Pharmacology Flashcards

1
Q

Teratogens cause abnormalities within the baby following fetal exposure during preg. In what part of preg is the most vulnerable?

A

First half of pregnancy is the most vulnerable- affect embryogenesis

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2
Q

What are some preventable teratogens?

A

Alcohol- fetal alcohol syndrome

Smoking- low birth weight, preterm birth, cerebral palsy, learning difficulties

Marijuana, ecstacy, cocaine- low birth weight, withdrawal symptoms, learning and behavioural problems

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3
Q

What is pharmacokinetics?

A

What the body does to a drug

Movement of the drug through, and out of the body

The time course - absorption, bioavailability, distribution, metabolism, and excretion.

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4
Q

What is pharmacodynamics?

A

Response of the body to the drug. It refers to the relationship between drug concentration at the site of action and any resulting effects namely, the intensity and time course of the effect and adverse effects

Biochemical /physiologic/ molecular effects of drugs on body
Receptor binding/post receptor effect

Pregnancy may affect the site of action and receptor response to drugs
Efficacy of medicine may be different
Adverse effects may also be different

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5
Q

What is used for N&V (1st & 2nd line)?

A

Cyclizine- antihistamine
Prochloroperazine- phenothiazine
Doxylamine/pyridoxine combination product (Xonvea®) was licensed for the treatment of NVP in the UK in 2018 and can also be offered as a first-line option.

Second line- ondansetron, metoclopramide

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6
Q

What meds can be used for HT in preg?

A

Labetolol, nifedipine, methyldopa, hydralazine

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7
Q

What are some teratogenic medicines for HT that should be changed as soon as preg is confirmed?

A

ACE inhibitors, angiotensin receptor antagonist

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8
Q

In pregnancy there is a change in free serum conc of antiepileptics: what are the safest meds for epilepsy in preg?

A

Carbamazepine and lamotrigine

Always give high dose folic acid

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9
Q

What are some antiepileptics that are not to be used in preg and why?

A

Phenobarbitone- cardiac malformations
Sodium valproate- NTD, facial clefts

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10
Q

What medications are safest in diabetes in preg?

A

Insulin – safest
Gestational diabetes/ type 2- metformin

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11
Q

Is LMWH safe in preg and in what context is it used?

A

Yes-thromboembolism

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12
Q

What medications are not safe in pregnancy for thromboembolism?

A

Warfarin- fetal warfarin syndrome/fetal embryopathy
(nasal hypoplasia and skeletal abnormalities, including short limbs and digits, and stippled epiphyses, is a well-recognised complication of first trimester warfarin use in pregnancy
Avoid in 1st and third trimester)

Directly-acting anticoagulants (DOACs, e.g. apixaban, dabigatran, edoxaban and rivaroxaban)- manufacturer advises to avoid-animal toxicity

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13
Q

What medications are recommended for asthma in pregnancy (risk of medication use are lower than risk of untreated asthma)?

A

B2 agonist- albuterol, salbutamol - safe
Inhaled corticosteroid- budesonide
Theophyline- potential toxicity
Systemic corticosteroid- severe asthama

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14
Q

What treatments are suitable and not in preg for headaches and migraines?

A

Paracetamol

Ibuprofen- persistent pulm hypertension- avoid in 3rd trimes

Sumatriptan- acute treatment of migraine

Propanolol lowest effective dose

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15
Q

Do morphine based medicines cause an increase in congenital abnormalities?

A

NO

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16
Q

What are the risks of morphine based meds in preg?

A

Risk of neonatal respiratory depression and withdrawal

Used as labour analgesia

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17
Q

Why should codeine be avoided during lactation

A

Avoid codeine during lactation- infant opiate toxicity

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18
Q

Antidepressants and antipsychotics: weigh risk vs benefits of treatment:

  1. SSRI
  2. Lithium
  3. Diazepam
  4. Quetiapine?
A

SSRI- Where the benefits of SSRI use outweigh potential risks, use of SSRIs during pregnancy may be indicated. The risks of destabilization and maternal relapse must be taken into account when considering discontinuing SSRIs

Lithium- ebstein’s anomaly- cardiac anomaly

Diazepam- old studies clefts lip/palate- floppy infant syndrome

Quetiapine- large baby, poor neonatal adaptation syndrome

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19
Q

What are some examples of Abx that are safe and what are some to avoid?

A

Penicillin- generally safe- check allergy

Macrolide- azithromycin/erythromycin- use only if no alternative

Tetracycline- do not prescribe, animal studies- effects on skeletal development, discolouration of teeth

Sulphonamides- teratogenic-avoid in first trimester- folate antagonist

Aminoglycosides- auditory or vestibular nerve damage -The risk is greatest with streptomycin.

Cephalosporins- generally safe

20
Q

Why in cancer treatments should pregnancy be excluded before taking these meds?

A

Most cytotoxic drugs are teratogenic

Take specialist advice- if needed to start or continue treatment in pregnancy

21
Q

What are some covid treatments that have in general not showed to have increased risks in preg?

A
  • Hydroxychloquine
  • Azithromycin-macrolide Abx
  • Lopinavir/ritonavir-protease inhibitors
  • Corticosteroids
22
Q

What should always be checked when prescribing in preg?

A

Dose, side effects, interactions and effects in preg

23
Q

All drugs should be avoided in preg unless deemed essential: How is this approached in the case of epileptic medications?

A

Consider risk of not taking epileptic medication during pregnancy and the impact uncontrolled seizures can have on the baby. Benefits have to outweigh the risks.

24
Q

How is absorption affected in preg?

A

Physiological changes in a woman’s body during pregnancy can change how quickly a medicine is distributed and eliminated from her body. This can affect plasma drug levels and how well a medicine works.

Oral route may not be an option for women suffering N&V (consider buccal).

Decreased gastric emptying and gut motility – higher incidence of constipation, may not affect regular drug therapies but could impact once off treatments.

Increased absorption of intramuscular drugs due to increased blow flow.

Increased CO and reduced TV may cause increased absorption of inhaled drugs.

25
Q

Increase in plasma volume and fat will change the … of drugs; increasing the volume of …

A

DISTRIBUTION

Greater dilution of plasma will decrease the relative amount of plasma proteins, increasing the amount of free drug in circulation (less protein bound).

26
Q

What and how does enzyme alteration affect metabolism in preg and what are some examples?

A

Altered enzyme actions due to oestrogen and progesterone levels.

Liver P450 enzymes may be induced or inhibited which can lead to increased or reduced metabolism – drug dependent.

Examples
Phenytoin levels are reduced in pregnancy due to metabolism being induced (sped up).

Theophylline levels increase during pregnancy due to metabolism being inhibited resulting in more free drug in circulation for longer.

27
Q

GFR is increased in pregnancy by 50% leading to an increased … of many drugs.

A

EXCRETION

This can result in a reduction in plasma concentration and can require for higher medication doses being required for renally cleared drugs; eg. Gentamicin and Digoxin.

28
Q

Is the placenta a barrier to drugs?

A

NO

Nearly all drugs except those with a high molecular weight (eg. insulin and heparin) will cross the placenta to the fetus. In practice, virtually all drugs have the ability to affect the unborn baby.

29
Q

What is the role of the placenta and can alcohol and nicotine pass through?

A

Membrane - allows for the exchange of materials between mother and baby. The mother provides oxygen, glucose, fat, vitamins, and antibodies among other things to baby; baby transfers urea, CO2, and other waste products back to mother.

Alcohol and nicotine (smoking) passes through the placenta to the unborn baby. Often in practice now come across cocaine use and other recreational drugs.

30
Q

What do factors affecting placenta transfer of medicine depend on?

A

Drug type, lipid-soluble unionised drugs cross more readily than polar drugs; length of exposure, stage of pregnancy.

31
Q

ADME profile different in fetus to newborn baby.

In what ways does this differ in terms of D, M & E?

A

Distribution
Circulation is different.
Less protein binding than adults, more free drug.
Little fat, so distribution different.
More blood flow to brain.

Metabolism
Less enzyme activity, this increases with gestation.

Excretion
Drug excretion is into amniotic fluid and then swallowed and re-circulated.
Drugs and metabolites can accumulate in amniotic fluid due to this.

32
Q

What is a teratogen and what can it prevent? When is the biggest risk of exposures?

A

Teratogen is an agent or factor which can cause congenital malformation.

A teratogen can prevent implantation of the conceptus (embryo), cause abortion, produce intrauterine growth restriction or cause fetal death.

Biggest risk of exposures during the organogenesis period (3-10weeks). When organs are being formed.

33
Q

What are some examples of drugs that can cause fetotoxicity (toxic effects to the foetus)?

A

Drugs given after the first 2 months of pregnancy are more likely to cause general growth retardation, or interfere with functional development of organs.

Warfarin may cause intracranial haemorrhage if given in 2nd and 3rd trimester

NSAIDs taken in the 3rd trimester can cause premature closure of ductus arteriosus resulting in neonatal pulmonary hypertension

Beta Blockers given in late pregnancy may result in neonatal hypoglycaemia

34
Q

What are the prescribing principles for women of child bearing age?

A

Always consider the possibility of pregnancy (planned or not)

Warn women of potential risks

If planning a pregnancy, advice to discuss treatment options prior to stopping medication

Always discuss contraception

Pregnancy Prevention Programmes – legal requirement for some treatments, eg. Isotretinoin, valproate. MHRA guidance, confirmed with negative pregnancy test prior to prescribing

35
Q

What are the principles for prescribing drugs during preg?

A

Consider non-pharmacological treatments

Avoid all drugs in the first trimester if possible

Use the medicine with the best safety profile (avoid new drugs unless deemed safe)

Use the lowest effective dose for the shortest period of time

Consider the need for dose changes and additional therapeutic monitoring for some drugs

Don’t under treat a condition, this may be more harmful to mum and baby

36
Q

What is the 1st line for UTI in preg?

A

Nitrofurantoin (up to 36 weeks)

37
Q

What are some benefits of breast feeding for the baby?

A

Reduced risk of infections – GI infections, UTIs, otitis media, respiratory diseases, NEC (in preterm babies)

Neurological development – studies show link between BF and increases scores in cognitive function

Protection against later development of atopic diseases, eg. Eczema

Lower incidence of insulin-dependent diabetes

Lower incidence of SIDS – linked to neurological maturation

38
Q

What are some benefits of breast feeding for the mother?

A

Reduction in risk of pre-menopausal breast cancer, ovarian cancer and hip fractures

Less uterus bleeding, quicker return to it’s normal size

Prevents post-natal depression

Exclusively breastfeeding can provide contraception (LAM) – lactational amenorrhoea method (Needs to be fully breastfeeding, day and night on demand. Baby less than 6 months and periods have not returned to mother)

Faster weight loss from pregnancy weight gain
Saves money compared to formula

39
Q

Almost all drugs will cross into the breastmilk but there are various factors which impact this:
what are they?

A

Maternal factors – dosage regime; route of administration (IV higher conc than oral or topical), drug clearance by kidneys and liver (degrees of impairment may lead to accumulation)

Drug characteristics – degree of ionisation at physiological pH; lipid solubility (more lipid soluble drugs will penetrate into the breastmilk), protein binding, molecular weight (MW less than 200 appear rapidly in breastmilk, eg alcohol)

Breast physiology – volume of milk production and yield capacity of each breast varies – this will also show considerable variation between the amount of drug ingested by the baby.

40
Q

What are some factors to consider in maternal treatment during breast feeding?

A
  • Does the mother requirement drug treatment?
    -What is the safest option for the baby?
    -If there is the possibility of harm, what monitoring has to be carried out for the baby?
    -Can treatment be delayed until breastfeeding has stopped or baby starts to wean?
    -Avoid drugs with long half-lives, drugs that are highly protein bound are preferred
    -Can medication be taken immediately after feeding? Pump and Dump culture??
41
Q

What are some examples of drugs to avoid during breast feeding?

A

Cytotoxics
Immunosuppressants
Anti-convulsants (not all)
Drugs of abuse (consider recreational)
Amiodarone
Lithium
Radio-iodine

Need to consider what drugs would you use for treatment in neonates – they would tend to be safe if we would treat babies with them. Levels would be much smaller in breastmilk than used to treat.

42
Q

What are some drugs that can enhance/suppress lactation?

A

Cabergoline – inhibition of lactation

Metoclopramide – enhancement of lactation

Prolactinoma (enhancement of milk production).

Also Domperidone is an option

43
Q

What is the guidance for herbal and OTC meds in breast feeding?

A

‘no information’ does not mean ‘safe’.

Very limited scientific data for herbal medicines, should ideally be avoided during lactation. Some herbal medicines can have hormonal effects.

Important to ask about all medication taken by mother, not just prescribed medicines.

44
Q

What are the principles of prescribing in breast feeding?

A

Avoid unnecessary drug use – always consider non-pharmaceutical options

Always check up to date information resources
If medicine is licensed and safe for use in paediatrics/neonates; then it is likely to be safe to be used during breastfeeding (amount in milk will be less than treatment doses used in baby)

Try to choose drugs with pharmacokinetic properties which reduce infant exposure to drug eg, highly protein bound drugs

Always weigh up the benefit of breastfeeding to mother and infant – should never discourage feeding unless in extreme circumstances
Extreme circumstances – cancer diagnosis, substance misuse, lithium – mental health conditions

45
Q

What are some issues associated with regular DHC?

A

Constipation
Dependence
Drowsiness