SS_PA 1.24 : paediatric physiology

Not a bad textbook, Evers & Maze… But rubbish for paediatric pharmacodynamics… So I’ve swapped over to some paediatric physiology instead. I used Miller as it was handy.

SS_PA 1.24 Describe the physiology of the cardiovascular, respiratory, renal and neurological systems in the neonate and the changes that occur with growth and development and the implications of this for anaesthetic care

During the first 2 weeks of age a neonate can flip back into a foetal circulation   TRUE/FALSE

The neonate has more compliant ventricles than an adult   TRUE/FALSE

Infants have more type I muscle fibres in their diaphragm   TRUE/FALSE

Neonates have decreased intracardiac calcium stores   TRUE/FALSE

Oxygen consumption in infants is higher than in adults   TRUE/FALSE

SS_PA 1.51 : paediatric pharmacokinetics

As promised…

SS_PA 1.51  : Describe how the pharmacokinetics of drugs commonly used in anaesthesia in neonates and children differ from adults and the implications for anaesthesia

Neonates require larger doses of neuromuscular blockers per kg than adults   TRUE/FALSE

Neonates require larger doses of remifentanil per kg than adults   TRUE/FALSE

Neonates require a larger induction dose of thiopentone per kg than adults   TRUE/FALSE

Higher doses of EMLA can be more safely used in neonates than older children   TRUE/FALSE

Surgical stress decreases the concentration of alpha 1 acid glycoprotein   TRUE/FALSE

SS_PA 1.51 : paediatric pharmacokinetics

Staying on the theme of routes of administration today..

SS_PA 1.51  : Describe how the pharmacokinetics of drugs commonly used in anaesthesia in neonates and children differ from adults and the implications for anaesthesia

Oral medications are absorbed slowly in infants due to decreased gastric emptying and intestinal motility  TRUE/FALSE

Nasal midazolam tastes good  TRUE/FALSE

Gastric pH is lower in infants than in adults  TRUE/FALSE

The solubility coefficients of an inhaled anaesthetic will determine its volume of distribution  TRUE/FALSE

In Evers & Maze the author states  ‘Other factors causing a more rapid “wash-in” of inhalational anesthetics include the greater fraction of cardiac output distributed to the vessel-rich tissue group (e.g., the lungs)’ What do you think of this comment?

(hint – keep reading this chapter on paediatric pharmacology – you might even be able to spend the rest of the week testing your retention of the material)

 

 

BT_PM 1.15 : Routes of opioid administration

It’s such fun being able to use so many different routes to administer drugs in our jobs. So many doctors out there don’t get our opportunities.

BT_PM 1.15  Discuss the pharmacokinetic and clinical implications of different routes of administration for commonly used opioids, including the oral, transdermal, subcutaneous, intramuscular and intravenous routes, and with particular reference to fentanyl, morphine, methadone, tramadol and codeine

Fentanyl undergoes significant first pass pulmonary uptake and metabolism.  TRUE/FALSE

The cytochrome P450 3A4 (CYP3A4) is predominantly responsible for the metabolism of Alfentanil.   TRUE/FALSE

Alfentanil undergoes extensive hepatic metabolism that demonstrates extensive interindividual variability   TRUE/FALSE

The bioavailability of sublingual buprenorphine is similar to that of parenteral buprenorphine   TRUE/FALSE

Epidural fentanyl undergoes a biphasic absorption pattern   TRUE/FALSE

 

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Treasure life

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Today in South Australia we will commemorate and celebrate the life of one of our young registrars, who died unexpectedly last week from a sudden medical problem.

Life is fragile, treasure it.

 

BT_PO 1.52 and 1.53 Adrenergic agonists

You may have spotted a couple of these little creatures whilst undertaking yesterday’s quiz.

These drugs lend themselves very well to a discussion of structure activity relationships, as there a large number of ways the basic catecholamine structure has been altered, to produce a range of drugs with different pharmacokinetic and pharmacodynamic properties

BT_PO 1.53 describe the pharmacology of adrenergic agonists

Here is one true statement to get you oriented:

Phenylethylamine can be considered the parent drug on which all sympathomimetics are based.

Here is the molecule with the carbons numbered

Phenylethylamine_numbered.svg

 

Maximal  ⍺ and B potency is conferred by OH substitutions on the 3′ and 4′ positions of the benzene ring T/F

Sympathomimetics can be chiral around either the ⍺ or B carbon T/F

A very large substitution on the terminal amine promotes B1 selectivity T/F

A methyl substitution at the ⍺ carbon prevents metabolism by monoamine oxidase and prolongs duration of action T/F

Absence of hydroxyl groups on the benzene ring improves oral bioavailability by preventing metabolism by COMT T/F

A little structure quiz

You are unlikely to have to draw a drug molecule in the vivas, it’s time consuming and doesn’t really demonstrate understanding.

You may have to identify something with a simple structure,  but mostly you will be told what the drug you are presented with is.

However, I think it is good to think about a drug’s structure and how that influences activity ( there are even some LOs specifically related to structure-activity BT_GS 1.23 and BT_GS 1.29 )

Below are some drugs for you to have a go at identifying. Whilst you take this quiz, have think about how the drug’s structure helps confer its activity.

I’ll post some answers on the weekend

  1.  

SS_OB 1.13 Placental transfer of drugs

Other end of the age spectrum today..

SS_OB 1.13 Explain the factors that influence the transfer of drugs across the placenta

Ionised drugs are more likely to cross the placenta compared with non-ionised drugs T/F

Heparin is safe to use in pregnancy because its large molecular size prevents it crossing the placenta T/F

Weakly basic drugs, with a pKa less than 7.4, may become concentrated in the fetal compartment secondary to increased levels of ionisation T/F

The placenta is capable of metabolising some drugs presented to it T/F

For highly lipid soluble drugs, degree of protein binding is an important factor in the rate of placental drug transfer T/F