Interactions
Since beta blockers are known to relax the cardiac muscle and to constrict the smooth muscle, beta-adrenergic antagonists, including propranolol, have an additive effect with other drugs which decrease blood pressure, or which decrease cardiac contractility or conductivity. Clinically significant interactions particularly occur with:
Verapamil
Epinephrine (adrenaline)
β2-adrenergic receptor agonists
Salbutamol, levosalbutamol, formoterol, salmeterol, clenbuterol  etc. Clonidine
Ergot alkaloids
Isoprenaline (isoproterenol)
Nonsteroidal anti-inflammatory drugs (NSAIDs)
Quinidine
Cimetidine
Lidocaine
Phenobarbital
Rifampicin
Fluvoxamine (slows down the metabolism of propranolol significantly, leading to increased blood levels of propranolol)

Pharmacology
Pharmacodynamics
Propranolol is classified as a competitive non-cardioselective sympatholytic beta blocker that crosses the blood–brain barrier. It is lipid soluble and also has sodium channel blocking effects. Propranolol is a non-selective β-adrenergic receptor antagonist, or beta blocker; that is, it blocks the action of epinephrine (adrenaline) and norepinephrine (noradrenaline) at both β1- and β2-adrenergic receptors. It has little intrinsic sympathomimetic activity, but has strong membrane stabilizing activity (only at high blood concentrations, e.g. overdose). Propranolol is able to cross the blood–brain barrier and exert effects in the central nervous system in addition to its peripheral activity.In addition to blockade of adrenergic receptors, propranolol has very weak inhibitory effects on the norepinephrine transporter and/or weakly stimulates norepinephrine release (i.e., the concentration of norepinephrine is increased in the synapse). Since propranolol blocks β-adrenoceptors, the increase in synaptic norepinephrine only results in α-adrenoceptor activation, with the α1-adrenoceptor being particularly important for effects observed in animal models. Therefore, it can be looked upon as a weak indirect α1-adrenoceptor agonist in addition to potent β-adrenoceptor antagonist.
This drug is also used off-label in cats and dogs, both by injection and orally. The cross-species nature of IFN-α allow it to work in non-human animals, but the period of usefulness is limited by the production of antibodies against this foreign protein. See also
Interferon
Ropeginterferon alfa-2b

References
External links

Intron-A Summary of Product Characteristics
Nagata S, Taira H, Hall A,  et al. (Mar 1980). "Synthesis in E. coli of a polypeptide with human leukocyte interferon activity". Nature. 284 (5754): 316–20. Bibcode:1980Natur.284..316N. doi:10.1038/284316a0. PMID 6987533. S2CID 4310807.