Hydromorphone

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

documentation insufficient for assessment

Data source

Reference

Reference Type:

publication

Title:

Evaluation of the teratogenic potential of hydromorphone administered via a miniature implantable pump in mice

Author:

Behm MC, Stout-Caputi MV, Mahalik MP and Gautieri RF

Year:

1985

Bibliographic source:

Research Communications in Substance Abuse 6 (3) 165 - 177

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Single injections (5 mg/kg) and continuous infusion of the test material were administered by microosmotic pump to gravid mice and the maternal and foetal effects assessed.

GLP compliance:

no

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Hydromorphone

EC Number:

207-383-5

EC Name:

Hydromorphone

Cas Number:

466-99-9

Molecular formula:

C17H19NO3

IUPAC Name:

(1S,5R,13R,17R)-10-hydroxy-4-methyl-12-oxa-4-azapentacyclo[9.6.1.0^{1,13}.0^{5,17}.0^{7,18}]octadeca-7(18),8,10-trien-14-one

Test animals

Species:

mouse

Strain:

CF-1

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Weight at study initiation: At least 22 g.
- Housing: Females were placed in aggregate cages, each holding 10 animals. Males were placed in individual cages (12.5 x 15 x 10 cm) possessing wire mesh fronts and floors.
- Diet: All animals were maintained on laboratory food ad libitum.
- Water: All animals were maintained on water ad libitum.

Administration / exposure

Route of administration:

subcutaneous

Vehicle:

water

Remarks:

Double distilled

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
The solutions of the test material were prepared every two weeks in concentrations of 31.25, 15.625 and 7.8125 mg/mL, using double distilled water. All solutions were filtered prior to filling the micro-osmotic pumps used to administer the test material.

The gravid mice were randomly assigned to one of 17 experimental categories. The treatments included groups of 3.125, 1.625 and 0.78125 % test material, an untreated control category and saline control treatment groups on Days 7 through 10 of gestation.

Analytical verification of doses or concentrations:

no

Details on mating procedure:

Not reported in reference but citation to Mahalik et. al, 1980 which reports the breeding procedure implemented in the study to achieve timed pregnancies.
Gestation Day 0 is the day of the vaginal plug appearance.

Duration of treatment / exposure:

day 7 through day 10 of gestation

Frequency of treatment:

continuous

Duration of test:

The gravid mice were sacrificed by cervical dislocation on Day 18 (one day prior to term).

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

7.812 other: mgc/mcL

Doses / concentrations 2

Dose / conc.:

15.625 other: mgc/mcL

Doses / concentrations 3

Dose / conc.:

31.25 other: mgc/mcL

No. of animals per sex per dose:

6 pregnant mice per group.

Control animals:

yes, concurrent no treatment

yes, concurrent vehicle

Details on study design:

- Dose selection rationale:
The pilot study evaluating the teratogenic effects of the test material administered subcutaneously utilised a dose of 5 mg/kg. Using the weight of an average mouse (25 g) and considering that the pump delivers 1 µL/h for 7 days, it was determined that a 12.5 % solution of the test material would be required to administer 5 mg/kg of the test material (the dose given subcutaneously) every hour for 7 days. The 12.5 % concentration administered was evaluated for maternal effect in a preliminary study. In addition, two other concentrations (6.25 % and 3.125 %) were tested to provide dose-response representation.
The preliminary investigation showed that both the 12.5 and 6.25 % concentration of the test material administered produced marked maternal toxicity (approximately 50 % fatalities prior to term). The 3.125 % (31.25 mcg/mcL) concentration produced minimal maternal toxicity and was therefore chosen as the high dose. To provide additional dose-response evaluations, lower test material concentrations of 1.5625 % (15.625 mcg/mcL) and 0.78125 % (7.8125 mcg/mcL) were included in the experiment.

Examinations

Maternal examinations:

Behaviour and maternal weight gain.

Ovaries and uterine content:

Incisions along the linea alba as well as two diagonal cuts in the pelvic region formed flaps which were reflected back to expose foetal swellings and resorption sites.

Fetal examinations:

The foetuses were removed, blotted dry and examined for viability (reflex movement to mechanical stimulation), position within the uterine horns, gross abnormalities and gender. The foetuses were weighed to the nearest 0.01 g and alternately distributed to respective solutions for subsequent skeletal and soft tissue analysis.

Statistics:

The data generated was evaluated using Student’s “t” test and the uncorrected Chi^2 test for binomial populations.

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

no effects observed

Description (incidence and severity):

The only abnormal behaviour observed in animals completely recovered from the ether anaesthesia following impantation of the pump, was mild scratching and biting directed dorsally. This was transient and did not result in any deterimental effects to the mother. Post-laparotomy examination of the subcutaneous pocket (implantation site) revealed no infections or septic condition in any of the treated mice.
The only appreciable maternal response observed was straub tail, indicative of CNS stimulation and was obseved only occassionally and almost exclusively in mice receiving 3.125 % test material solution. These minimal maternal effects were anticipated because of the method of dose selection.

Dermal irritation (if dermal study):

not examined

Mortality:

not specified

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

There was a significant decrease observed in maternal weight gain in mice administered the 3.125 % concentration of the test material on Day 10 of gestation when compared to the saline control.

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

not examined

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Other effects:

not examined

Maternal developmental toxicity

Number of abortions:

not specified

Pre- and post-implantation loss:

not specified

Total litter losses by resorption:

not specified

Early or late resorptions:

not specified

Dead fetuses:

not specified

Changes in pregnancy duration:

not specified

Changes in number of pregnant:

not specified

Other effects:

not examined

Effect levels (maternal animals)

Remarks on result:

not measured/tested

Maternal abnormalities

Abnormalities:

not specified

Results (fetuses)

Fetal body weight changes:

effects observed, treatment-related

Description (incidence and severity):

A significant decrease in mean foetal weight occurred in the 3.125 % test material group on Days 7 and 8 of gestation when compared with the saline controls. In addition, significant increases in soft tissue defects (1.5625 % test material on Days 9 and 10; 3.125 % test material on Day 9 and skeletal abnormalities (1.5625 % test material on Day 7; 3.125 % test material on Days 7 and 8) were also observed.

Reduction in number of live offspring:

not specified

Changes in sex ratio:

not specified

Changes in litter size and weights:

not specified

Changes in postnatal survival:

not examined

External malformations:

not specified

Skeletal malformations:

effects observed, treatment-related

Description (incidence and severity):

Skeletal malformations observed at significant levels included: Split supraoccipital, checkerboard and split sternebrae, delayed ossification of the paws, and ectopic ossification sites.
Other skeletal abnormalities observed, but not in statistically significant proportions, included:
Split xiphoid, extra sternebrae, missing parietal, frontal, premaxillary, nasal mandibular, maxillary, sternebrae and xiphoid; delayed ossification of the supraoccipital parietal and nasal processes, split occipital and parietal bones; extra and fused ribs, fractured ribs, fused sternebrae and hypoplasia of the premaxillary, nasal and mandibular processes.

Visceral malformations:

effects observed, treatment-related

Description (incidence and severity):

Cryptorchidism was the only soft tissue anomally observed at significant levels. Other soft tissue defects occurring but not significantly, included intestinal, thoracic, renal and pleural haemorrhage, cleft palate, malformed ventricles and retina, hypoplastic kidney, ectopic tissue formation, hydronephrosis and thoraco-intestinal schists.

Other effects:

not examined

Effect levels (fetuses)

Remarks on result:

not measured/tested

Fetal abnormalities

Abnormalities:

effects observed, treatment-related

Localisation:

other: Skeletal and body weight

Overall developmental toxicity

Developmental effects observed:

yes

Lowest effective dose / conc.:

7.812 other: mgc/mcL

Treatment related:

yes

Relation to maternal toxicity:

not specified

Dose response relationship:

not specified

Relevant for humans:

not specified

Any other information on results incl. tables

Comparison of untreated controls with foetuses born to mothers with implanted pumps and administered saline revealed no significant differences.

Applicant's summary and conclusion

Conclusions:

Subcutaneous injections of the test material to maternal rats resulted in significant skeletal and tissue anomalies to their foetuses.

Executive summary:

The test material was administered as a single injection of 5 mg/kg subcutaneously on only one day of gestation from days 7 through 12.  The test material was found to produce significant numbers of both skeletal and soft tissue anomalies, although its teratogenic potential did not predominate on any particular day of treatment. The foetal malformations observed did, however, parallel the period of ontogenesis for those structures developing during that specific treatment period.