Annunziata Lombardi
Annunziata Lombardi
VP Scientific Affairs
Share this article

Pharmaceutical forms and mode of intake (part 3 of 4)


Pharmacists play a crucial role in preparing medical cannabis in accordance with established regulations and guidelines. By following the Norms of Good Preparation (NBP), pharmacists create magistral preparations of cannabis, ensuring the distribution of the active substance in the appropriate dose and medication form, as prescribed by doctors. The administration of medical cannabis involves oral intake through decoctions or quantified oil extracts, as well as inhalation using specialized vaporizers. 

Medical cannabis can be taken orally through decoctions or extracts in quantified oil or through inhalation using a specialized vaporizer. Different forms of administration can alter the chemical profile of the cannabis plant, with heating playing a crucial role in converting acidic cannabinoids into their active form. Recent research challenges the belief that cannabinoid acids are inactive, highlighting their potential medicinal properties. It is important to heat the cannabis properly and follow strict procedures to avoid the formation of degradation products and ensure the retention of volatile components like terpenes. 

This article explores the preparation and administration of medical cannabis in compliance with regulatory norms and guidelines while also emphasizing the importance of adhering to strict procedures to ensure the quality and quantity of active ingredients. 

The pharmacist prepares in the drugstore, in compliance with the Norms of Good Preparation (NBP), magistral preparations of cannabis involving the distribution of the active substance in dose and form of medication, according to the dosage and mode of intake indicated by the prescribing doctor, in accordance with the guidelines provided by the Ministry of Health. The posology for the medical use of cannabis, provides the oral intake of the decoction or extract in quantified oil and the administration by inhalation, through the use of a specific vaporizer.   

Depending on the form of administration, different changes to the original chemical profile of the plant can be found. For instance, one factor common to most forms of administration is the timing of heating, which is essential for the conversion of the acidic cannabinoids into their pharmacologically active form. Cannabinoids, contrary to popular belief, are not actually present in fresh cannabis plants. The reason is that the plant produces all of its cannabinoids in a slightly different form, known as cannabinoid acids or cannabinoidiacids. When sufficient heat is applied, cannabinoid acids are quickly converted into their ‘neutral’ counterparts through a process called decarboxylation. Thus, when cannabis is burned for smoking or boiled for decoction, the THC-acid transforms into its neutral THC-form, CBD-acid becomes CBD, and so on for all the other cannabinoids. Decarboxylation also occurs spontaneously, as a result of storage and exposure to light or room temperature, but at a much slower rate.    

For a long time, scientists considered cannabinoid acids an ‘inactive’ form of cannabinoids, because they do not cause the sensation of a high and do not bind to cannabinoid receptors. Recent research shows, however, that cannabinoid acids may also have important medicinal properties. For example, CBD-acid has potent antimicrobial activity and shows promising anti-inflammatory qualities, while THC-acid has been shown to have a powerful effect on the human immune system. The overheating can lead to the formation of degradation products such as cannabinol (CBN) and Delta-8-THC, and volatile components such as terpenes can easily be dispersed by evaporation, e.g., during boiling of the decoction, or concentrating an extract by evaporation of the solvent so it is essential to comply with strict procedures.

In the case of oral administration by decoction, the doctor will instruct the patient on how and when to prepare the decoction, the amount of cannabis and water to be used, and the number of doses per day according to the manufacturer’s instructions.  

When taking the decoction, it is the patient who is responsible for the preparation of the medicine at home, so in order to obtain a standardized medicine, it is necessary for the patient to scrupulously follow the instructions provided.  If oral administration does not produce the desired pharmacological effects, or when the doctor considers it appropriate, the inhalation route of administration may be used by means of an inhaler vaporizer with filtered hot air (CE-marked medical device). Common aerosol devices are not suitable. Even in the case of inhalation administration, the doctor informs the patient of the quantities to be used, the intervals between inhalations and the number of inhalations to be made during the day and the inhalation temperature. As with the decoction, also for inhalation intake, it is necessary for the patient to follow the doctor’s scrupulous instructions because the parameters used in the inhalation process can influence the quality and quantity of the active ingredients taken in. 

Cannabis concentrate extracts: history and science 

The galenic preparation of concentrated medical cannabis extracts in pharmacies began with the publication of one of the first studies on the subject. In early 2013, a study entitled: “Cannabis oil: chemical evaluation of an upcoming cannabis-based medicine,” was published by Dr. Biologist Luigi Romano and Dr. PhD Arno Hazekamp.  In this first qualitative study, a crucial point in the preparation is addressed: the decarboxylation (e.g., the heating process used to convert the acid cannabinoids, THCA or CBDA into neutral cannabinoids, THC or CBD). The authors conclude that in order to best preserve the plant phytocomplex and, in particular, the terpenic component, the process of heating the plant material should be avoided. This process in fact favors the decarboxylation of the main cannabinoids to the detriment of the more volatile component consisting of terpenes (e.g., mono- and sequi- terpenes).

The second part of the study highlights which active compounds (e.g. cannabinoids and terpenes) are extracted with certain solvents and which of these solvents should be avoided as they leave residues in the final extract. This study concludes by specifically selecting two solvents suitable for human consumption and of which pharmaceutical grade lines exist: ethanol, or ethyl alcohol, and olive oil. Doctors and pharmacists have respectively begun prescribing and formulating galenic preparations based on cannabis extracts, referring to the aforementioned study.

Based on this article, in the following years, other authors published several variants of the well-known ‘Roman – Hazekamp method’. Studies such as those by Citti et al, 2016; Pacifici et al, 2017; Calvi et al, 2018, SIFAP (Società Italiana Farmacisti Preparatori) and others have shown that ethanol and olive oil are the most suitable choice as extraction solvents and that, by making modifications to the process, the end result improves both in terms of quantity and quality.   

All the studies mentioned are evidence of a very broad scientific interest in the galenic preparation of medical cannabis extracts. In particular, the careful analyses of the mentioned studies address to the possibility of obtaining a standardized extract in cannabinoid concentration and ratio that doctors can prescribe with precise dosages and posologies. Such a preparation, moreover, is preferred by patients who can thus take their therapy simply by swallowing drops or capsules that are exactly dosed. 


[1, 4] Romano L. and Hazekamp A. 2013. Cannabis oil: chemical evaluation of an upcoming cannabisbased medicine. Cannabinoids, 2013, 1(1); 1-11. 

[2] Perrotin-Brunel, H.; Buijs, W.; van Spronsen, J.; van Roosmalen, M.J.E.; Peters, C.J.; Verpoorte, R.; Witkamp, G. Decarboxylation of Δ9-tetrahydrocannabinol: Kinetics and molecular modeling. J Mol Struct, 2011, 987(1-3), 67-73. 

[3] Wang, M.; Wang, Y.; Avula, B.; Radwan, M.M.; Wanas, A.S.; van Antwerp, J.; Parcher, J. F.; ElSohly, M.A.; Khan, I.A. Decarboxylation study of acidic cannabinoids: a novel approach using ultra-high-performance supercritical fluid chromatography/photodiode array-mass spectrometry. Cannabis Cannabinoid Res, 2016, 1(1), 262-271. 

[5] Citti C., Ciccarella G., Braghiroli D., Parenti C., Vandelli M. A., Cannazza G. 2016. Medicinal cannabis: Principal cannabinoids concentration and their stability evaluated by a high performance liquid chromatography coupled to diode array and quadrupole time of flight mass spectrometry method. J Pharm Biomed Anal. 2016 Sep 5;128:201-209. 

[6] Pacifici R., Marchei E., Salvatore F., Guandalini L., Busardò F. P., Pichini S. 2017. Evaluation of cannabinoids concentration and stability in standardized preparations of cannabis tea and cannabis oil by ultrahigh performance liquid chromatography tandem mass spectrometry. Clin Chem Lab Med. 2017 Aug 28;55(10):1555-1563. 

[7] Calvi L., Pentimalli D., Panseri S., Giupponi L., Gelmini F., Beretta G., Vitali D., Bruno M., Zilio E., Pavlovic R., Giorgi A. 2018. Comprehensive quality evaluation of medical Cannabis sativa L. inflorescence and macerated oils based on HS-SPME coupled to GC-MS and LC-HRMS (q-exactive orbitrap®) approach. Journal of Pharmaceutical and Biomedical Analysis Volume 150, 20 February 2018, Pages 208-219. 

[8, 10] Carcieri C., Tomasello C., Simiele M., De Nicolò A., Avateneo V., Canzoneri L., Cusato J., Di Pierri G., D’Avolio A. 2017. Cannabinoids concentration variability in cannabis olive oil galenic preparations. J Pharm Pharmacol. 2018 Jan;70(1):143-149 

[9, 11] Casiraghi A., Roda G., Casagni E., Cristina C., Musazzi U. M., Franzè S., Rocco P., Giuliani C., Fico G., Minghetti P., Gambaro V. 2018: Extraction method and analysis of cannabinoids in Cannabis olive oil preparations. Planta Medica, vol. 84 (4), pp. 242-249. 

[12] Patient information of the Dutch Office of Medicinal Cannabis at 

[13,14] DECRETO 9 novembre 2015 Funzioni di Organismo statale per la cannabis previsto dagli articoli 23 e 28 della convenzione unica sugli stupefacenti del 1961, come modificata nel 1972. (15A08888) (GU n.279 del 30-11-2015). 

[15,16,17] An introduction to Medicinal Cannabis Dr. Arno Hazekamp. 

[17,18] Ministero della Salute DGDSFC/ I.6.b /2016/19 Documento recante raccomandazioni ai medici prescrittori di Cannabis FM-2 prodotta dallo Stabilimento Chimico Farmaceutico Militare di Firenze secondo le normative dell’UE in materia di sostanze attive, certificata GMP secondo le Good manufacturing practices dell’UE. 

Related Publications

Discover more about this topic and get the latest updates about the cannabis industry.