a concern
- neonates (particularly premature infant) are at greater risk from exposure to drugs via breastmilk, owing to immature excretory functions and the consequent risk of drug accumulation

21
Q

What is the potential harm can be inferred from taking a drug while breastfeeding?

A

amount of active drug delivered to the infant
efficiency of absorption, distribution and elimination of drug by infant
effect of the drug on the infant

22
Q

What drug characteristics reduce passage of drug across into breast milk?

A

high molecular weight drugs - insulin and heparins
high protein binding - warfarin, NSAIDs
low lipid solubility - loratadine
lower pH - amoxicillin (ph of breast milk is 6.9, lower than in the plasma so conc of acidic drugs in breast milk will be low)

23
Q

What drugs should be avoided in breast feeding?

A

amiodarone - risk from release of iodine
antithyroid drugs - neonatal goitre and hypothyroidism
benzos
lithium salts
radioactive iodine
statins
sulphonamides

24
Q

What effect do drugs affecting dopamine activity have on breastfeeding?

A

dopamine agonists = decrease milk production
dopamine antagonists = may promote lactation when inadequate

some drugs can even inhibit infant suckling reflex e.g. phenobarbital

early postpartum, oestrogen can reduce milk vol therefore progesterone contraceptives are initially recommended

25
Q

What should children not be considered as of which 18-70 year old adults are?

A

children are not a homogenous group - variable and diverse subsets due to striking changes from neonate through childhood to adolescence

26
Q

What does unlicensed use of drugs mean?

A

clinical need cannot be met by licensed drugs
therefore drugs in different doses or for different indications are used
needs to be supported by evidence and experience
off-label prescribing is common practice in children
off label prescribing is common practice in children

27
Q

Why does oral pharmacokinetics need to be considered in children?

A

developmental changes in absorptive surfaces of the gut, GIT, and intraluminal pH can alter rate and extent of drug absorption

absorption is affected by slower gastric emptying times which takes 6-8 months to reach adult levels

first pass metabolism increased for some drugs in children

28
Q

Why does intramuscular pharmacokinetics need to be considered in children?

A

IM absorption is erratic due to reduced muscle mass and variability of blood flow to and from injection site

29
Q

Why does percutaneous pharmacokinetics need to be considered in children?

A

increased the younger the patient is due to thinner stratum corneum and increased skin hydration

30
Q

Why does water soluble drugs pharmacokinetics need to be considered in children?

A

higher volume of distribution = lower concentration of drug
therefore for comparable plasma and tissue concentration, higher doses per kg of body weight must be given to infants and children than to adults of some drugs e.g. gentamicin

31
Q

Why does plasma bound drugs pharmacokinetics need to be considered in children?

A

plasma proteins (albumin) are reduced in neonates
reduced plasma-protein binding causes an increase in free drug
drugs with greater unbound conc in plasma inc. morphine, phenytoin and diazepam
some other drugs such as sulphonamides can displace bilirubin from albumin resulting in more profound neonatal jaundice

32
Q

How does the distribution of body water and fat vary in children?

A

younger child the greater their total body water as weight %

premature - 85% body water, 1% fat
full term neonate - 70% body water, 15% fat
infant - 70% body water, 15% fat
child - 65% body water, 15% fat
young adult - 60% body water, 20% fat
older adult - 45 % body water, 10% fat
33
Q

How do hepatic enzyme pathways vary in neonates?

A

most phase 1 enzymes appear after birth but show a rapid postnatal maturation

phase 2 enzymes (glucuronidation and sulphation) development is less well understood

34
Q

What is GFR and renal function like in neonates?

A

immature taking up to 6 months to reach adult values
- GFR in neonate is 30-40% of that of an adult
drugs excreted by kidneys therefore accumulate - gentamicin (requires careful dosing and changes to dosing interval)
adjust dose regimens and monitor closely

35
Q

What is the calculation used to work out dosing in children?

A

dose = child’s body surface area /adult body surface area) x adult dose

formulae relates to bodyweight, age, or body surface area of child to adult dose

36
Q

What are the 3 different ways of expressing dosing for children?

A

age banding - usually for low therapeutic index drugs

weight
- for many different drugs

body surface area
- for narrow therapeutic index drugs

37
Q

What age are children classified as adults?

A

over 12 years but remember a lot of children will not have gone through puberty yet

38
Q

What do you do for emergency dosing in children?

A

emergency doses are often tabulated in reference documents
- broselow tape = uses child length to estimate weigh, combines dosing and equipment zones creating a simple visual system

39
Q

How are oral drugs administered in children?

A

certain formulations are tolerated better

  • liquids are better tolerated than tablets
  • flavoured oral medication can be helpful
  • sugar free prescriptions should be used (Reduces dental cavities)
  • remind parents that suspensions contain undissolved particles and should always be shaken before use
40
Q

What are some other routes other than oral for administering drugs to children?

A

IV = better tolerated than IM
IM = discouraged in neonates and young due to lack of suitable muscle and unpredictable absorption
rectal route can be used if oral not tolerated
inhalational medications are useful

41
Q

How do you ensure appropriate measuring of meds in children?

A

need syringe or calibrated measuring spoon
- household teaspoons vary too much

also important not to add meds to feeds as this can cause interactions, also if they dont finish the drink for example they’ll be under dosed

however some medications can be added to milk or juice

42
Q

What are some special routes of admin?

A

intraosseous = IO

  • access uses highly vascularised bone marrow to deliver fluids and drinks
  • good in emergency

Buccal = non invasive route for appropriately permeable drugs e.g. buccal midazolam

43
Q

Are under 16s able to consent to medication?

A

yes if they can come to a clear decision and understand the treatment

44
Q

How can you avoid harm from medicines in children?

A

dosing issues - always check age, weight, BSA against doses
-round doses sensibly
- liquid forms should be prescribed in mg
children resistant packaging

45
Q

What drugs should be avoided in children?

A

IV chloramphenicol =>grey baby syndrome - rare adverse effect in neonates causing cyanosis, grey skin colour, reduced BP, cardiovascular collapse

Aspirin => reye’s syndrome
- aspirin not given to children <16 as it causes mitochondrial damage leading to rash, vomiting and liver damage

Tetracycline => growing teeth and bone - not given <12 - discoloured teeth and growth problems

Yr 3 - January lectures 19 (30 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions