Last week, the Australian Therapeutic Goods Administration added intravenous (IV) fluids to the growing list of medicines in short supply. The shortage is due to higher-than-expected demand and manufacturing issues.

Two particular IV fluids are affected: saline and compound sodium lactate (also called Hartmann’s solution). Both fluids are made with salts.

There are IV fluids that use other components, such as sugar, rather than salt. But instead of switching patients to those fluids, the government has chosen to approve salt-based solutions by other overseas brands.

So why do IV fluids contain different chemicals? And why can’t they just be interchanged when one runs low?

We can’t just inject water into a vein

Drugs are always injected into veins in a water-based solution. But we can’t do this with pure water, we need to add other chemicals. That’s because of a scientific principle called osmosis.

Osmosis occurs when water moves rapidly in and out of the cells in the blood stream, in response to changes to the concentration of chemicals dissolved in the blood plasma. Think salts, sugars, nutrients, drugs and proteins.

Too high a concentration of chemicals and protein in your blood stream leads it to being in a “hypertonic” state, which causes your blood cells to shrink. Not enough chemicals and proteins in your blood stream causes your blood cells to expand. Just the right amount is called “isotonic”.

Mixing the drug with the right amount of chemicals, via an injection or infusion, ensures the concentration inside the syringe or IV bag remains close to isotonic.

What are the different types of IV fluids?

There are a range of IV fluids available to administer drugs. The two most popular are:

• 0.9% saline, which is an isotonic solution of table salt. This is one of the IV fluids in short supply
• a 5% solution of the sugar glucose/dextrose. This fluid is not in short supply.

There are also IV fluids that combine both saline and glucose, and IV fluids that have other salts:

• Ringer’s solution is an IV fluid which has sodium, potassium and calcium salts
• Plasma-Lyte has different sodium salts, as well as magnesium
• Hartmann’s solution (compound sodium lactate) contains a range of different salts. It is generally used to treat a condition called metabolic acidosis, where patients have increased acid in their blood stream. This is in short supply.

What if you use the wrong solution?

Some drugs are only stable in specific IV fluids, for instance, only in salt-based IV fluids or only in glucose.

Putting a drug into the wrong IV fluid can potentially cause the drug to “crash out” of the solution, meaning patients won’t get the full dose.

Or it could cause the drug to decompose: not only will it not work, but it could also cause serious side effects.

An example of where a drug can be transformed into something toxic is the cancer chemotherapy drug cisplatin. When administered in saline it is safe, but administration in pure glucose can cause life-threatening damage to a patients’ kidneys.

What can hospitals use instead?

The IV fluids in short supply are saline and Hartmann’s solution. They are provided by three approved Australian suppliers: Baxter Healthcare, B.Braun and Fresenius Kabi.

The government’s solution to this is to approve multiple overseas-registered alternative saline brands, which they are allowed to do under current legislation without it going through the normal Australian quality checks and approval process. They will have received approval in their country of manufacture.

The government is taking this approach because it may not be effective or safe to formulate medicines that are meant to be in saline into different IV fluids. And we don’t have sufficient capacity to manufacture saline IV fluids here in Australia.

The Australian Society of Hospital Pharmacists provides guidance to other health staff about what drugs have to go with which IV fluids in their Australian Injectable Drugs Handbook. If there is a shortage of saline or Hartmann’s solution, and shipments of other overseas brands have not arrived, this guidance can be used to select another appropriate IV fluid.

Why don’t we make it locally?

The current shortage of IV fluids is just another example of the problems Australia faces when it is almost completely reliant on its critical medicines from overseas manufacturers.

Fortunately, we have workarounds to address the current shortage. But Australia is likely to face ongoing shortages, not only for IV fluids but for any medicines that we rely on overseas manufacturers to produce. Shortages like this put Australian lives at risk.

In the past both myself, and others, have called for the federal government to develop or back the development of medicines manufacturing in Australia. This could involve manufacturing off-patent medicines with an emphasis on those medicines most used in Australia.

Not only would this create stable, high technology jobs in Australia, it would also contribute to our economy and make us less susceptible to future global drug supply problems.

Nial Wheate, Professor and Director Academic Excellence, Macquarie University and Shoohb Alassadi, Casual academic, pharmaceutical sciences, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

No, you’re not imagining it. People really are more likely to poo in the morning, shortly after breakfast. Researchers have actually studied this.

But why mornings? What if you tend to poo later in the day? And is it worth training yourself to be a morning pooper?

To understand what makes us poo when we do, we need to consider a range of factors including our body clock, gut muscles and what we have for breakfast.

Here’s what the science says.

So morning poos are real?

In a UK study from the early 1990s, researchers asked nearly 2,000 men and women in Bristol about their bowel habits.

The most common time to poo was in the early morning. The peak time was 7-8am for men and about an hour later for women. The researchers speculated that the earlier time for men was because they woke up earlier for work.

About a decade later, a Chinese study found a similar pattern. Some 77% of the almost 2,500 participants said they did a poo in the morning.

But why the morning?

There are a few reasons. The first involves our circadian rhythm – our 24-hour internal clock that helps regulate bodily processes, such as digestion.

For healthy people, our internal clock means the muscular contractions in our colon follow a distinct rhythm.

There’s minimal activity in the night. The deeper and more restful our sleep, the fewer of these muscle contractions we have. It’s one reason why we don’t tend to poo in our sleep.

But there’s increasing activity during the day. Contractions in our colon are most active in the morning after waking up and after any meal.

One particular type of colon contraction partly controlled by our internal clock are known as “mass movements”. These are powerful contractions that push poo down to the rectum to prepare for the poo to be expelled from the body, but don’t always result in a bowel movement. In healthy people, these contractions occur a few times a day. They are more frequent in the morning than in the evening, and after meals.

Breakfast is also a trigger for us to poo. When we eat and drink our stomach stretches, which triggers the “gastrocolic reflex”. This reflex stimulates the colon to forcefully contract and can lead you to push existing poo in the colon out of the body. We know the gastrocolic reflex is strongest in the morning. So that explains why breakfast can be such a powerful trigger for a bowel motion.

Then there’s our morning coffee. This is a very powerful stimulant of contractions in the sigmoid colon (the last part of the colon before the rectum) and of the rectum itself. This leads to a bowel motion.

How important are morning poos?

Large international surveys show the vast majority of people will poo between three times a day and three times a week.

This still leaves a lot of people who don’t have regular bowel habits, are regular but poo at different frequencies, or who don’t always poo in the morning.

So if you’re healthy, it’s much more important that your bowel habits are comfortable and regular for you. Bowel motions do not have to occur once a day in the morning.

Morning poos are also not a good thing for everyone. Some people with irritable bowel syndrome feel the urgent need to poo in the morning – often several times after getting up, during and after breakfast. This can be quite distressing. It appears this early-morning rush to poo is due to overstimulation of colon contractions in the morning.

Can you train yourself to be regular?

Yes, for example, to help treat constipation using the gastrocolic reflex. Children and elderly people with constipation can use the toilet immediately after eating breakfast to relieve symptoms. And for adults with constipation, drinking coffee regularly can help stimulate the gut, particularly in the morning.

A disturbed circadian rhythm can also lead to irregular bowel motions and people more likely to poo in the evenings. So better sleep habits can not only help people get a better night’s sleep, it can help them get into a more regular bowel routine.

Regular physical activity and avoiding sitting down a lot are also important in stimulating bowel movements, particularly in people with constipation.

We know stress can contribute to irregular bowel habits. So minimising stress and focusing on relaxation can help bowel habits become more regular.

Fibre from fruits and vegetables also helps make bowel motions more regular.

Finally, ensuring adequate hydration helps minimise the chance of developing constipation, and helps make bowel motions more regular.

Monitoring your bowel habits

Most of us consider pooing in the morning to be regular. But there’s a wide variation in normal so don’t be concerned if your poos don’t follow this pattern. It’s more important your poos are comfortable and regular for you.

If there’s a major change in the regularity of your bowel habits that’s concerning you, see your GP. The reason might be as simple as a change in diet or starting a new medication.

But sometimes this can signify an important change in the health of your gut. So your GP may need to arrange further investigations, which could include blood tests or imaging.

Vincent Ho, Associate Professor and clinical academic gastroenterologist, Western Sydney University

This article is republished from The Conversation under a Creative Commons license. Read the original article.