Follitropin Alfa and Beta

Follitropin alfa (Gonal-F) and follitropin beta (Follistim/Puregon) are real, FDA-approved recombinant versions of FSH, the hormone that drives follicle growth in IVF and ovulation induction — manufactured, rather than purified from urine, for the same underlying biological effect.

Recombinant, not urinary

Follitropin alfa and follitropin beta are recombinant human follicle-stimulating hormone (FSH), produced in CHO cells rather than purified from the urine of postmenopausal women, the way older FSH products (and menotropins, still covered separately on this site) were made. They bind the same FSH receptor on ovarian granulosa cells to recruit and grow follicles during controlled ovarian stimulation for IVF, or to induce ovulation directly. Being a single, well-characterized recombinant molecule rather than a urine-derived extract gives more consistent batch-to-batch potency — the central practical argument for switching to it, not a different mechanism.

The approvals and pivotal trials

Both Gonal-F (follitropin alfa, Serono) and the original Follistim (follitropin beta, Organon) received FDA approval in 1997. Real head-to-head trials against purified urinary FSH followed: Bergh et al. (Hum Reprod 1997, PMID 9402268), a randomized comparison in 235 women, found similar pregnancy rates between recombinant and urinary FSH, with better tolerability for the recombinant product — though OHSS actually occurred more often in the recombinant arm in this particular trial (5.2% vs. 1.7%), a detail worth being precise about rather than assuming recombinant automatically means lower OHSS risk.

The shared OHSS risk

Ovarian hyperstimulation syndrome — excessive, sometimes dangerous ovarian response to stimulation — is a labeled risk across every FSH product, recombinant or urinary, and this site's whole IVF-stimulation-and-trigger cluster exists partly because of it: this is exactly why Cetrorelix and Ganirelix (GnRH antagonists) are used during stimulation, and why the choice of trigger shot (HCG or choriogonadotropin alfa, versus a GnRH-agonist trigger) matters for OHSS-risk patients specifically.

Current status

Both still actively marketed in the US. No FDA-approved US biosimilar for either product was confirmed as of this review — treat any claim of a US generic/biosimilar follitropin with caution until verified directly. No grey-market or wellness-adjacent presence; these are prescription-only, clinic-administered fertility drugs.