Metvix - Pharmaceutical Information, Clinical Trials, Detailed Pharmacology, Toxicology.
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Metvix - Scientific Information

Manufacture: Galderma Laboratories
Country: Canada
Condition: Actinic Keratosis, Basal Cell Carcinoma, Skin Cancer
Class: Antibiotics/antineoplastics, Antineoplastics
Form: Cream
Ingredients: methyl aminolevulinate hydrochloride, glyceryl monostearate, cetostearyl alcohol, polyoxyl stearate, cholesterol, oleyl alcohol, glycerol, white soft paraffin, isopropyl myristate, arachis (peanut) oil, refined almond oil, edetate disodium, methylparaben, propylparaben, purified water.

Pharmaceutical Information

Drug Substance

Proper name: methyl aminolevulinate hydrochloride
Chemical names: methyl 5–aminolevulinate hydrochloride, 5–aminolevulinic acid methyl ester hydrochloride, 5–amino–4–oxopentanoic acid methyl ester hydrochloride, methyl 5–amino –4–oxopentanoate hydrochloride, methyl 5–amino –4–oxovaleroate hydrochloride, 5–amino–4–oxovaleric acid methyl ester hydrochloride
Molecular formula: C6H11NO3•HCl
Molecular mass: 181.62
Structural formula:
Physicochemical properties: Methyl aminolevulinate hydrochloride is a white to slightly yellow powder that is freely soluble in water and methanol, soluble in ethanol, and practically insoluble in most organic solvents. Methyl aminolevulinate hydrochloride a weak acid; pKa = 8.1.

Clinical Trials

A. Actinic Ceratosis

Two pivotal multicenter, double-blind, randomized, vehicle-controlled, parallel group Phase III studies (PC T404/05 and PC T405/05) involving 106 patients with 781 actinic keratosis lesions (with a median of 7 lesions per patient) treated with Metvix-PDT were performed, in which the efficacy and safety of Metvix-PDT using the Aktilite CL128 lamp were studied.

Before administration of Metvix cream or vehicle cream, the lesion was prepared to facilitate application of cream and access of light to all parts of the lesion. Scales and crusts were removed with a small dermal curette and the surface of the lesion was gently scraped in order to roughen the surface.

For all the lesions, a thick (approximately 1 mm) layer of study cream was applied directly to the lesion and on 5 mm of surrounding tissue, either with a spatula or by pressing the dressing down over the cream. The amount of cream that was used depended on the size of the lesion. An occlusive dressing was used to cover the area of study cream application. The dressing edges were smoothed down to ensure that the dressing was fixed. When the cream had been in place for 3 hours, the dressing was removed and the study cream was gently wiped off.

The treated skin area was illuminated with a 630 nm red light at the recommended dose of 37 J/cm2 (Aktilite CL128). A second treatment session was performed 7 days later.

1. Placebo-Controlled Studies

Study Demographics and Trial Design

Studies PC T404/05 and PC T405/05 were placebo-controlled, double-blind, randomized, parallel-group Phase III studies designed to assess the safety and effectiveness of Metvix-PDT for the treatment of actinic keratosis. A total of 211 randomized subjects with a total of 1555 non-hyperkeratotic actinic keratoses were studied. All patients in both studies were Caucasians. Gender, age, and skin type were similar in the two studies and were well balanced in the treatment groups within each study. Their other demographic characteristics are found in Table 1-1.

The subject complete response rate was assessed 3 months after the last treatment. Lesion clinical complete response was defined as complete disappearance of a lesion upon visual inspection and palpation. If all treated lesions within a subject were in clinical complete response 3 months after treatment, the subject was assessed as a complete responder.

Table 1-1: Patient Demographics in Placebo-Controlled Studies in Actinic Keratosis
Study PC T404/05 (Study 1) Study PC T405/05 (Study 2) Overall
Metvix
–PDT
n = 49
Vehicle
–PDT
n = 47
Total
–PDT
n = 96
Metvix
–PDT
n = 57
Vehicle
–PDT
n = 58
Total
–PDT
n = 115
Metvix
–PDT
n = 106
Vehicle
–PDT
n = 105
Total
–PDT
n = 211
Gender n (%)
Male 42 (86) 37 (79) 79 (82) 46 (81) 45 (78) 91 (79) 88 (83) 82 (78) 170 (81)
Female 7 (14) 10 (21) 17 (18) 11 (19) 13 (22) 24 (21) 18 (17) 23 (22) 41 (19)
Age (y)
Mean
(SD)
66.1
(10.2)
66.7
(9.2)
66.4
(9.7)
69.5
(9.0)
67.0
(10.4)
68.2
(9.8)
67.9
(9.7)
66.8
(9.8)
67.4
(9.7)
Range 43 – 86 48 – 89 43 – 89 47 – 88 41 – 90 41 – 90 43 – 88 41 – 90 41 – 90
Number (%) of patients aged ≤65 and ≥65 years
≤65 21(43) 22(47) 43(45) 13(23) 28(48) 41(36) 34(32) 50(48) 84(40)
≥65 28(57) 25(53) 53(55) 44(77) 30(52) 74(64) 72(68) 55(52) 127(60)
Number (%) of patients with each skin type
I 12 (24) 10 (21) 22 (23) 10 (18) 12 (21) 22 (19) 22 (21) 22 (21) 44 (21)
II 22 (45) 26 (55) 48 (50) 28 (49) 23 (40) 51 (44) 50 (47) 49 (47) 99 (47)
III 12 (24) 10 (21) 22 (23) 13 (23) 18 (31) 31 (27) 25 (24) 28 (27) 53 (25)
IV 3 (6) 1 (2) 4 (4) 6 (11) 5 (9) 11 (10) 9 (8) 6 (6) 15 (7)

Study Results

Table 1-2 shows patient complete response data. In all studies, Metvix-PDT was clearly superior to Vehicle-PDT in regards to patient complete response (p<0.0001).

Table 1-2: Patients with Complete Response – Placebo-Controlled Studies
Study 1 Study 2
Metvix-PDT
n = 49
Vehicle-PDT
n = 47
Metvix-PDT
n = 57
Vehicle-PDT
n = 58<
Subjects with Complete Response 29
59.2%
7
14.9%
39
68.4%
4
6.9%

Table 1-3 shows the lesion complete response rates. In all studies, the lesion response rates were higher for Metvix-PDT than for Vehicle-PDT.

Table 1-3: Lesion Complete Response in Placebo-Controlled Studies
Study 1 Study 2
Metvix-PDT
n = 363
Vehicle-PDT
n = 360
Metvix-PDT
n = 418
Vehicle-PDT
n = 414
Lesions with Complete Response 313 (86%) 188 (52%) 348 (83%) 119 (29%)
Grade 1 259 267 182* 161
Face Total 191 201 99 88
CR 167 (87%) 121 (60%) 90 (91%) 33 (38%)
Scalp Total 68 66 76 73
CR 63 (93%) 29 (44%) 66 (87%) 31 (42%)
Grade 2 104 93 236* 253
Face Total 76 68 119 157
CR 65 (86%) 29 (43%) 103 (87%) 35 (22%)
Scalp Total 28 25 115 96
CR 18 (64%) 9 (36%) 89 (77%) 20 (21%)

p<0.0001
* The ITT population of Study 2 included 1 patient in the Metvix-PDT group with 9 lesions on the hands; seven grade 1 lesions (4% of all grade 1 lesions in this group) and two grade 2 lesions (1% of all grade 2 lesions). These lesions are included in the overall number of grade 1 and 2 lesions.
CR = complete response

There was no difference between response rates to Metvix-PDT for Grade 1 lesions on the face and scalp (CR rates of 89% and 90% respectively). For Grade 2 lesions, the corresponding CR rates to Metvix-PDT were 86% and 75% respectively.

2. Active-Controlled Studies

Although active-controlled studies were performed, they were primarily designed to collect safety data. Thus, no efficacy data is presented for active-controlled studies.

B. Superficial Basal Cell Carcinoma

Study Demographics and Trial Design

One pivotal Phase III study involving patients with primary superficial basal cell carcinoma (BCC) outside the facial H-zone was performed (Study 29040). In this study, response rates in 100 patients treated with Metvix-PDT in combination with the Aktilite CL128 lamp were compared with those in 96 patients treated with excision surgery.

A total of 196 subjects were enrolled in the 27 sites of whom 66 (33.7%) were female and 130 (66.3%) were male. The mean age was 63.8 years (range 31 to 92 years). All subjects were Caucasian. Of the 196 subjects comprising the Intent to Treat (ITT) and safety populations, 100 were randomized to Metvix-PDT and 96 to excision surgery. There were no notable differences between the treatment groups with respect to demographic characteristics (see Table 1-4). Twenty three (11.7%) subjects discontinued the study and a further 14 (7.1%) subjects were excluded from the Per Protocol (PP) analysis. The PP population comprised 96 subjects randomized to Metvix-PDT and 86 subjects randomized to excision surgery.

Table 1-4: Patient Demographic Data for Superficial Basal Cell Carcinoma Study (ITT)
Gender Metvix Surgery TOTAL
N 100 (100%) 96 (100%) 196 (100%)
Male 64 (64.0%) 66 (68.8%) 130 (66.3%)
Female 36 (36.0%) 30 (31.3%) 66 (33.7%)
Age (in Years) N 100 96 196
Mean ± STD 64.5±12.7 63.1±13.9 63.8±13.3
Median 68.5 66.5 67
(Min, Max) (33,85) (31,92) (31,92)
Race N 100 (100%) 96 (100%) 196 (100%)
Caucasian 100 (100%) 96 (100%) 196 (100%)
Lesion Diameter (mm) N 100 94
Mean ± STD 12.5 ± 3.7 12.6 ± 3.7
Number of Lesions per Patient N 100 96
Median 1.0 1.0
Lesion Distribution 01 79 (79%) 77 (80.2%)
02 11 (11%) 8 (8.3%)
03 7 (7%) 7 (7.3%)
04 2 (2%) 2 (2.1%)
05 1 (1%) 2 (2.1%)

N = Number of subjects evaluable
sd = standard deviation

The primary efficacy variable was the percentage reduction in lesion count per subject 3 months after last treatment. The lesion response was defined as Complete Response (CR; complete clearance of lesion) or Non Complete Response (Non CR; non complete clearance of lesion).

The secondary efficacy variables comprised:

  • Cosmetic outcome assessed by the investigator 3, 6 and 12 months after last treatment.
  • Percentage reduction in lesion count per subject 6 and 12 months after last treatment.

Lesion preparation, Metvix cream application, and illumination procedures were similar to those for the actinic keratosis trials described in the monograph and performed in a standardized manner in all three studies. Assessed efficacy parameters were also similar to those for the actinic keratosis trials.

Study Results

Three months after treatment, the reduction in lesion count per subject was more than 90% in the PP population of the Metvix-PDT and surgery treatment groups with rates of 92% and 99% respectively. The results for the ITT population with last observation carried forward are almost identical for the two treatment groups (87.4% and 89.4% respectively). The key results are shown in Table 1-5.

Table 1-5: Reduction in Lesion Count per subject of Metvix-PDT compared with Surgery 3 months after last treatment
Population Percentage Reduction in Lesion Count
Metvix-PDT Surgery 95% CIs
PP Ls mean ± Std err
Mean ± sd
n=96
92.2 ± 1.8
94.5 ± 21.1
n=86
99.2 ± 1.9
99.4 ± 5.4
[–12.1;–1.9]
ITT-LOCF Ls mean ± Std err
Mean ± sd
n=100
87.4 ± 3.1
90.8 ± 27.8
n=96
89.4 ± 3.1
90.1 ± 29.6
[–;10.6;6.6]

PP – per protocol
ITT – intent to treat
LOCF – last observation carried forward
CI – confidence intervals
LS – least square
Std err – standard error
sd – standard deviation

With regard to secondary outcomes, the efficacy of surgery was superior to that of Metvix-PDT from Month 6 after the last treatment onwards. For the ITT-LOCF population, the average reduction in lesion count by subject was 84% in the Metvix-PDT versus 92% in the surgery group, 6 months after the last treatment (p=0.043) and 79% versus 92%, 12 months after the last treatment (p=0.004). For lesions in CR at 3 months, 91% remained in CR at 12 months versus 100% after surgery.

Cosmetic outcome was assessed by the investigator for each lesion that had responded completely with regard to occurrence of the following signs or symptoms: scarring, atrophy, induration, redness or change in pigmentation. Three and 6 months after the last treatment, cosmetic outcome in Metvix-PDT group was superior to that of the surgery group (p<0.001). Please see Table 1-6 for details. Twelve months after last treatment, the investigator assessed cosmetic outcome was superior for the Metvix-PDT group compared to that of the surgery group (p<0.001), i.e., 92.8% of the subjects were considered success in Metvix-PDT group compared with 51.2% of the subjects in surgery group. Twelve months after the last treatment, 64.7% of lesions had an excellent cosmetic outcome with Metvix-PDT versus 18.8% with surgery. No poor cosmetic outcomes were observed in Metvix– PDT group whereas 5 (4.8%) were rated as poor for the surgery group.

Table 1-6: Cosmetic outcome assessed by investigator 3, 6, and 12 months after the last treatment.
Metvix-PDT Surgery p–value (1)
Month–3 After (observed cases) N
Success
Failure
92 (100.0%)
78 (84.8%)
14 (15.2%)
87 (100.0%)
44 (50.6%)
43 (49.4%)
<0.001

Month–6 After (observed cases) N
Success
Failure
88 (100.0%)
83 (94.3%)
5 (5.7%)
87 (100.0%)
45 (51.7%)
42 (48.3%)
<0.001

Month 12 After (observed cases) N
Success
Failure
83 (100.0%)
77 (92.8%)
6 (7.2%)
86 (100.0%)
44 (51.2%)
44 (51.2%)
<0.001

(1) p-values were obtained from CMH test stratified by pseudo-centre using Ridit score
Success = excellent or good cosmetic outcome
Failure= fair or poor cosmetic outcome

Detailed Pharmacology

Non Clinical Pharmacodynamics

The mode of action of methyl aminolevulinate has been shown in pharmacodynamic studies conducted in tumour cell lines in vitro and in the nude mouse normal skin model in vivo as well as in the scientific literature. After topical application of methyl aminolevulinate, porphyrins accumulate intracellularly in the treated skin lesions. The intracellular porphyrins (including protoporphyrin IX) are photoactive, fluorescing compounds and, upon light activation in the presence of oxygen, singlet oxygen is formed that causes damage to cellular compartments, in particular the mitochondria. This photochemical reaction results in phototoxicity in the light-exposed target cells.

Non Clinical Pharmacokinetics

The dermal penetration of methyl aminolevulinate through skin was investigated in vitro in skin excised from rats and humans. Use of radiolabelled methyl aminolevulinate in topical application in rats for 48 hours resulted in 13.1% and 6.4% systemic absorption through abraded and non-abraded skin respectively. The fraction remaining at the skin application site of rats was quantified to be 6.3 (abraded) and 8.4% (non-abraded) after 24 hours exposure. In contrast, in vitro dermal absorption of radiolabelled methyl aminolevulinate applied to human cadaver skin in a dermal penetration cell (Franz cell) showed that after 24 hours, the mean cumulative absorption through human skin was only 0.26% of the administered dosed. A skin depot containing 4.9% of the dose was formed. No corresponding studies in compromised human skin (damage similar to actinic keratosis, sBCC, roughened surfaces or without stratum corneum) were performed

Clinical Pharmacology

The pharmacokinetics of methyl aminolevulinate cream after topical application in humans in vivo was investigated using the natural fluorescence of photoactive porphyrins (PAPs). The penetration and accumulation of methyl aminolevulinate and PAPs in lesions and normal skin of patients with actinic keratosis (AK) and basal cell carcinoma (BCC) were investigated in two clinical studies. In one study, fluorescence microscopy of lesion biopsies was performed and in the other study, surface fluorescence of lesions and treated normal skin was measured.

Absorption in most lesions achieved a plateau within a few hours. The depth and extent of accumulation of PAPs was greatest with the highest concentration tested (168 mg/g). Increasing the duration of application beyond 10 to 12 hours made little difference to the depth of penetration of fluorescence in the lesion, but increases fluorescence in adjacent normal skin. There was clear evidence of selective localization in lesions relative to surrounding normal skin. Accumulated PAPs appear to be retained in the lesions for many hours after cream application, but subsequent illumination with non-coherent light of 570-670 nm wavelength and a total light dose of 75 J/cm2 resulted in complete photobleaching with levels of porphyrins returning to pre-treatment levels. Illumination with red light with a narrow spectrum at 630 nm and a total light dose of 37 J/cm2 reduced the fluorescence of skin lesions near pre-treatment levels immediately after illumination, but it did not result in complete photobleaching. Thereafter, an increase in fluorescence 2 hours following the illumination was observed. Complete photobleaching was observed 24 hours following the illumination.

The systemic absorption of methyl aminolevulinate in humans has not been properly assessed. No specific tests were performed to assess the urine excretion of methyl aminolevulinate and its derived compounds.

Microbiology

Not Applicable.

Toxicology

A. Special Tolerance Studies in Humans

A cumulative irritancy and sensitization study of Metvix cream was performed in 25 healthy subjects. Signs of mild to moderate skin irritancy were seen in 12 subjects after 4 days of continuous exposure. Challenge applications at previously untested sites following a two-week induction period, resulted in 5 subjects with contact sensitization.

A second cumulative irritancy and sensitization (allergenicity) study of Metvix cream with a cross-sensitization challenge with aminolevulinic acid (ALA) was performed in 156 healthy subjects. Metvix cream was applied 3 times each week for 3 weeks (total of 9 applications), to separate sites on the back of healthy volunteers. After each application, the area was covered by an aluminum Finn Chamber. After the 3–week continuous treatment period and a 2–week interval without further applications, subjects were challenged with Metvix cream, Metvix vehicle, ALA, and ALA–vehicle creams for 48 hours. Assessment of skin reactions was performed 48, 72, and 96 h after start of the challenge cream application. Only 98 of the 156 subjects tested entered the challenge phase because of a high incidence of local irritancy evident as erythema. Of the 58 subjects who were challenged with Metvix cream, 30 (52%) showed contact sensitization. Of the 98 subjects who were challenged with ALA, only 2 (2%) showed equivocal reactions, the remaining subjects having negative responses.

The potential for sensitization was also assessed by patch testing a total of 21 patients with actinic keratoses previously treated with Metvix–PDT on at least 4 previous occasions. Metvix cream 168 mg/g and vehicle cream were applied to different sites on the lower back for 48 hours. Three of the 21 patients (14%) showed contact sensitization associated with erythema scores ≥ 4 (strong erythema spreading outside the patch) and edema, vesiculation, papules and glazing.

These artificially intense conditions are not representative of clinical exposure and to date there have been no cases of contact sensitization in clinical trials and only a few cases in post-marketing surveillance (see Adverse Reactions).

B. Animal Toxicity Studies

Single-Dose Toxicity

Single dose toxicity studies with rats and mice have been performed using two alternative administration routes (Table 2–1). No particular toxicity was observed after oral administration of 2000 mg/kg. With intravenous administration, it was established that the acute minimum lethal dose level of methyl aminolevulinate in the mouse and in the rat were at approximately 925 mg/kg and 1430 – 1500 mg/kg, respectively.

Table 2-1: Single-dose toxicity studies
Species Route of Administration Dosage Form (Vehicle) Doses (mg/kg) No. of animals dosed and Gender
Mouse Oral gavage Cream (Purified Water) 2000 1M, 1F (preliminary)
5M, 5F (main study)
Rat Oral gavage Cream (Purified Water) 2000 2F (preliminary)
5M, 5F (main study)
Mouse IV Cream (Physiological saline) 585
700
840
925
1000
2000
2M
2M
2M
5M
1M
1M, 1F
Rat IV Cream (Physiological saline) 1000
1200
1430
1500(main study)
2000
1M
2M
2M
5M
1M, 1F

Multi-Dose Toxicity

Multi-dose toxicity studies performed in the rat are shown in Table 2–2. The No Observable Effect Level (NOEL) was >250 mg/kg in the 7–day study and 200 mg/kg in the 14–day study.

Table 2-2: Multi-dose toxicity studies
Species Route of Administration Dosage Form (Vehicle) Doses (mg/kg) No. of animals dosed and Gender
Rat IV; Daily for 7 consecutive days Cream (Physiological saline) 250
350
3M, 3F
3M, 3F
Rat IV; Daily for 14 consecutive days Cream (Physiological saline) 50
200
800/600*
10M, 10F
10M, 10F
10M, 10F

* Dose level reduced from 800 to 600 mg/kg/day, from Day 3 onwards, following detection of marked clinical signs of toxicity and death of one male in this group on Day 2.

There were no deaths in the 7–day study. Clinical signs were limited to red/brown staining of the nose and mouth. Clinical pathology revealed reduced blood cell counts, haemoglobin, PCV, and increased lymphocyte and WBC counts among males. Bilirubin levels were elevated in both males and females. No notable macroscopic abnormalities were observed.

In the 14–day study, one male rat died following two doses of 800 mg/kg. Clinical signs in the high–dose group, immediately after dosing, included ataxias, salivation, and noisy respiration. Also observed were increased bilirubin, alanine transferase, and reduced alkaline phosphatase. Dose–related increase in liver weight was manifested in both sexes. The liver is clearly a target organ for toxicity. The observed cholangitis/pericholangitis indicates secretion into the bile duct of the compound or its metabolites.

Genotoxicity

Methyl aminolevulinate had no genotoxic effects in the Ames assay, with and without metabolic activation. Methyl aminolevulinate did not induce chromosomal aberrations in Chinese hamster ovary cells, in the presence or absence of light. Methyl aminolevulinate was also negative in the in vivo micronucleus assay in the rat.

There was evidence of cytotoxicity in the observed trend toward dose–related reduction in cell number. In addition, phototoxic effects were observed at higher light doses. The role of photoactivation in the micronucleus test could not be investigated due to inaccessibility of the rat femur to photoactivating light. In the in vivo micronucleus study, there were no clinical signs at 250 mg/kg/day; however, the following signs emerged at the 500 and 1000 mg/kg/day doses: irregular breathing, pilo–erection, and unsteady gait. At the 1000 mg/kg/day dose, prostration, convulsion, protruding eyes, salivation, eye secretion, and hunched posture were also noted.

Table 2-3: Genotoxicity studies
Type of Study Method of Administration; Dosing Regimen Dosage Form (Vehicle) Dose
Ames Test in vitro; single–dose Cream (Purified Water) In µg/plate: 8 to 5000
Ames Test in vitro with light activation; single–dose Cream (Purified Water) In µg/plate: 5 to 5000
Chromosome aberration using CHO cells in vitro with light activation; single–dose Cream (Purified Water) In µg/plate: 24.45 to 1816
Introducion of micronuclei IV; Daily for 2 consecutive days Cream (Purified Water) In mg/kg:
250
500
1000

Local Tolerance

In the local tolerance studies shown in Table 2-4, there was no indication of systemic toxicity after single or repeated dermal application of methyl aminolevulinate cream. There were no unexpected findings after investigation of the nature of the local lesions both macroscopically and by histopathology after single or repeated dermal treatment. In addition, the skin lesions appeared to heal after repeated treatments.

Pharmacokinetic samplings and analyses have shown no systemic exposure after single treatment, but possible systemic exposure after four successive repeated dermal applications. The eye irritation study results showed that accidental eye exposure does not cause severe adverse effects.

Table 2-4: Local tolerance studies
Species Method of Administration; Dosing Regimen Dose (% P–1202* in cream Exposure Time (h) Photo–activation (j/cm2) No. of animals dosed and Gender
Rat Topical with light activation; Single–dose 20
20
2
20
12
12
12
36
100
200
100
100
11M, 11F
11M, 11F
11M, 11F
11M, 11F
Rat Topical with light activation; Four repeated doses 20
2
10
20
24
24
24
24
0
200
100
100
10M, 10F
10M, 10F
10M, 10F
10M, 10F
Minipig Topical with light activation; Four repeated doses 20 3 75
75
4M, 4F
4M, 4F
Rabbit Ocular; single–dose ~7 mg/kg 2M, 1F
3M
2M, 1F

*P–1202 is methyl 5–aminolevulinate hydrochloride

Skin Sensitization Study

Intradermal injection of 10–60% w/v methyl aminolevulinate cream elicited a positive response, indicative of skin sensitization (delayed contact hypersensitivity) in 13 of the 20 guinea pigs tested.

Carcinogenic or Cocarcinogenic Potential

Long-term studies to evaluate the carcinogenic potential of methyl aminolevulinate have not been performed.

Reproductive Toxicity

A Maximum Topical Human Dose (MTHD) of 2 g of Metvix cream (168 mg/g methyl aminolevulinate) containing 420 mg methyl aminolevulinate hydrochloridecorresponding to 7 mg/kg or 259 mg/m for a 60 kg patient and an estimated maximum systemic uptake of 1% was used for the animal multiple of human systemic exposure calculations presented in this labelling.

Development toxicity studies have been performed in pregnant rats with intravenous doses of methyl aminolevulinate up to 700 mg/kg/day on Days 6 to 16 of gestation. There were no treatment-related effects on fetal body weight, sex ratio, external malformations and variations, and skeletal abnormalities and ossification extent. Only a slight, non-significant increase in early embryonic death was noted in the 700 mg/kg/day group, compared to the control group. The fetal NOAEL (No Adverse Effect Level) was 350 mg/kg/day methyl aminolevulinate in pregnant rats (2100 mg/m2, 811 times the MTHD based on mg/m2 comparisons and an estimated maximum systemic uptake of 1%).

Development toxicity studies have also been performed in pregnant rabbits with intravenous doses of methyl aminolevulinate up to 200 mg/kg/day on Days 6 to 18 of gestation. Slightly lower fetal body weights and increased incidences of fetuses with jugals connected/fused to maxilla, supernumerary ribs, incompletely ossified cranial bones and other ossification irregularities were noted in the high dose (200 mg/kg/day) group, compared to the control group. The fetal NOAEL was 100 mg/kg/day methyl aminolevulinate in pregnant rabbits (1200 mg/m2, 463 times the MTHD based on mg/m2 comparisons and an estimated maximum systemic uptake of 1%).

In the prenatal and postnatal development toxicity study in rats treated with intravenous doses of methyl aminolevulinate up to 500 mg/kg/day from Day 6 of gestation to Day 24 of lactation, there were no treatment-related effects on litter size, pup mortality, pup weights, and post weaning performance of the F1 animals including development and reproductive capacity. Only a slightly longer duration of gestation was noted in the 250 and 500 mg/kg/day groups. The NOAEL was 125 mg/kg/day methyl aminolevulinate hydrochloride (750 mg/m2, 290 times the MTHD based on mg/m2 comparisons and an estimated maximum systemic uptake of 1%).