CELLULAR METABOLISM : A FEW NUMBERS

🔹Each molecule of ATP can produce 7.6 kcal of energy

🔹Aerobic metabolism of 1 mol of glucose generates 38 mol of ATP.

🔹A total of 288 kcal is produced per 1 mol of glucose. Ideally it can liberate 686 kcal; so this process is only 42% efficient.

🔹 Under aerobic conditions, during glycolysis,  2 ATPs are used but 4 ATPs and 2 NADH are generated. Under anaerobic conditions, NADH is not produced. 

🔹 A total of 325 g of glycogen is stored within skeletal muscle (75%) and the liver (25%).  Only 3% of the total energy available from glucose is utilised in the process of glycogenolysis; So storage of glucose as glycogen is highly efficient 

🔹 The HMP shunt produces Carbon dioxide, ribose-5-phosphate and NADPH but '0' ATP.

#biochemistry , #glycolysis , #physiology , #anesthesia

IMPORTANT FACTORS THAT AFFECT DRUG METABOLISM IN THE ELDERLY DURING ANESTHESIA

🚨Hepato-portal blood flow and hepatic enzymatic activity decrease 

🚨Plasma albumin level is reduced as you age, and for plasma protein-bound drugs this will lead to an increased proportion of unbound, active drug.

🚨Glomerular filtration rate falls by approximately 1% per year beyond the age of 30

🚨Opioid receptors decrease in number and increase in affinity ( The importance of this factor is less than the above mentioned ones, in case of opioid toxicity in elderly)

🚨IMPORTANT: lean body mass, body fat and total body water all fall. The volume of distribution of most drugs is therefore reduced. B͎u͎t͎ t͎h͎e͎ T͎O͎T͎A͎L͎ B͎O͎D͎Y͎ W͎A͎T͎E͎R͎ ( and muscle mass) d͎e͎c͎r͎e͎a͎s͎e͎s t͎o͎ a͎ g͎r͎e͎a͎t͎e͎r͎ e͎x͎t͎e͎n͎t͎ t͎h͎a͎n͎ t͎h͎e͎ T͎O͎T͎A͎L͎ B͎O͎D͎Y͎ F͎A͎T͎. 

⚙So drugs that are water-soluble, are affected more

🚨Elderly patients may be particularly sensitive to remifentanil, as a large proportion of its metabolism is catalysed by muscle-based esterases.

#DrugToxicity , #geriatrics , #anesthesia , #pharmacology