Cannabidiol (CBD) to 27 Patients (Aged 2 Years - 19 Years) With Drug Resistant Epilepsy

This multi-center study will consist of two parts: Part A and Part B. Part A will investigate
the dose-ranging pharmacokinetics and tolerability of GWP42003-P.

Part B is a 1:1 randomized, placebo-controlled 60 day comparison of GWP42003-P against
placebo, at the dose which has been identified by Part A as the maximum tolerated dose. Part
B will investigate the efficacy and safety of GWP42003-P.

Following completion of Part B, all patients will be invited to continue to receive
GWP42003-P in an open label extension study (which is separate to this protocol).

Part A Following establishment of initial eligibility and baseline measurements, patients
will enter Part A at Visit 1 and will begin the two month baseline observation period.
Patients will record their number of convulsive seizures, and of other seizures, using an
IVRS telephone diary system (recorded twice each day). Each call will take approximately five
minutes to complete. Patients will return to the clinic at Visit 2 and the investigator will
assess the patient's daily number of convulsive seizures from the patient's IVRS data.
Patients who have experienced at least four convulsive seizures (tonic-clonic seizures and/or
drop attacks) per month for each of the previous two months) and who meet all of the other
inclusion/ exclusion criteria will be eligible to continue in the study. Patients will be
asked for information regarding AEs, concomitant medications and/or changes to their
medication.

Eligible patients will enter into the pharmacokinetics part of the study at Visit 2 where
blood samples will be taken using a sparse sampling strategy to minimize the blood volumes
required for analysis of the plasma concentration/time curve for concomitant AEDs and routine
safety bloods. This is conducted prior to the administration of Study medication at Dose
Level 1.

In each dose level, patients will be randomly assigned so that eight patients receive
GWP42003-P and two patients receive placebo in each group. Patients will receive their study
medication each day for the seven day exposure period. During this part of the study,
patients will continue to record their daily number of convulsive seizures and of other
seizures, using an IVRS telephone diary system.

At Day 7 (Visit 3), blood will be taken for analysis of both the plasma concentration/time
curve of GWP42003-P and its major metabolite, concomitant anti-epileptic medications and for
routine safety purposes. At the end of the dosing period in Part A of the study patients will
continue on placebo until they are ready to enter Part B of the study.

Dose Level 2 will follow the same set of procedures as Dose Level 1, but dosing will not
start until an evaluation of the clinical and pharmacokinetic results from Dose Group 1 has
been completed. Subsequently Dose Groups 3 and 4 will be subject to the same procedures.

When Dose Group 4 has completed the seven day Dosing Period, and subject to assessment of
clinical safety and pharmacokinetics, patients will then be invited to continue into Part B,
which is the double blind, randomized, placebo-controlled phase to investigate the efficacy
and safety of GWP42003-P. There will be a washout period of at least two weeks between the
last dosing day in Part A and randomization in Part B.

Part B Patients, from any of the dosing groups, who have completed will be invited to
participate into Part B which is a 1:1 randomized, placebo-controlled 60 day comparison of
GWP42003-P against placebo. They will receive the dose which was identified by Part A as the
maximum tolerated dose. Part B will investigate the efficacy and safety of GWP42003-P.

During Part B, patients will continue to record their number of convulsive seizures and other
seizures, using an IVRS telephone diary system (recorded twice each day). Assessments will
also be made of cognitive function, nocturnal sleep quality and daytime sleepiness.

Note: Eligible patients who have not previously participated in Part A, and who wish to
participate in Part B will begin the two month baseline observation period to establish a
baseline. Patients will follow the same procedures as outlined in Visit 1 (of Part A).
Patients will record their number of convulsive seizures (and of other seizures), using an
IVRS telephone diary system (recorded twice each day).

Part A: The primary endpoint is the safety and tolerability profile of single and multiple
ascending doses of GWP42003-P compared with placebo.

The variables for analysis will be the difference in incidence, type and severity of AEs,
vital signs, ECG, laboratory, and physical examination parameters of GWP42003-P compared with
placebo.

Part B: The primary endpoint is the number of patients experiencing at least a 50% reduction
in the number of convulsive seizures (from baseline) on active treatment compared with
placebo.

Part A: Pharmacokinetic:

1. GWP42003-P: The plasma concentration/time curve will be described following multiple
doses of GWP42003-P, with the aim being to define

- Cmax

- tmax

- AUC0-∞, AUC0-t

- t½ The analytes for the pharmacokinetic analysis will be CBD and its major human
metabolite 7-OH-CBD.

2. Concomitant AEDs: The plasma concentration/time curve for concomitant AEDs will be
described pre-treatment, and then after seven days of treatment with GWP42003-P, using a
sparse sampling strategy. As far as possible, the plasma concentration/time relationship
pre-treatment will be compared with the results following treatment with GWP42003-P.

Part B: Efficacy:

1. Number and type of non-convulsive seizures

2. Cognitive function

3. Sleep quality

4. Caregiver Global Impression of Change

Inclusion Criteria:Patients meeting the following criteria will be considered eligible for
this study:

- Documentation of a diagnosis of drug resistant epilepsy as evidenced by failure to
control siezures despite appropriate trial of four or more Anti-Epileptic Drugs at
therapeutic doses. Documentation must include the diagnosis of epilepsy type or
epilepsy syndrome (if possible), as well as the underlying case, when known.

- Between 1-3 baseline anti-epileptic drugs at stable doses for a minimum of 4 weeks
prior to enrollment. Vagus nerve stimulator, ketogenic diet and modified Atkins diet
do not count toward this limit.

- Vagus nerve stimulator must be on stable settings for a minimum of 3 months.

- Written informed consent obtained from the patient or the patient's legal
representative must be obtained prior to beginning treatment.

Exclusion Criteria:Exclusion: The patient may not enter the study if ANY of the following
apply:

• Treatment with any artisanal preparation containing or possible containing CBD during the
month before initiation of the study drug.