Identify a chemovar of Cannabis sativa for treatment of chronic pain. Justify your choice.

There are many different causes of chronic pain ranging from joint pain and inflammation to pain caused by nerve damage, triggered by multiple sclerosis or central pain such as fibromyalgia.

The cannabinoids CBD and THC have been shown to be effective in fighting pain and inflammation. CBD is believed to relieve pain signals as they make their way to the brain, while THC can regulate pain at both the brain and musculoskeletal level. 

A sativa cultivar that has a good balance of THC and CBD is optimal as it can reduce inflammation and positively impact many different receptor systems in the body.

Harlequin is an excellent choice for chronic pain for people who want to feel relaxed yet remain clear-headed. It is a sativa dominant strain with less than 10% THC and close to 1:1 THC and CBD balance.

It’s high levels of CBD make it really effective at treating pain and anxiety and also counteracts the psychoactive effects of the THC while amplifying it’s pain relief properties. 

It also has high levels of the terpenes Myrcene and Pinene. Myrcene is believed to promote calming effects and be a muscle relaxant. Pinene is one of the most common terpenes in the world and is said to also help reduce anxiety, inflammation and pain.

Describe a method of cultivation for your chemovar of choice and discuss factors that can affect growth and yield performance.

Harlequin produces a heavy yield and is a moderately easy plant to grow. It’s flowering cycle is 8 weeks and should be harvested early as CBD levels degrade more easily than THC.

Cultivating the plants in a controlled environment will also improve the production of CBD, therefore growing in a greenhouse is optimal. Using a greenhouse allows you to avoid some of the complexities required to set-up an indoor grow room. Additionally, it’s often considered to be superior to growing outdoors as it’s more secure, more consistent and predictable. It combines the best parts of the natural elements like natural light and warmth with protection against the worst parts; such as bad weather, cold conditions, pests and pathogens.

Cannabis plants love water (but not too much), warmth and light, with the ideal conditions being a sub-tropical temperature of around 23-26°C. This can easily be achieved in a greenhouse but due to the heat rising and being trapped, there will be a hotter zone higher up. Therefore, it’s important to keep the plants from growing too high towards the top of the structure.
It’s also important to have the ability to heat or cool the environment throughout the day and the seasons of the year.

Finding a good mother plant to clone is often considered preferable to growing from seeds. It saves time and eliminates the necessity to weed out male plants. The cuttings will be exact genetic copies of the mother plant and, as they will be growing in the same conditions, they should all reach the same size and height with known quantities of buds at harvest time. 

Growing this way does require extra space in the greenhouse to maintain the mother plants. As they age they will become more susceptible to diseases and pests. If the mother becomes weaker with age or the nutrients in the soil are depleted, this will affect the quality of the clones produced. The cloned plants can be grown in the ground or in large pots using high quality, organic soil. Using containers adds the advantage of being able to move them around if necessary.

The nutrients and environment needed for an optimal harvest vary throughout the plant's life cycle. The three foundational macronutrients plants need are nitrogen (N), potassium (K) and phosphorus (P). Micronutrients are also needed but in smaller quantities. They include calcium, magnesium, copper, iron, chlorine and zinc. Additionally plants derive carbon, hydrogen and oxygen from the air and water. 

The plants need varying amounts of these nutrients at the different growth stages. In the vegetative stage they require high inputs of nitrogen but when flowering they require more phosphorus and potassium. Growing in a greenhouse means the plants will receive plenty of natural sunlight, but during spring and autumn it may be necessary to use some artificial lighting to achieve the best yield. If choosing to grow in winter then they will definitely be required.

Light cycles of between 18–24 hours are used during the vegetative phase of the grow cycle. When growing outdoors the cycle of the sun causes this shift to happen naturally over time. Some greenhouse cultivators choose to use artificial lighting after the sun has set and before it has risen. The shift to a light cycle of 12-12 is what causes photoperiod strains to enter the flowering phase of the grow cycle. 11 hours of uninterrupted darkness signals the plant to flower. 

If supplementing with artificial light, it is suggested to use metal halide or fluorescent bulbs during the vegetative growth stage and HPS grow lights for the flowering phase.

The greenhouse method is superior to growing completely indoors if you are wanting to produce buds with a unique terroir. This means the natural environment, such as sunlight, breeze, insects and soil can all influence the characteristics of the end product. If grown completely indoors, the plants do not get affected by any of these elements and could therefore have been grown anywhere in the world.

The canopy diameter is the best predictor of yield. If you have tall and short plants then the shorter ones will not receive as much light. By keeping them all around the same height and utilising the space to ensure decent airflow, a larger yield will be easier to obtain.

A good way of doing this is using the Low Stress Training (LST) technique. It’s the practice of gently bending stems and tying them in place to change the shape of the plant. This is done to create multiple bud sites, even out the canopy, and overall help you use light more efficiently. It also encourages the circulation of the plant hormone, auxin, which dictates the plant's growth. It’s most highly concentrated at the top of the plant so when using LST the auxin is more evenly distributed in the plant, rather than just the normal focus of up through the main stalk. 

When harvesting the yield, the highest biomass will be achieved at 8-9 weeks but for higher THC levels it is best to wait until 9-11 weeks. For Harlequin, it is important to maximise the CBD levels as they will degrade over time, therefore harvesting at the 8-9 week stage is preferable.

As harvest time approaches, the resin glands or trichomes of the flowers are maturing. The three stages of development present in either clear, milky or amber resin. Harvesting when it’s clear is a little early as the potency will be lower than when it reaches the milky tone.

Not all trichomes change at exactly the same time so there will be a nice mix of clear, milky and amber resin. This means the cannabinoids are in different stages of their chemical maturity and also include all the good terpenes and flavonoids. Patients often prefer this full spectrum mixture, referring to the benefits as the entourage effect.

Investing in IoT technology to create a smart greenhouse is a great idea. Through the use of sensors and collation of data, the climate can be modulated, irrigation automated and humidity, CO2, nutrient levels, soil moisture and leaf temperature can all be carefully monitored and adjusted with the tap of a button.

Harvesting and drying are critical steps to get right, if left too late and not dried well the entire yield can be lost. Hang drying, with plenty of air circulating, for 10-14 days at 15-21°C and 50% relative humidity is a common method.

Knowing when it is properly dry can be determined using a water activity meter. Moisture content is performed on the flower and is a measure of the total amount of moisture in the material. It’s measured by using a moisture balance instrument method and involves measuring the weight of water loss before and after drying of a sample. Results are reported in Aw and ranges from 0 to 1. Pure water has an Aw of 1.0. The higher the value in your product, the more potential for microbial growth. 

Pulmonary delivery (smoking) is considered the most popular method to take cannabis. Discuss an alternative delivery route for cannabinoids and discuss its advantages and disadvantages. 

Smoking and eating cannabis are the two most common methods that people tend to choose, whether it’s for recreational or medicinal purposes. However, depending on the condition, many patients find taking it sublingually to be a superior delivery method.

Sublingual dosing means that the medicine being administered diffuses into the blood through the vessel-rich tissue under the tongue. It then drains into the sublingual vein and the lingual and jugular veins that lead directly into the circulatory system. Many drugs and vitamins use this sublingual method for quick absorption into the bloodstream.

Administering a cannabis oil or tincture in this way ensures that the cannabinoids immediately enter the bloodstream and therefore, provide fast-acting therapeutic effects. It can take from 30 seconds to two minutes for this application to take effect. This is great for patients with acute pain who need to get relief fast day or night.

Using this method is often considered a better approach for treating pain than medicating with an edible. With ingestion, the medicine must go through the stomach, the intestines and the liver before entering the bloodstream. This means it can take up to an hour or more to act, and also has reduced bioavailability of cannabinoids after they have been processed by the liver. Ingestion has more of a ‘time release’ effect that can be longer lasting. Therefore it can be good for secondary use to prolong pain relief and aid sleep throughout the night. 

Many people also prefer sublingual dosing to smoking cannabis. It is considered a safer choice as it doesn’t require inhalation of tar or cause throat irritation. It is definitely recommended for patients that suffer from respiratory issues plus it is a far less conspicuous way to treat pain in public.

Tinctures are concentrated extracts so depending on the THC level of the strain, a few drops of a sublingual tincture could contain more THC than a whole joint.

Bioavailability refers to the percentage of a dose absorbed by the body in comparison to an injected dose, which is considered 100% bioavailable.

A 2005 study, “Pharmacokinetics of cannabinoids'', found smoked THC to have about 30% average bioavailability. It also revealed “With a 3.55% THC cigarette, a peak plasma level of 152±86.3ng/ml occurred approximately 10 minutes after inhalation”.

Some sources claim that the bioavailability from using a sublingual application is up to 75% for THC and 25% for CBD. They suggest it is the most reliable absorption method producing the same effect each time and eliminating the unpredictability of methods such as smoking and ingesting products. 

With regards to extraction of cannabinoids and terpenes, discuss the advantages and disadvantages of solvent extraction. 

Cannabis extracts are a form of concentrate like an essential oil, often achieved using solvents to produce a higher amount of potency through concentrating the cannabinoids and terpenes, and a lesser amount of plant matter. These solvents include ethanol, butane, propane, and CO2, among others.

Ethanol is pure alcohol and considered the cleanest solvent to use for extraction, in terms of having little risk of toxicity for the consumer. It forms bonds with both water-soluble and fat-soluble plant compounds making it a good choice for people wanting a full-spectrum extract.

Butane Hash Oil (BHO) is the name given to every concentrate that uses Butane as the solvent for extraction. Like ethanol, when used properly it also produces a clean and safe product. Butane has the ability to extract highly desirable compounds from cannabis without co-extracting undesirable molecules such as chlorophyll and plant metabolites. 

Isopropyl alcohol is also an option and often used by people making oil at home. It has more toxic substances in it than butane and ethanol so isn’t recommended to be ingested.

All of these solvents are highly flammable so if used by an amateur, the risks involve inhalation of the solvent or producing an explosion.

The purest form of extraction is Supercritical CO2 leaving behind no residual traces of solvent and it is not explosive. It is the method most favoured by professional labs as it requires a big investment in expensive equipment.

One disadvantage of CO2 extraction is that it fails to extract the beneficial phytochemicals present in cannabis resin. Sometimes ethanol is used during the process to capture the lost terpenes. Although I have also read that the temperature pressure can be tuned to favour the extraction of certain cannabinoids and terpenes. 

Describe an extraction method that can capture the whole spectrum of cannabinoids and terpenes from cannabis. 

Full-spectrum extracts maintain the integrity of the original essence of the plant, including cannabinoids, terpenes, flavonoids, proteins, phenols, sterols and esters. They provide the flavour and aroma of the live plant and consequently the associated benefits of the entourage effect. It’s tricky to find an extraction technique that keeps all the desired compounds and removes the unnecessary ones, such as wax, fats and lipids.

Live resin is a form of hydrocarbon extract, meaning it is made with the solvents butane (BHO) or propane, or both together.
Live resin concentrates are made using fresh buds that have been frozen to a subcritical temperature immediately after harvest and during the extraction process.

Freezing halts the metabolic process and degradation of the terpenes that typically occur from drying and curing processes. After freezing for 24-36 hours then the extraction process should be initiated.

Using a closed loop extraction system, chilled butane is flushed through the solvent tank into the material column, saturating the raw material. As it passes through the cannabis, it extracts valuable cannabinoids and terpenes into a viscous substance that eventually dries. Closed loop systems, as well as being very safe, have advanced processes for isolating excess solvents and purging them with a vacuum system.

Freshly frozen cannabis causes some complications with hydrocarbon extractions because it contains significantly more water than dried flowers. Therefore, the temperature of the live resin extraction process is regulated to ensure no residual solvents remain. It has been found that extremely low temperatures of -20 to -50°F provide cold enough conditions to successfully keep excess plant water and butane from mixing in the live resin extraction process. Cold extraction temperatures also limit the solubility of lipids in the hydrocarbon, yielding a more potent extract.

Live resin comes in a variety of different consistencies and textures and is usually consumed by dabbing or vaping. The resin is then placed into containers where it is left to separate for two to three weeks. During that time cannabinoid crystals start to form on the bottom of the container as the solids separate from the terpenes, forming a thick, sticky liquid layer on top.


Compare and contrast the mechanism, advantages and disadvantages of quantifying cannabinoids with chromatography and near infrared techniques. 

There are several techniques that can be used to test the potency of cannabis by identification and measurements of cannabinoids and terpenes.

The most well-known are gas chromatography (GC), high-pressure liquid chromatography (HPLC), and near-infrared spectroscopy (NIR).

A rapid optical way of finding composition in the material is near infrared reflectance spectroscopy (NIR). This wavelength range is about 770 to 2500 nanometers beyond what is visible by the human eye, of which the range is between 400 - 700 nanometers.

This method is used in agriculture, food and chemical industries and is now widely used in testing cannabis. A sample is placed in a light path and the reflected light is analysed to show what’s present.

Using a Cannalyzer gadget, the infrared light source beams down on the raw material, the light is then emitted from the surface. It is the colour of the data that is collected and analysed by the spectrometers. This data shows how much light is being absorbed. It then has to be related to chemistry models for comparison to identify THC, THCA, CBD and CBDA.

The NIR technique is fast and a lot cheaper than GC and HPLC but it cannot identify terpenes, pesticides and solvent residue which is also important data to report on. It can be used in conjunction with other techniques to provide a more comprehensive data set.

Chromatography is the technology most used to define composition. It's the technique for the separation of a mixture by passing it in a solution through a medium in which the components move at different rates.

It was originally done on absorbent paper and can be illustrated by the behaviour of black ink on blotting paper, which is known as the stationary phase. The black ink is made up of many colours that move at different rates in the watery medium, which is called the mobile phase. This occurs as some colours are more bound to the paper, while others prefer being in the liquid solution.

Cannabinoids are not coloured although it is possible to see some coloured data from them by using a diazonium salt Fast Blue. However the coloured spots diffuse and spread quickly, therefore the data is not clear enough. This method also fails to indicate terpene levels.

This diffusion problem makes the technique very uncontrolled and inaccurate. This can be overcome by a technique called Thin Layer Chromatography (TLC). This typically uses a silica gel as the stationary phase which is spread and dried on a sheet of glass. The thinness of the layer minimises diffusion. Cellulose and aluminium oxide can also be used.

Gas chromatography (GC) and high pressure liquid chromatography (HPLC) are two more sophisticated methods that conceptually use the same stationary and mobile phases. Both are based on tubes that analyse the chemicals as they are passed through at different speeds. The wall of the column has different affinities for each of the injected material to be tested - for example THC, CBD and CBN.

The mobile phase is carrier gas, often helium, it passes through the column and separates out the material as they pass through at different speeds. The column is housed in an oven and the temperature is increased from low to high depending on the chemicals being tested. The cannabinoids get separated out far more precisely than in the TLC example.

Detection of the compounds is done using flame ionization detection or mass spectral detection. Flame ionisation is cheap and sensitive but cannot identify a peak. To resolve that issue authentic standards can be purchased so a test run can be produced using the same retention time.

Mass spectral detection provides much more information about unknown peaks but this method is very expensive. As an unknown peak emerges, it is electronically zapped and breaks compounds apart. From these parts, relatively accurate assumptions can be made based on existing library patterns of what the chemical is.

GC is also the ideal way to analyse terpenes as they are volatile and stable to heat. Because GC requires high temperatures, a major disadvantage of the method is that it changes the form of the cannabinoids via decarboxylation. As all THCA and CBDA will change to THC and CBD.

This can be resolved using HPLC. Like the previous examples it too has stationary and mobile phases. The process is done at room temperature so there is no heating of the cannabinoids and they remain in their original states.

The analytes permeate the porous outer layer of the stationary phase that is retained in a thin cylinder. High pressure is used to push through the mobile phase along with the cannabinoids through the cylinder before they have time to spread by diffusion.

Unlike GC, flame ionisation is not an option as it heats the chemicals. Therefore mass spectrometry is a good choice for detection.

Alternatively an ultraviolet light absorption method can be used. Cannabinoids have what’s known as a benzene ring structure, which absorb UV light. Different wavelengths will absorb slightly differently for each cannabinoid.

In summary, HPLC is superior method over GC and NIR, however cost can be prohibitive and a combination of GC and NIR could be used to identify and analyse all the data necessary.

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