Ziconotide, a potent, selective, reversible blocker of neuronal N-type voltage-sensitive calcium channels, is approved in the United States for the management of severe chronic pain in patients for whom intrathecal therapy is warranted, and who are intolerant or refractory to other treatment, such as systemic analgesics, adjunctive therapies, or intrathecal morphine. In the European Union, ziconotide is indicated for the treatment of severe chronic pain in patients who require intrathecal analgesia. Nonclinical investigations of ziconotide included a comprehensive characterization of its toxicology, incorporating acute and subchronic toxicity studies in rats, dogs, and monkeys; reproductive toxicity assessments in rats and rabbits; and mutagenic, carcinogenic evaluations performed in vivo and in vitro. Additional investigations assessed the potential for cardiotoxicity (rats) and immunogenicity (mice, rats, and guinea pigs), and the presence or absence of intraspinal granuloma formation and local cell proliferation and apoptosis (dogs). The resulting nonclinical toxicology profile was predictive of human adverse events reported in clinical trials and consistent with ziconotide's pharmacological activity. Frequently observed nonclinical behavioral effects included tremoring, shaking, ataxia, and hyperreactivity. Occurrences were generally transient and reversible upon cessation of treatment, and intolerable effects occurred at doses more than 45 times the maximum recommended clinical dose. Ziconotide was not associated with target organ toxicity, teratogenicity, or treatment-related gross or histopathological changes; it displayed no mutagenic or carcinogenic potential and no propensity to induce local cell proliferation or apoptosis. Although guinea pigs developed systemic anaphylaxis, antibodies to ziconotide were not detected in mice, rats, or guinea pigs, indicating low immunogenic potential. No evidence of granuloma formation was observed with intrathecal ziconotide treatment. In summary, the results from these nonclinical safety assessments revealed no significant toxicological risk to humans treated with ziconotide as recommended.

Natalizumab had no effects on male fertility, but did result in a reduction in pregnancy rates in females treated with the high dose of 30 mg/kg.

A novel topical tretinoin gel formulation containing a patented TopiCare Delivery Compound, polyolprepolymer-2 (PP-2), was shown to significantly reduce local irritation relative to a marketed tretinoin gel preparation while maintaining clinical efficacy in the treatment of acne. Several in vitro percutaneous absorption studies were conducted with 0.025% tretinoin as a model compound to determine the possible mechanism of action of PP-2 on drug delivery into and through human cadaver skin. Results of these studies have repeatedly shown that a new topical gel formulation containing PP-2 significantly reduces tretinoin penetration while potentially enhancing epidermal deposition compared with a commercial topical gel preparation at the same tretinoin concentration. These studies further support a mechanism of action whereby PP-2 serves as a retentate for drug delivery by formation of a liquid reservoir of polymer and solubilized drug on the skin surface and in the upper layers of the skin, thereby modifying delivery of tretinoin into and through skin. This reservoir of drug and polymer was established within 15 min after topical application, and tretinoin was shown to be highly associated with PP-2. These in vitro findings provide a model by which a new tretinoin gel formulation containing PP-2 reduces irritation relative to a commercial tretinoin gel while maintaining clinical efficacy in the treatment of acne vulgaris.