Medical cannabis affects each patient differently, with some patients being sensitive to low doses while others having greater tolerance. Due to this we recommend patients begin with a low dose. The TGA report suggests a starting dose of 2.5mg of THC. The maximum studied daily dose, based on TGA assessed data, is 97.5mg given in four divided doses q.i.d. Should patients experience negative side effects of medical cannabis, they should cease dosing until side effects abate and resume dosing at a known lower, tolerated dose. Overall effect of medical cannabis should be assessed at the end of the first month of treatment.
Medical cannabis can be administered via numerous routes; the most common being inhaled, ingested or placed under the tongue (sublingual). Ingested and sublingual administrations allow for flexibility in time to onset and the duration of the effect.
Sublingual administration allows for a rapid onset of effect, with peak plasma concentrations typically achieved within 30 minutes. However, sublingual dosing can also be accompanied by a varied biphasic plasma concentration depending on the amount of drug that is ingested orally following sublingual dosing.
Orally ingested cannabis can take up to 2 hours for patients to feel an effect with times being variable from patient to patient. Caution should be taken as the effects of orally administered cannabis oil are slow to present and under no circumstance should patients re-administer dosing within the two hour period. Following oral administration, peak plasma concentrations are thought to be achieved within 2 hours.
Medical cannabis has the potential to be abused and to produce psychological dependence. It has complex effects on the central nervous system. Its effects on the mental state (i.e., “inner mental life”) are similar to those of cannabis. Subjects given medical cannabis may experience changes in mood (e.g., euphoria, detachment, depression, anxiety, panic, paranoia), decrements in cognitive performance and memory, a decreased ability to control drives and impulses, and alterations in the experience of reality (e.g., distortions in the perception of objects and the sense of time, hallucinations).
These phenomena appear to be more common when larger doses, specifically THC, are administered. Tolerance to these effects develops rapidly and is readily reversible. Experience with cannabis suggests that chronic use of cannabinoids may be associated with a variety of untoward effects on motivation, cognition, judgment, as well as other mental status changes. Whether these phenomena reflect the underlying character of individuals chronically abusing cannabis or are a result of the use of cannabis is not known.
The simultaneous use of medical cannabis and alcohol or barbiturates may produce additive depressive effects on central nervous system function. Medical Cannabis has several systemic actions; most prominent are dry mouth and hypotension.
Signs and symptoms
Signs and symptoms of overdosage are an extension of the psychotomimetic and physiologic effects of medical cannabis.
To obtain up-to-date information about the treatment of overdose, a good resource is your certified Regional Poison Control Center. Medical cannabis should not be taken with alcohol, sedatives, hypnotics, or other psychoactive substances because these substances can potentiate the central nervous system effects of medical cannabis.
Overdosage may be considered to have occurred, even at prescribed dosages, if disturbing psychiatric symptoms are present. In these cases, the patient should be observed in a quiet encymraonment and supportive measures, including reassurance, should be used. Subsequent doses should be withheld until patients have returned to their baseline mental status; routine dosing may then be resumed if clinically indicated. In such instances, a lower initiating dose is suggested.