17 Medicine Cabinet Essentials by Jake

You’re likely familiar with the mountain of tablets and capsules, creams and lotions, syrups, drops, inhalers and other medications that dwell in your medicine cabinet. But what makes these ‘medicine cabinet essentials’, essential? What makes painkillers easy treatments for fever or toothache, and—while they won’t cure regret—how can they help you cope with a hangover? Antihistamines, indigestion treatments, and anti-diarrhoea tablets are also hallmarks of a wellstocked medicine cabinet, but how do they work? Here are a few such medications and their modes of action, which will offer some insight into the most popular medicine cabinet essentials.

Starting with the medicine cabinet powerhouses, NSAIDs include ibuprofen, aspirin, and naproxen, among many others. They are anti-inflammatories which work by inhibiting the activity of cyclooxygenase (COX) enzymes responsible for converting a compound called arachidonic acid (found naturally in the body) into a number of signalling molecules which play a “house-keeping” role in regulating many physiological processes, including causing inflammation (on the diagram, these molecules are shown as PGE2, TXA2, and PGI2)

Inflammation occurs due to a high amount of blood flow into areas of injury or infection, resulting in redness, warmth, and painful swelling as fluids leak into surrounding tissues.

Therefore, the therapeutic, pain-relieving effects of NSAIDs are attributed to the lack of these signalling molecules. Indeed, the ability to tackle headaches caused by inflammations make these useful hangover cures.

NSAIDs also prevent blood clotting by the same mechanism; one of these signalling molecules, called thromboxane (TXA2 on the diagram), promotes the adhesion of platelets (one of the key components involved in blood clotting). When COX enzymes are inhibited by NSAIDs, they are unable to synthesise thromboxane; thus, many NSAIDs have anti-coagulant properties,

The importance of NSAIDs is enormous. Aspirin and ibuprofen have earned a spot on the WHO Model List of Essential Medicines, among other medications considered to be the most safe and effective in meeting the most important needs of any health system.

Summer is almost universally something that people look forward to. For those with pollen allergies, however, summer usually means the start of the hay fever season. Allergies occur when the body reacts to a compound as if it were harmful, initiating an unnecessary immune response.

Pollen is just one allergy of many, but allergic reactions all work in a similar way; they involve the release of a huge amount of histamine.

Histamine is a compound responsible for many symptoms of an allergic reaction. They attract white blood cells to the area of perceived ‘infection’, and cause inflammation by triggering capillaries to widen and fluid to leak into surround tissue, leading to swelling, tenderness, and redness.

Treating allergic symptoms, therefore, becomes a case of simply blocking the activity of histamine. Antihistamines counteract the downstream effects of histamine by blocking H (histamine) receptors, so that any histamine released cannot reach its target area, reducing the severity of allergic symptoms.

Antihistamines are not a cure to allergies, but they are useful in treating them. It is worth noting, however, that the development and use of antihistamines is changing.

First generation antihistamines have a prominent sedative effect, and for this reasons they are now are far less favoured as a means of treating allergies. Recently, they have been superseded by a newer, second generation of antihistamines which are designed to be as effective as before, but less sedating.

Whether or not caffeine qualifies as a ‘medicine cabinet essential’ may depend on who you ask, but considering that 90% of adults worldwide consume caffeine in some form, it is worth discussing here.

First, consider a molecule called adenosine. It is one of the fundamental building blocks of DNA and RNA— essential for all life that we know of—and regulates a huge array of physiological processes. Adenosine helps in cellular energy transfer by forming molecules like adenosine triphosphate (ATP) and adenosine diphosphate (ADP). It also plays a role in various reaction pathways in the brain by forming signalling molecules like cyclic adenosine monophosphate (cAMP).

It is adenosine’s role in promoting sleep, however, that is most affected by caffeine. In the brain, adenosine is an inhibitory neurotransmitter which suppresses nerve cell activity and causes drowsiness. Levels of adenosine gradually rise when we are awake such that we feel sleepy toward the end of the day before it is broken down over night and the cycle repeats.

Caffeine is similar in chemical structure to adenosine and is therefore able to occupy the same receptors in the synapse that adenosine can. However, while adenosine activates these receptors (making it an agonist), caffeine does not (making it an antagonist).

Thus, when caffeine is blocking these receptors, adenosine is temporarily unable to bind to and activate them, leading to feelings of alertness.